LM1575, LM2575-N, LM2575HV
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SNVS106E MAY 1999REVISED APRIL 2013
LM1575/LM2575/LM2575HV SIMPLE SWITCHER
®
1A Step-Down Voltage Regulator
Check for Samples: LM1575,LM2575-N,LM2575HV
1FEATURES DESCRIPTION
The LM2575 series of regulators are monolithic
23 3.3V, 5V, 12V, 15V, and Adjustable Output integrated circuits that provide all the active functions
Versions for a step-down (buck) switching regulator, capable of
Adjustable Version Output Voltage Range, driving a 1A load with excellent line and load
1.23V to 37V (57V for HV Version) ±4% regulation. These devices are available in fixed output
voltages of 3.3V, 5V, 12V, 15V, and an adjustable
Max Over output version.
Line and Load Conditions Requiring a minimum number of external
Specified 1A Output Current components, these regulators are simple to use and
Wide Input Voltage Range, 40V up to 60V for include internal frequency compensation and a fixed-
HV Version frequency oscillator.
Requires Only 4 External Components The LM2575 series offers a high-efficiency
52 kHz Fixed Frequency Internal Oscillator replacement for popular three-terminal linear
TTL Shutdown Capability, Low Power Standby regulators. It substantially reduces the size of the
Mode heat sink, and in many cases no heat sink is
required.
High Efficiency A standard series of inductors optimized for use with
Uses Readily Available Standard Inductors the LM2575 are available from several different
Thermal Shutdown and Current Limit manufacturers. This feature greatly simplifies the
Protection design of switch-mode power supplies.
P+Product Enhancement Tested Other features include a specified ±4% tolerance on
output voltage within specified input voltages and
APPLICATIONS output load conditions, and ±10% on the oscillator
Simple High-Efficiency Step-Down (Buck) frequency. External shutdown is included, featuring
Regulator 50 μA (typical) standby current. The output switch
includes cycle-by-cycle current limiting, as well as
Efficient Pre-Regulator for Linear Regulators thermal shutdown for full protection under fault
On-Card Switching Regulators conditions.
Positive to Negative Converter (Buck-Boost)
Typical Application
(Fixed Output Voltage Versions)
Pin numbers are for the TO-220 package.
1Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2SIMPLE SWITCHER is a registered trademark of Texas Instruments.
3All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Copyright © 1999–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
LM1575, LM2575-N, LM2575HV
SNVS106E MAY 1999REVISED APRIL 2013
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Block Diagram and Typical Application
3.3V, R2 = 1.7k
5V, R2 = 3.1k
12V, R2 = 8.84k
15V, R2 = 11.3k
For ADJ. Version
R1 = Open, R2 = 0Ω
Pin numbers are for the TO-220 package.
Figure 1.
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Connection Diagrams
(XX indicates output voltage option.)
Top View Top View Side View
Figure 2. Straight Leads Figure 3. Bent, Staggered Leads Figure 4. LM2575T-XX Flow LB03
or
5-Lead TO-220 Package 5-Lead TO-220 Package LM2575HVT-XX Flow LB03
LM2575T-XX or LM2575HVT-XX See Package Number NDH0005D See Package Number NDH0005D
See Package Number KC0005A
Top View Top View
*No Internal Connection
*No Internal Connection
Figure 5. 16-Lead CDIP and PDIP Packages Figure 6. 24-Lead Surface Mount SOIC Package
LM2575N-XX or LM2575HVN-XX LM2575M-XX or LM2575HVM-XX
LM1575J-XX-QML See Package Number DW0024B
See Package Numbers NFE0016A and NBG
Top View
Figure 7. DDPAK/TO-263 Package
5-Lead Surface-Mount Package
See Package Number KTT0005B
Side View
Figure 8. LM2575S-XX or LM2575HVS-XX
See Package Number KTT0005B
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These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATINGS (1)(2)(3)
Maximum Supply Voltage LM1575/LM2575 45V
LM2575HV 63V
ON /OFF Pin Input Voltage 0.3V V+VIN
Output Voltage to Ground (Steady State) 1V
Power Dissipation Internally Limited
Storage Temperature Range 65°C to +150°C
Maximum Junction Temperature 150°C
Minimum ESD Rating (C = 100 pF, R = 1.5 kΩ) 2 kV
Lead Temperature (Soldering, 10 sec.) 260°C
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for
which the device is intended to be functional, but do not ensure specific performance limits. For specified specifications and test
conditions, see Electrical Characteristics.
(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.
(3) Refer to RETS LM1575J for current revision of military RETS/SMD.
OPERATING RATINGS
Temperature Range LM1575 55°C TJ+150°C
LM2575/LM2575HV 40°C TJ+125°C
Supply Voltage LM1575/LM2575 40V
LM2575HV 60V
ELECTRICAL CHARACTERISTICS LM1575-3.3, LM2575-3.3, LM2575HV-3.3
Specifications with standard type face are for TJ= 25°C, and those with boldface type apply over full Operating
Temperature Range .LM2575-3.3
LM1575-3.3 Units
LM2575HV-3.3
Symbol Parameter Conditions Typ (Limits)
Limit (1) Limit (2)
SYSTEM PARAMETERS Test Circuit Figure 25 and Figure 26(3)
VOUT Output Voltage VIN = 12V, ILOAD = 0.2A 3.3 V
Circuit Figure 25 and Figure 26 3.267 3.234 V(Min)
3.333 3.366 V(Max)
VOUT Output Voltage 4.75V VIN 40V, 0.2A ILOAD 1A 3.3 V
LM1575/LM2575 Circuit Figure 25 and Figure 26 3.200/3.168 3.168/3.135 V(Min)
3.400/3.432 3.432/3.465 V(Max)
VOUT Output Voltage 4.75V VIN 60V, 0.2A ILOAD 1A 3.3 V
LM2575HV Circuit Figure 25 and Figure 26 3.200/3.168 3.168/3.135 V(Min)
3.416/3.450 3.450/3.482 V(Max)
ηEfficiency VIN = 12V, ILOAD = 1A 75 %
(1) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All limits are used to
calculate Average Outgoing Quality Level, and all are 100% production tested.
(2) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits
are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control
(SQC) methods.
(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM1575/LM2575 is used as shown in the test circuit Figure 25 and Figure 26, system performance will be as shown in system
parameters of Electrical Characteristics.
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ELECTRICAL CHARACTERISTICS LM1575-5.0, LM2575-5.0, LM2575HV-5.0
Specifications with standard type face are for TJ= 25°C, and those with boldface type apply over full Operating
Temperature Range.LM2575-5.0
LM1575-5.0 Units
LM2575HV-5.0
Symbol Parameter Conditions Typ (Limits)
Limit (1) Limit (2)
SYSTEM PARAMETERS Test Circuit Figure 25 and Figure 26(3)
VOUT Output Voltage VIN = 12V, ILOAD = 0.2A 5.0 V
Circuit Figure 25 and Figure 26 4.950 4.900 V(Min)
5.050 5.100 V(Max)
VOUT Output Voltage 0.2A ILOAD 1A, 5.0 V
LM1575/LM2575 8V VIN 40V 4.850/4.800 4.800/4.750 V(Min)
Circuit Figure 25 and Figure 26 5.150/5.200 5.200/5.250 V(Max)
VOUT Output Voltage 0.2A ILOAD 1A, 5.0 V
LM2575HV 8V VIN 60V 4.850/4.800 4.800/4.750 V(Min)
Circuit Figure 25 and Figure 26 5.175/5.225 5.225/5.275 V(Max)
ηEfficiency VIN = 12V, ILOAD = 1A 77 %
(1) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All limits are used to
calculate Average Outgoing Quality Level, and all are 100% production tested.
(2) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits
are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control
(SQC) methods.
(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM1575/LM2575 is used as shown in the test circuit Figure 25 and Figure 26, system performance will be as shown in system
parameters of Electrical Characteristics.
ELECTRICAL CHARACTERISTICS LM1575-12, LM2575-12, LM2575HV-12
Specifications with standard type face are for TJ= 25°C, and those with boldface type apply over full Operating
Temperature Range .LM2575-12
LM1575-12 Units
LM2575HV-12
Symbol Parameter Conditions Typ (Limits)
Limit (1) Limit (2)
SYSTEM PARAMETERS Test Circuit Figure 25 and Figure 26 (3)
VOUT Output Voltage VIN = 25V, ILOAD = 0.2A 12 V
Circuit Figure 25 and Figure 26 11.88 11.76 V(Min)
12.12 12.24 V(Max)
VOUT Output Voltage 0.2A ILOAD 1A, 12 V
LM1575/LM2575 15V VIN 40V 11.64/11.52 11.52/11.40 V(Min)
Circuit Figure 25 and Figure 26 12.36/12.48 12.48/12.60 V(Max)
VOUT Output Voltage 0.2A ILOAD 1A, 12 V
LM2575HV 15V VIN 60V 11.64/11.52 11.52/11.40 V(Min)
Circuit Figure 25 and Figure 26 12.42/12.54 12.54/12.66 V(Max)
ηEfficiency VIN = 15V, ILOAD = 1A 88 %
(1) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All limits are used to
calculate Average Outgoing Quality Level, and all are 100% production tested.
(2) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits
are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control
(SQC) methods.
(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM1575/LM2575 is used as shown in the test circuit Figure 25 and Figure 26, system performance will be as shown in system
parameters of Electrical Characteristics.
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ELECTRICAL CHARACTERISTICS LM1575-15, LM2575-15, LM2575HV-15
Specifications with standard type face are for TJ= 25°C, and those with boldface type apply over full Operating
Temperature Range .LM2575-15
LM1575-15 Units
LM2575HV-15
Parameter Conditions Typ (Limits)
Symbol Limit (1) Limit (2)
SYSTEM PARAMETERS Test Circuit Figure 25 and Figure 26(3)
VOUT Output Voltage VIN = 30V, ILOAD = 0.2A 15 V
Circuit Figure 25 and Figure 26 14.85 14.70 V(Min)
15.15 15.30 V(Max)
VOUT Output Voltage 0.2A ILOAD 1A, 15 V
LM1575/LM2575 18V VIN 40V 14.55/14.40 14.40/14.25 V(Min)
Circuit Figure 25 and Figure 26 15.45/15.60 15.60/15.75 V(Max)
VOUT Output Voltage 0.2A ILOAD 1A, 15 V
LM2575HV 18V VIN 60V 14.55/14.40 14.40/14.25 V(Min)
Circuit Figure 25 and Figure 26 15.525/15.675 15.68/15.83 V(Max)
ηEfficiency VIN = 18V, ILOAD = 1A 88 %
(1) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All limits are used to
calculate Average Outgoing Quality Level, and all are 100% production tested.
(2) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits
are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control
(SQC) methods.
(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM1575/LM2575 is used as shown in the test circuit Figure 25 and Figure 26, system performance will be as shown in system
parameters of Electrical Characteristics.
ELECTRICAL CHARACTERISTICS LM1575-ADJ, LM2575-ADJ, LM2575HV-ADJ
Specifications with standard type face are for TJ= 25°C, and those with boldface type apply over full Operating
Temperature Range.LM2575-ADJ
LM1575-ADJ Units
LM2575HV-ADJ
Symbol Parameter Conditions Typ (Limits)
Limit (1) Limit (2)
SYSTEM PARAMETERS Test Circuit Figure 25 and Figure 26(3)
VOUT Feedback Voltage VIN = 12V, ILOAD = 0.2A 1.230 V
VOUT = 5V 1.217 1.217 V(Min)
Circuit Figure 25 and Figure 26 1.243 1.243 V(Max)
VOUT Feedback Voltage 0.2A ILOAD 1A, 1.230 V
LM1575/LM2575 8V VIN 40V 1.205/1.193 1.193/1.180 V(Min)
VOUT = 5V, Circuit Figure 25 and
Figure 26 1.255/1.267 1.267/1.280 V(Max)
VOUT Feedback Voltage 0.2A ILOAD 1A, 1.230 V
LM2575HV 8V VIN 60V 1.205/1.193 1.193/1.180 V(Min)
VOUT = 5V, Circuit Figure 25 and
Figure 26 1.261/1.273 1.273/1.286 V(Max)
ηEfficiency VIN = 12V, ILOAD = 1A, VOUT = 5V 77 %
(1) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All limits are used to
calculate Average Outgoing Quality Level, and all are 100% production tested.
(2) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits
are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control
(SQC) methods.
(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.
When the LM1575/LM2575 is used as shown in the test circuit Figure 25 and Figure 26, system performance will be as shown in system
parameters of Electrical Characteristics.
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ELECTRICAL CHARACTERISTICS ALL OUTPUT VOLTAGE VERSIONS
Specifications with standard type face are for TJ= 25°C, and those with boldface type apply over full Operating
Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version, VIN = 25V for the 12V
version, and VIN = 30V for the 15V version. ILOAD = 200 mA. LM2575-XX
LM1575-XX Units
LM2575HV-XX
Symbol Parameter Conditions Typ (Limits)
Limit (1) Limit (2)
DEVICE PARAMETERS
IbFeedback Bias Current VOUT = 5V (Adjustable Version Only) 50 100/500 100/500 nA
fOOscillator Frequency See (3) 52 kHz
47/43 47/42 kHz(Min)
58/62 58/63 kHz(Max)
VSAT Saturation Voltage IOUT = 1A (4) 0.9 V
1.2/1.4 1.2/1.4 V(Max)
DC Max Duty Cycle (ON) See (5) 98 %
93 93 %(Min)
ICL Current Limit Peak Current (4)(3) 2.2 A
1.7/1.3 1.7/1.3 A(Min)
3.0/3.2 3.0/3.2 A(Max)
ILOutput Leakage Output = 0V 2 2 mA(Max)
Current Output = 1V 7.5 mA
Output = 1V (6)(7) 30 30 mA(Max)
IQQuiescent Current See (6) 5 mA
10/12 10 mA(Max)
ISTBY Standby Quiescent ON /OFF Pin = 5V (OFF) 50 μA
Current 200/500 200 μA(Max)
θJA Thermal Resistance TO-220 Package, Junction to Ambient (8) 65
θJA TO-220 Package, Junction to Ambient (9) 45
θJC TO-220 Package, Junction to Case 2
θJA CDIP Package, Junction to Ambient (10) 85 °C/W
θJA SOIC Package, Junction to Ambient (10) 100
θJA DDPAK/TO-263 Package, Junction to Ambient 37
(11)
(1) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All limits are used to
calculate Average Outgoing Quality Level, and all are 100% production tested.
(2) All limits specified at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits
are 100% production tested. All limits at temperature extremes are specified via correlation using standard Statistical Quality Control
(SQC) methods.
(3) The oscillator frequency reduces to approximately 18 kHz in the event of an output short or an overload which causes the regulated
output voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average power
dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%.
(4) Output (pin 2) sourcing current. No diode, inductor or capacitor connected to output pin.
(5) Feedback (pin 4) removed from output and connected to 0V.
(6) Feedback (pin 4) removed from output and connected to +12V for the Adjustable, 3.3V, and 5V versions, and +25V for the 12V and 15V
versions, to force the output transistor OFF.
(7) VIN = 40V (60V for the high voltage version).
(8) Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with ½ inch leads in a
socket, or on a PC board with minimum copper area.
(9) Junction to ambient thermal resistance (no external heat sink) for the 5 lead TO-220 package mounted vertically, with ½ inch leads
soldered to a PC board containing approximately 4 square inches of copper area surrounding the leads.
(10) Junction to ambient thermal resistance with approximately 1 square inch of pc board copper surrounding the leads. Additional copper
area will lower thermal resistance further. See thermal model in Switchers made Simple software.
(11) If the DDPAK/TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally
connected to the package: Using 0.5 square inches of copper area, θJA is 50°C/W; with 1 square inch of copper area, θJA is 37°C/W;
and with 1.6 or more square inches of copper area, θJA is 32°C/W.
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ELECTRICAL CHARACTERISTICS ALL OUTPUT VOLTAGE VERSIONS (continued)
Specifications with standard type face are for TJ= 25°C, and those with boldface type apply over full Operating
Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version, VIN = 25V for the 12V
version, and VIN = 30V for the 15V version. ILOAD = 200 mA. LM2575-XX
LM1575-XX Units
LM2575HV-XX
Symbol Parameter Conditions Typ (Limits)
Limit (1) Limit (2)
ON /OFF CONTROL Test Circuit Figure 25 and Figure 26
VIH ON /OFF Pin Logic VOUT = 0V 1.4 2.2/2.4 2.2/2.4 V(Min)
Input Level
VIL VOUT = Nominal Output Voltage 1.2 1.0/0.8 1.0/0.8 V(Max)
IIH ON /OFF Pin Input ON /OFF Pin = 5V (OFF) 12 μA
Current 30 30 μA(Max)
IIL ON /OFF Pin = 0V (ON) 0 μA
10 10 μA(Max)
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TYPICAL PERFORMANCE CHARACTERISTICS
(Circuit Figure 25 and Figure 26)
Normalized Output Voltage Line Regulation
Figure 9. Figure 10.
Dropout Voltage Current Limit
Figure 11. Figure 12.
Standby
Quiescent Current Quiescent Current
Figure 13. Figure 14.
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
(Circuit Figure 25 and Figure 26)Switch Saturation
Oscillator Frequency Voltage
Figure 15. Figure 16.
Efficiency Minimum Operating Voltage
Figure 17. Figure 18.
Quiescent Current Feedback Voltage
vs Duty Cycle vs Duty Cycle
Figure 19. Figure 20.
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
(Circuit Figure 25 and Figure 26)Maximum Power Dissipation
Feedback Pin Current (TO-263) (See (1))
Figure 21. Figure 22.
Switching Waveforms Load Transient Response
VOUT = 5V
A: Output Pin Voltage, 10V/div
B: Output Pin Current, 1A/div
C: Inductor Current, 0.5A/div
D: Output Ripple Voltage, 20 mV/div,
AC-Coupled
Horizontal Time Base: 5 μs/divFigure 23. Figure 24.
(1) If the DDPAK/TO-263 package is used, the thermal resistance can be reduced by increasing the PC board copper area thermally
connected to the package: Using 0.5 square inches of copper area, θJA is 50°C/W; with 1 square inch of copper area, θJA is 37°C/W;
and with 1.6 or more square inches of copper area, θJA is 32°C/W.
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TEST CIRCUIT AND LAYOUT GUIDELINES
As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring
inductance generate voltage transients which can cause problems. For minimal inductance and ground loops, the
length of the leads indicated by heavy lines should be kept as short as possible. Single-point grounding (as
indicated) or ground plane construction should be used for best results. When using the Adjustable version,
physically locate the programming resistors near the regulator, to keep the sensitive feedback wiring short.
CIN 100 μF, 75V, Aluminum Electrolytic
COUT 330 μF, 25V, Aluminum Electrolytic
D1 Schottky, 11DQ06
L1 330 μH, PE-52627 (for 5V in, 3.3V out, use 100 μH, PE-92108)
Figure 25. Fixed Output Voltage Versions
where
VREF = 1.23V, R1 between 1k and 5k.
R1 2k, 0.1%
R2 6.12k, 0.1%
Pin numbers are for the TO-220 package.
Figure 26. Adjustable Output Voltage Version
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LM2575 Series Buck Regulator Design Procedure
PROCEDURE (Fixed Output Voltage Versions) EXAMPLE (Fixed Output Voltage Versions)
Given: Given:
VIN(Max) = Maximum Input Voltage VOUT = 5V
VIN(Max) = 20V
VOUT = Regulated Output Voltage (3.3V, 5V, 12V, or 15V) ILOAD(Max) = 0.8A
ILOAD(Max) = Maximum Load Current
1. Inductor Selection (L1) 1. Inductor Selection (L1)
A. Select the correct Inductor value selection guide from Figure 27,A. Use the selection guide shown in Figure 28.
Figure 28,Figure 29 and Figure 30 (Output voltages of 3.3V, 5V, B. From the selection guide, the inductance area intersected by the
12V or 15V respectively). For other output voltages, see the design 20V line and 0.8A line is L330.
procedure of Figure 26 .C. Inductor value required is 330 μH. From the table in Table 2,
B. From the inductor value selection guide, identify the inductance choose AIE 415-0926, Pulse Engineering PE-52627, or RL1952.
region intersected by VIN(Max) and ILOAD(Max), and note the
inductor code for that region.
C. Identify the inductor value from the inductor code, and select an
appropriate inductor from the table shown in Table 2. Part numbers
are listed for three inductor manufacturers. The inductor chosen
must be rated for operation at the LM2575 switching frequency (52
kHz) and for a current rating of 1.15 × ILOAD. For additional inductor
information, see INDUCTOR SELECTION.
2. Output Capacitor Selection (COUT) 2. Output Capacitor Selection (COUT)
A. The value of the output capacitor together with the inductor A. COUT = 100 μF to 470 μF standard aluminum electrolytic.
defines the dominate pole-pair of the switching regulator loop. For B. Capacitor voltage rating = 20V.
stable operation and an acceptable output ripple voltage,
(approximately 1% of the output voltage) a value between 100 μF
and 470 μF is recommended.
B. The capacitor's voltage rating should be at least 1.5 times greater
than the output voltage. For a 5V regulator, a rating of at least 8V is
appropriate, and a 10V or 15V rating is recommended.
Higher voltage electrolytic capacitors generally have lower ESR
numbers, and for this reason it may be necessary to select a
capacitor rated for a higher voltage than would normally be needed.
3. Catch Diode Selection (D1) 3. Catch Diode Selection (D1)
A. The catch-diode current rating must be at least 1.2 times greater A. For this example, a 1A current rating is adequate.
than the maximum load current. Also, if the power supply design B. Use a 30V 1N5818 or SR103 Schottky diode, or any of the
must withstand a continuous output short, the diode should have a suggested fast-recovery diodes shown in Table 1.
current rating equal to the maximum current limit of the LM2575. The
most stressful condition for this diode is an overload or shorted
output condition.
B. The reverse voltage rating of the diode should be at least 1.25
times the maximum input voltage.
4. Input Capacitor (CIN) 4. Input Capacitor (CIN)
An aluminum or tantalum electrolytic bypass capacitor located close A 47 μF, 25V aluminum electrolytic capacitor located near the input
to the regulator is needed for stable operation. and ground pins provides sufficient bypassing.
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Inductor Value Selection Guides
(For Continuous Mode Operation)
Figure 27. LM2575(HV)-3.3 Figure 28. LM2575(HV)-5.0
Figure 29. LM2575(HV)-12 Figure 30. LM2575(HV)-15
Figure 31. LM2575(HV)-ADJ
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PROCEDURE (Adjustable Output Voltage Versions) EXAMPLE (Adjustable Output Voltage Versions)
Given: Given:
VOUT = Regulated Output Voltage VOUT = 10V
VIN(Max) = Maximum Input Voltage VIN(Max) = 25V
ILOAD(Max) = Maximum Load Current ILOAD(Max) = 1A
F = Switching Frequency (Fixed at 52 kHz) F = 52 kHz
1. Programming Output Voltage (Selecting R1 and R2, as shown 1. Programming Output Voltage (Selecting R1 and R2)
in Figure 25 and Figure 26)
Use the following formula to select the appropriate resistor values.
(1) (3)
R1can be between 1k and 5k. (For best temperature coefficient and R2 = 1k (8.13 1) = 7.13k, closest 1% value is 7.15k
stability with time, use 1% metal film resistors)
(2)
2. Inductor Selection (L1) 2. Inductor Selection (L1)
A. Calculate the inductor Volt microsecond constant, A. Calculate E T (V μs)
E T (V μs), from the following formula:
(5)
(4) B. E T = 115 V μs
B. Use the E T value from the previous formula and match it with C. ILOAD(Max) = 1A
the E T number on the vertical axis of the Inductor Value D. Inductance Region = H470
Selection Guide shown in Figure 31.E. Inductor Value = 470 μHChoose from AIE part #430-0634, Pulse
C. On the horizontal axis, select the maximum load current. Engineering part #PE-53118, or Renco part #RL-1961.
D. Identify the inductance region intersected by the E T value and
the maximum load current value, and note the inductor code for that
region.
E. Identify the inductor value from the inductor code, and select an
appropriate inductor from the table shown in Table 2. Part numbers
are listed for three inductor manufacturers. The inductor chosen
must be rated for operation at the LM2575 switching frequency (52
kHz) and for a current rating of 1.15 × ILOAD. For additional inductor
information, see INDUCTOR SELECTION.
3. Output Capacitor Selection (COUT) 3. Output Capacitor Selection (COUT)
A. The value of the output capacitor together with the inductor A.
defines the dominate pole-pair of the switching regulator loop. For
stable operation, the capacitor must satisfy the following (7)
requirement: However, for acceptable output ripple voltage select
COUT 220 μF
(6) COUT = 220 μF electrolytic capacitor
The above formula yields capacitor values between 10 μF and 2000
μF that will satisfy the loop requirements for stable operation. But to
achieve an acceptable output ripple voltage, (approximately 1% of
the output voltage) and transient response, the output capacitor may
need to be several times larger than the above formula yields.
B. The capacitor's voltage rating should be at last 1.5 times greater
than the output voltage. For a 10V regulator, a rating of at least 15V
or more is recommended.
Higher voltage electrolytic capacitors generally have lower ESR
numbers, and for this reason it may be necessary to select a
capacitor rate for a higher voltage than would normally be needed.
(Continued) (Continued)
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PROCEDURE (Adjustable Output Voltage Versions) EXAMPLE (Adjustable Output Voltage Versions)
4. Catch Diode Selection (D1) 4. Catch Diode Selection (D1)
A. The catch-diode current rating must be at least 1.2 times greater A. For this example, a 3A current rating is adequate.
than the maximum load current. Also, if the power supply design B. Use a 40V MBR340 or 31DQ04 Schottky diode, or any of the
must withstand a continuous output short, the diode should have a suggested fast-recovery diodes in Table 1.
current rating equal to the maximum current limit of the LM2575. The
most stressful condition for this diode is an overload or shorted
output. See Table 1.
B. The reverse voltage rating of the diode should be at least 1.25
times the maximum input voltage.
5. Input Capacitor (CIN) 5. Input Capacitor (CIN)
An aluminum or tantalum electrolytic bypass capacitor located close A 100 μF aluminum electrolytic capacitor located near the input and
to the regulator is needed for stable operation. ground pins provides sufficient bypassing.
To further simplify the buck regulator design procedure, TI is making available computer design software to be
used with the Simple Switcher line of switching regulators. Switchers Made Simple (version 3.3) is available on
a (3½) diskette for IBM compatible computers from a TI sales office in your area.
Table 1. Diode Selection Guide
Schottky Fast Recovery
VR1A 3A 1A 3A
20V 1N5817 1N5820
MBR120P MBR320 The following The following
SR102 SR302 diodes are all diodes are all
30V 1N5818 1N5821
MBR130P MBR330 rated to 100V: rated to 100V:
11DQ03 31DQ03 11DF1 31DF1
SR103 SR303 MUR110 MURD310
HER102 HER302
40V 1N5819 IN5822
MBR140P MBR340
11DQ04 31DQ04
SR104 SR304
50V MBR150 MBR350
11DQ05 31DQ05
SR105 SR305
60V MBR160 MBR360
11DQ06 31DQ06
SR106 SR306
Table 2. Inductor Selection by Manufacturer's Part Number
Inductor Code Inductor Value Schott (1) Pulse Eng. (2) Renco (3)
L100 100 μH 67127000 PE-92108 RL2444
L150 150 μH 67127010 PE-53113 RL1954
L220 220 μH 67127020 PE-52626 RL1953
L330 330 μH 67127030 PE-52627 RL1952
L470 470 μH 67127040 PE-53114 RL1951
L680 680 μH 67127050 PE-52629 RL1950
H150 150 μH 67127060 PE-53115 RL2445
H220 220 μH 67127070 PE-53116 RL2446
H330 330 μH 67127080 PE-53117 RL2447
H470 470 μH 67127090 PE-53118 RL1961
H680 680 μH 67127100 PE-53119 RL1960
H1000 1000 μH 67127110 PE-53120 RL1959
(1) Schott Corp., (612) 475-1173, 1000 Parkers Lake Rd., Wayzata, MN 55391.
(2) Pulse Engineering, (619) 674-8100, P.O. Box 12236, San Diego, CA 92112.
(3) Renco Electronics Inc., (516) 586-5566, 60 Jeffryn Blvd. East, Deer Park, NY 11729.
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Table 2. Inductor Selection by Manufacturer's Part Number (continued)
Inductor Code Inductor Value Schott (1) Pulse Eng. (2) Renco (3)
H1500 1500 μH 67127120 PE-53121 RL1958
H2200 2200 μH 67127130 PE-53122 RL2448
APPLICATION HINTS
INPUT CAPACITOR (CIN)
To maintain stability, the regulator input pin must be bypassed with at least a 47 μF electrolytic capacitor. The
capacitor's leads must be kept short, and located near the regulator.
If the operating temperature range includes temperatures below 25°C, the input capacitor value may need to be
larger. With most electrolytic capacitors, the capacitance value decreases and the ESR increases with lower
temperatures and age. Paralleling a ceramic or solid tantalum capacitor will increase the regulator stability at cold
temperatures. For maximum capacitor operating lifetime, the capacitor's RMS ripple current rating should be
greater than
(8)
INDUCTOR SELECTION
All switching regulators have two basic modes of operation: continuous and discontinuous. The difference
between the two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a
period of time in the normal switching cycle. Each mode has distinctively different operating characteristics,
which can affect the regulator performance and requirements.
The LM2575 (or any of the Simple Switcher family) can be used for both continuous and discontinuous modes of
operation.
The inductor value selection guides in Figure 27 through Figure 31 were designed for buck regulator designs of
the continuous inductor current type. When using inductor values shown in the inductor selection guide, the
peak-to-peak inductor ripple current will be approximately 20% to 30% of the maximum DC current. With
relatively heavy load currents, the circuit operates in the continuous mode (inductor current always flowing), but
under light load conditions, the circuit will be forced to the discontinuous mode (inductor current falls to zero for a
period of time). This discontinuous mode of operation is perfectly acceptable. For light loads (less than
approximately 200 mA) it may be desirable to operate the regulator in the discontinuous mode, primarily because
of the lower inductor values required for the discontinuous mode.
The selection guide chooses inductor values suitable for continuous mode operation, but if the inductor value
chosen is prohibitively high, the designer should investigate the possibility of discontinuous operation. The
computer design software Switchers Made Simple will provide all component values for discontinuous (as well
as continuous) mode of operation.
Inductors are available in different styles such as pot core, toriod, E-frame, bobbin core, etc., as well as different
core materials, such as ferrites and powdered iron. The least expensive, the bobbin core type, consists of wire
wrapped on a ferrite rod core. This type of construction makes for an inexpensive inductor, but since the
magnetic flux is not completely contained within the core, it generates more electromagnetic interference (EMI).
This EMI can cause problems in sensitive circuits, or can give incorrect scope readings because of induced
voltages in the scope probe.
The inductors listed in the selection chart include ferrite pot core construction for AIE, powdered iron toroid for
Pulse Engineering, and ferrite bobbin core for Renco.
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An inductor should not be operated beyond its maximum rated current because it may saturate. When an
inductor begins to saturate, the inductance decreases rapidly and the inductor begins to look mainly resistive (the
DC resistance of the winding). This will cause the switch current to rise very rapidly. Different inductor types have
different saturation characteristics, and this should be kept in mind when selecting an inductor.
The inductor manufacturer's data sheets include current and energy limits to avoid inductor saturation.
INDUCTOR RIPPLE CURRENT
When the switcher is operating in the continuous mode, the inductor current waveform ranges from a triangular
to a sawtooth type of waveform (depending on the input voltage). For a given input voltage and output voltage,
the peak-to-peak amplitude of this inductor current waveform remains constant. As the load current rises or falls,
the entire sawtooth current waveform also rises or falls. The average DC value of this waveform is equal to the
DC load current (in the buck regulator configuration).
If the load current drops to a low enough level, the bottom of the sawtooth current waveform will reach zero, and
the switcher will change to a discontinuous mode of operation. This is a perfectly acceptable mode of operation.
Any buck switching regulator (no matter how large the inductor value is) will be forced to run discontinuous if the
load current is light enough.
OUTPUT CAPACITOR
An output capacitor is required to filter the output voltage and is needed for loop stability. The capacitor should
be located near the LM2575 using short pc board traces. Standard aluminum electrolytics are usually adequate,
but low ESR types are recommended for low output ripple voltage and good stability. The ESR of a capacitor
depends on many factors, some which are: the value, the voltage rating, physical size and the type of
construction. In general, low value or low voltage (less than 12V) electrolytic capacitors usually have higher ESR
numbers.
The amount of output ripple voltage is primarily a function of the ESR (Equivalent Series Resistance) of the
output capacitor and the amplitude of the inductor ripple current (ΔIIND). (See INDUCTOR RIPPLE CURRENT).
The lower capacitor values (220 μF–680 μF) will allow typically 50 mV to 150 mV of output ripple voltage, while
larger-value capacitors will reduce the ripple to approximately 20 mV to 50 mV.
Output Ripple Voltage = (ΔIIND) (ESR of COUT) (9)
To further reduce the output ripple voltage, several standard electrolytic capacitors may be paralleled, or a
higher-grade capacitor may be used. Such capacitors are often called “high-frequency,” “low-inductance,” or
“low-ESR.” These will reduce the output ripple to 10 mV or 20 mV. However, when operating in the continuous
mode, reducing the ESR below 0.05Ωcan cause instability in the regulator.
Tantalum capacitors can have a very low ESR, and should be carefully evaluated if it is the only output capacitor.
Because of their good low temperature characteristics, a tantalum can be used in parallel with aluminum
electrolytics, with the tantalum making up 10% or 20% of the total capacitance.
The capacitor's ripple current rating at 52 kHz should be at least 50% higher than the peak-to-peak inductor
ripple current.
CATCH DIODE
Buck regulators require a diode to provide a return path for the inductor current when the switch is off. This diode
should be located close to the LM2575 using short leads and short printed circuit traces.
Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best efficiency,
especially in low output voltage switching regulators (less than 5V). Fast-Recovery, High-Efficiency, or Ultra-Fast
Recovery diodes are also suitable, but some types with an abrupt turn-off characteristic may cause instability and
EMI problems. A fast-recovery diode with soft recovery characteristics is a better choice. Standard 60 Hz diodes
(example: 1N4001 or 1N5400, and so on.) are also not suitable. See Table 1 for Schottky and “soft” fast-
recovery diode selection guide.
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OUTPUT VOLTAGE RIPPLE AND TRANSIENTS
The output voltage of a switching power supply will contain a sawtooth ripple voltage at the switcher frequency,
typically about 1% of the output voltage, and may also contain short voltage spikes at the peaks of the sawtooth
waveform.
The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output
capacitor. (See INDUCTOR SELECTION)
The voltage spikes are present because of the fast switching action of the output switch, and the parasitic
inductance of the output filter capacitor. To minimize these voltage spikes, special low inductance capacitors can
be used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope
probe used to evaluate these transients, all contribute to the amplitude of these spikes.
An additional small LC filter (20 μH & 100 μF) can be added to the output (as shown in Figure 37) to further
reduce the amount of output ripple and transients. A 10 × reduction in output ripple voltage and transients is
possible with this filter.
FEEDBACK CONNECTION
The LM2575 (fixed voltage versions) feedback pin must be wired to the output voltage point of the switching
power supply. When using the adjustable version, physically locate both output voltage programming resistors
near the LM2575 to avoid picking up unwanted noise. Avoid using resistors greater than 100 kΩbecause of the
increased chance of noise pickup.
ON /OFF INPUT
For normal operation, the ON /OFF pin should be grounded or driven with a low-level TTL voltage (typically
below 1.6V). To put the regulator into standby mode, drive this pin with a high-level TTL or CMOS signal. The
ON /OFF pin can be safely pulled up to +VIN without a resistor in series with it. The ON /OFF pin should not be
left open.
GROUNDING
To maintain output voltage stability, the power ground connections must be low-impedance (see Figure 26). For
the TO-3 style package, the case is ground. For the 5-lead TO-220 style package, both the tab and pin 3 are
ground and either connection may be used, as they are both part of the same copper lead frame.
With the CDIP or SOIC packages, all the pins labeled ground, power ground, or signal ground should be
soldered directly to wide printed circuit board copper traces. This assures both low inductance connections and
good thermal properties.
HEAT SINK/THERMAL CONSIDERATIONS
In many cases, no heat sink is required to keep the LM2575 junction temperature within the allowed operating
range. For each application, to determine whether or not a heat sink will be required, the following must be
identified:
1. Maximum ambient temperature (in the application).
2. Maximum regulator power dissipation (in application).
3. Maximum allowed junction temperature (150°C for the LM1575 or 125°C for the LM2575). For a safe,
conservative design, a temperature approximately 15°C cooler than the maximum temperature should be
selected.
4. LM2575 package thermal resistances θJA and θJC.
Total power dissipated by the LM2575 can be estimated as follows:
PD= (VIN) (IQ) + (VO/VIN) (ILOAD) (VSAT)
where
IQ(quiescent current) and VSAT can be found in the Characteristic Curves shown previously,
VIN is the applied minimum input voltage,
VOis the regulated output voltage
and ILOAD is the load current. (10)
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The dynamic losses during turn-on and turn-off are negligible if a Schottky type catch diode is used.
When no heat sink is used, the junction temperature rise can be determined by the following:
ΔTJ= (PD) (θJA) (11)
To arrive at the actual operating junction temperature, add the junction temperature rise to the maximum ambient
temperature.
TJ=ΔTJ+ TA(12)
If the actual operating junction temperature is greater than the selected safe operating junction temperature
determined in step 3, then a heat sink is required.
When using a heat sink, the junction temperature rise can be determined by the following:
ΔTJ= (PD) (θJC +θinterface +θHeat sink) (13)
The operating junction temperature will be:
TJ= TA+ΔTJ(14)
As shown in Equation 14, if the actual operating junction temperature is greater than the selected safe operating
junction temperature, then a larger heat sink is required (one that has a lower thermal resistance).
When using the LM2575 in the plastic CDIP or surface mount SOIC packages, several items about the thermal
properties of the packages should be understood. The majority of the heat is conducted out of the package
through the leads, with a minor portion through the plastic parts of the package. Since the lead frame is solid
copper, heat from the die is readily conducted through the leads to the printed circuit board copper, which is
acting as a heat sink.
For best thermal performance, the ground pins and all the unconnected pins should be soldered to generous
amounts of printed circuit board copper, such as a ground plane. Large areas of copper provide the best transfer
of heat to the surrounding air. Copper on both sides of the board is also helpful in getting the heat away from the
package, even if there is no direct copper contact between the two sides. Thermal resistance numbers as low as
40°C/W for the SOIC package, and 30°C/W for the CDIP package can be realized with a carefully engineered pc
board.
Included on the Switchers Made Simple design software is a more precise (non-linear) thermal model that can
be used to determine junction temperature with different input-output parameters or different component values.
It can also calculate the heat sink thermal resistance required to maintain the regulators junction temperature
below the maximum operating temperature.
ADDITIONAL APPLICATIONS
INVERTING REGULATOR
Figure 32 shows a LM2575-12 in a buck-boost configuration to generate a negative 12V output from a positive
input voltage. This circuit bootstraps the regulator's ground pin to the negative output voltage, then by grounding
the feedback pin, the regulator senses the inverted output voltage and regulates it to 12V.
For an input voltage of 12V or more, the maximum available output current in this configuration is approximately
0.35A. At lighter loads, the minimum input voltage required drops to approximately 4.7V.
The switch currents in this buck-boost configuration are higher than in the standard buck-mode design, thus
lowering the available output current. Also, the start-up input current of the buck-boost converter is higher than
the standard buck-mode regulator, and this may overload an input power source with a current limit less than
1.5A. Using a delayed turn-on or an undervoltage lockout circuit (described in the NEGATIVE BOOST
REGULATOR section) would allow the input voltage to rise to a high enough level before the switcher would be
allowed to turn on.
Because of the structural differences between the buck and the buck-boost regulator topologies, the buck
regulator design procedure section cannot be used to select the inductor or the output capacitor. The
recommended range of inductor values for the buck-boost design is between 68 μH and 220 μH, and the output
capacitor values must be larger than what is normally required for buck designs. Low input voltages or high
output currents require a large value output capacitor (in the thousands of micro Farads).
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The peak inductor current, which is the same as the peak switch current, can be calculated from the following
formula:
where
fosc = 52 kHz. (15)
Under normal continuous inductor current operating conditions, the minimum VIN represents the worst case.
Select an inductor that is rated for the peak current anticipated.
Also, the maximum voltage appearing across the regulator is the absolute sum of the input and output voltage.
For a 12V output, the maximum input voltage for the LM2575 is +28V, or +48V for the LM2575HV.
The Switchers Made Simple (version 3.3) design software can be used to determine the feasibility of regulator
designs using different topologies, different input-output parameters, different components, and so on.
Figure 32. Inverting Buck-Boost Develops 12V
NEGATIVE BOOST REGULATOR
Another variation on the buck-boost topology is the negative boost configuration. The circuit in Figure 33 accepts
an input voltage ranging from 5V to 12V and provides a regulated 12V output. Input voltages greater than
12V will cause the output to rise above 12V, but will not damage the regulator.
Because of the boosting function of this type of regulator, the switch current is relatively high, especially at low
input voltages. Output load current limitations are a result of the maximum current rating of the switch. Also,
boost regulators can not provide current limiting load protection in the event of a shorted load, so some other
means (such as a fuse) may be necessary.
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LM2575-12
2
4
1
3 5
+1N5817
+COUT
1000 PF
Feedback
Output
VIN
CIN
100 PFGND
150 PH
VOUT = -12V
-VIN
-5V to -12V
Low ESR
ON/OFF
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Typical Load Current
200 mA for VIN =5.2V
500 mA for VIN =7V
Pin numbers are for TO-220 package.
Figure 33. Negative Boost
UNDERVOLTAGE LOCKOUT
In some applications it is desirable to keep the regulator off until the input voltage reaches a certain threshold. An
undervoltage lockout circuit which accomplishes this task is shown in Figure 34, while Figure 35 shows the same
circuit applied to a buck-boost configuration. These circuits keep the regulator off until the input voltage reaches
a predetermined level.
VTH VZ1 + 2VBE (Q1) (16)
DELAYED STARTUP
The ON /OFF pin can be used to provide a delayed startup feature as shown in Figure 36. With an input voltage
of 20V and for the part values shown, the circuit provides approximately 10 ms of delay time before the circuit
begins switching. Increasing the RC time constant can provide longer delay times. But excessively large RC time
constants can cause problems with input voltages that are high in 60 Hz or 120 Hz ripple, by coupling the ripple
into the ON /OFF pin.
ADJUSTABLE OUTPUT, LOW-RIPPLE
POWER SUPPLY
A 1A power supply that features an adjustable output voltage is shown in Figure 37. An additional L-C filter that
reduces the output ripple by a factor of 10 or more is included in this circuit.
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Complete circuit not shown.
Pin numbers are for the TO-220 package.
Figure 34. Undervoltage Lockout for Buck Circuit
Complete circuit not shown (see Figure 32).
Pin numbers are for the TO-220 package.
Figure 35. Undervoltage Lockout
for Buck-Boost Circuit
Complete circuit not shown.
Pin numbers are for the TO-220 package.
Figure 36. Delayed Startup
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Pin numbers are for the TO-220 package.
Figure 37. 1.2V to 55V Adjustable 1A Power Supply with Low Output Ripple
Definition of Terms
BUCK REGULATORA switching regulator topology in which a higher voltage is converted to a lower voltage.
Also known as a step-down switching regulator.
BUCK-BOOST REGULATORA switching regulator topology in which a positive voltage is converted to a
negative voltage without a transformer.
DUTY CYCLE (D)Ratio of the output switch's on-time to the oscillator period.
(17)
CATCH DIODE OR CURRENT STEERING DIODEThe diode which provides a return path for the load current
when the LM2575 switch is OFF.
EFFICIENCY (η)The proportion of input power actually delivered to the load.
(18)
CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR)The purely resistive component of a real capacitor's
impedance (see Figure 38). It causes power loss resulting in capacitor heating, which directly affects the
capacitor's operating lifetime. When used as a switching regulator output filter, higher ESR values result in
higher output ripple voltages.
Figure 38. Simple Model of a Real Capacitor
Most standard aluminum electrolytic capacitors in the 100 μF–1000 μF range have 0.5Ωto
0.1ΩESR. Higher-grade capacitors (“low-ESR”, “high-frequency”, or “low-inductance”') in the
100 μF–1000 μF range generally have ESR of less than 0.15Ω.
EQUIVALENT SERIES INDUCTANCE (ESL)The pure inductance component of a capacitor (see Figure 38).
The amount of inductance is determined to a large extent on the capacitor's construction. In a buck
regulator, this unwanted inductance causes voltage spikes to appear on the output.
OUTPUT RIPPLE VOLTAGEThe AC component of the switching regulator's output voltage. It is usually
dominated by the output capacitor's ESR multiplied by the inductor's ripple current (ΔIIND). The peak-to-
peak value of this sawtooth ripple current can be determined by reading INDUCTOR RIPPLE CURRENT.
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CAPACITOR RIPPLE CURRENTRMS value of the maximum allowable alternating current at which a capacitor
can be operated continuously at a specified temperature.
STANDBY QUIESCENT CURRENT (ISTBY)Supply current required by the LM2575 when in the standby mode
(ON /OFF pin is driven to TTL-high voltage, thus turning the output switch OFF).
INDUCTOR RIPPLE CURRENT (ΔIIND)The peak-to-peak value of the inductor current waveform, typically a
sawtooth waveform when the regulator is operating in the continuous mode (vs. discontinuous mode).
CONTINUOUS/DISCONTINUOUS MODE OPERATIONRelates to the inductor current. In the continuous mode,
the inductor current is always flowing and never drops to zero, vs. the discontinuous mode, where the
inductor current drops to zero for a period of time in the normal switching cycle.
INDUCTOR SATURATIONThe condition which exists when an inductor cannot hold any more magnetic flux.
When an inductor saturates, the inductor appears less inductive and the resistive component dominates.
Inductor current is then limited only by the DC resistance of the wire and the available source current.
OPERATING VOLT MICROSECOND CONSTANT (E•Top)The product (in VoIt•μs) of the voltage applied to the
inductor and the time the voltage is applied. This E•Top constant is a measure of the energy handling
capability of an inductor and is dependent upon the type of core, the core area, the number of turns, and
the duty cycle.
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REVISION HISTORY
Changes from Revision D (April 2013) to Revision E Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 25
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PACKAGE OPTION ADDENDUM
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Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM2575HVS-12 NRND DDPAK/
TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2575HVS
-12 P+
LM2575HVS-12/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-12 P+
LM2575HVS-15 NRND DDPAK/
TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2575HVS
-15 P+
LM2575HVS-15/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-15 P+
LM2575HVS-3.3/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-3.3 P+
LM2575HVS-5.0 NRND DDPAK/
TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2575HVS
-5.0 P+
LM2575HVS-5.0/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-5.0 P+
LM2575HVS-ADJ NRND DDPAK/
TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2575HVS
-ADJ P+
LM2575HVS-ADJ/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-ADJ P+
LM2575HVSX-15/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-15 P+
LM2575HVSX-3.3/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-3.3 P+
LM2575HVSX-5.0 NRND DDPAK/
TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2575HVS
-5.0 P+
LM2575HVSX-5.0/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-5.0 P+
LM2575HVSX-ADJ NRND DDPAK/
TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2575HVS
-ADJ P+
LM2575HVSX-ADJ/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575HVS
-ADJ P+
LM2575HVT-12 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575HVT
-12 P+
LM2575HVT-12/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2575HVT
PACKAGE OPTION ADDENDUM
www.ti.com 5-Aug-2020
Addendum-Page 2
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
-12 P+
LM2575HVT-12/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575HVT
-12 P+
LM2575HVT-12/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575HVT
-12 P+
LM2575HVT-15 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575HVT
-15 P+
LM2575HVT-15/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2575HVT
-15 P+
LM2575HVT-15/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575HVT
-15 P+
LM2575HVT-15/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575HVT
-15 P+
LM2575HVT-3.3/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575HVT
-3.3 P+
LM2575HVT-3.3/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575HVT
-3.3 P+
LM2575HVT-5.0 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575HVT
-5.0 P+
LM2575HVT-5.0/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2575HVT
-5.0 P+
LM2575HVT-5.0/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575HVT
-5.0 P+
LM2575HVT-5.0/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575HVT
-5.0 P+
LM2575HVT-ADJ NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575HVT
-ADJ P+
LM2575HVT-ADJ/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2575HVT
-ADJ P+
LM2575HVT-ADJ/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575HVT
-ADJ P+
LM2575HVT-ADJ/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575HVT
-ADJ P+
LM2575M-5.0 NRND SOIC DW 24 30 TBD Call TI Call TI -40 to 125 LM2575M
-5.0 P+
PACKAGE OPTION ADDENDUM
www.ti.com 5-Aug-2020
Addendum-Page 3
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM2575M-5.0/NOPB ACTIVE SOIC DW 24 30 Green (RoHS
& no Sb/Br) SN Level-3-260C-168 HR -40 to 125 LM2575M
-5.0 P+
LM2575M-ADJ/NOPB ACTIVE SOIC DW 24 30 Green (RoHS
& no Sb/Br) SN Level-3-260C-168 HR -40 to 125 LM2575M
-ADJ P+
LM2575MX-5.0/NOPB ACTIVE SOIC DW 24 1000 Green (RoHS
& no Sb/Br) SN Level-3-260C-168 HR -40 to 125 LM2575M
-5.0 P+
LM2575MX-ADJ/NOPB ACTIVE SOIC DW 24 1000 Green (RoHS
& no Sb/Br) SN Level-3-260C-168 HR -40 to 125 LM2575M
-ADJ P+
LM2575S-12/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-12 P+
LM2575S-15/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-15 P+
LM2575S-3.3 NRND DDPAK/
TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2575S
-3.3 P+
LM2575S-3.3/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-3.3 P+
LM2575S-5.0 NRND DDPAK/
TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2575S
-5.0 P+
LM2575S-5.0/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-5.0 P+
LM2575S-ADJ NRND DDPAK/
TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2575S
-ADJ P+
LM2575S-ADJ/NOPB ACTIVE DDPAK/
TO-263 KTT 5 45 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-ADJ P+
LM2575SX-12/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-12 P+
LM2575SX-15/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-15 P+
LM2575SX-3.3/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-3.3 P+
LM2575SX-5.0/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-5.0 P+
LM2575SX-ADJ NRND DDPAK/
TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2575S
-ADJ P+
PACKAGE OPTION ADDENDUM
www.ti.com 5-Aug-2020
Addendum-Page 4
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM2575SX-ADJ/NOPB ACTIVE DDPAK/
TO-263 KTT 5 500 Green (RoHS
& no Sb/Br) SN Level-3-245C-168 HR -40 to 125 LM2575S
-ADJ P+
LM2575T-12 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575T
-12 P+
LM2575T-12/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575T
-12 P+
LM2575T-12/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575T
-12 P+
LM2575T-15 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575T
-15 P+
LM2575T-15/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575T
-15 P+
LM2575T-15/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575T
-15 P+
LM2575T-3.3/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575T
-3.3 P+
LM2575T-3.3/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575T
-3.3 P+
LM2575T-5.0 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575T
-5.0 P+
LM2575T-5.0/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2575T
-5.0 P+
LM2575T-5.0/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575T
-5.0 P+
LM2575T-5.0/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575T
-5.0 P+
LM2575T-ADJ NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2575T
-ADJ P+
LM2575T-ADJ/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2575T
-ADJ P+
LM2575T-ADJ/LF02 ACTIVE TO-220 NEB 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575T
-ADJ P+
LM2575T-ADJ/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM LM2575T
-ADJ P+
PACKAGE OPTION ADDENDUM
www.ti.com 5-Aug-2020
Addendum-Page 5
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
LM2575T-ADJ/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS
& no Sb/Br) SN Level-1-NA-UNLIM -40 to 125 LM2575T
-ADJ P+
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
LM2575HVSX-15/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575HVSX-3.3/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575HVSX-5.0 DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575HVSX-5.0/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575HVSX-ADJ DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575HVSX-ADJ/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575MX-5.0/NOPB SOIC DW 24 1000 330.0 24.4 10.8 15.9 3.2 12.0 24.0 Q1
LM2575MX-ADJ/NOPB SOIC DW 24 1000 330.0 24.4 10.8 15.9 3.2 12.0 24.0 Q1
LM2575SX-12/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575SX-15/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575SX-3.3/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575SX-5.0/NOPB DDPAK/ KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
PACKAGE MATERIALS INFORMATION
www.ti.com 14-Jul-2020
Pack Materials-Page 1
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
TO-263
LM2575SX-ADJ DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
LM2575SX-ADJ/NOPB DDPAK/
TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LM2575HVSX-15/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575HVSX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575HVSX-5.0 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575HVSX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575HVSX-ADJ DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575HVSX-ADJ/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575MX-5.0/NOPB SOIC DW 24 1000 367.0 367.0 45.0
LM2575MX-ADJ/NOPB SOIC DW 24 1000 367.0 367.0 45.0
LM2575SX-12/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575SX-15/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575SX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575SX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
PACKAGE MATERIALS INFORMATION
www.ti.com 14-Jul-2020
Pack Materials-Page 2
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LM2575SX-ADJ DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
LM2575SX-ADJ/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0
PACKAGE MATERIALS INFORMATION
www.ti.com 14-Jul-2020
Pack Materials-Page 3
www.ti.com
PACKAGE OUTLINE
C
B
9.25
7.67
6.86
5.69
3.05
2.54
14.73
12.29
5X 1.02
0.64
4X 1.7
8.89
6.86
12.88
10.08
(6.275)
4.83
4.06 1.40
1.14
3.05
2.03
0.61
0.30
-3.963.71
6.8
2X (R1)
OPTIONAL
16.51
MAX
A
10.67
9.65
(4.25)
4215009/A 01/2017
TO-220 - 16.51 mm max heightKC0005A
TO-220
NOTES:
1. All controlling linear dimensions are in inches. Dimensions in brackets are in millimeters. Any dimension in brackets or parenthesis are for
reference only. Dimensioning and tolerancing per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. Shape may vary per different assembly sites.
0.25 C A B
PIN 1 ID
(OPTIONAL)
15
OPTIONAL
CHAMFER
SCALE 0.850
NOTE 3
15
AAAA
www.ti.com
EXAMPLE BOARD LAYOUT
0.07 MAX
ALL AROUND
0.07 MAX
ALL AROUND (1.45)
(2)
(R0.05) TYP
4X (1.45)
4X (2)
5X ( 1.2) (1.7) TYP
(6.8)
FULL R
TYP
TO-220 - 16.51 mm max heightKC0005A
TO-220
4215009/A 01/2017
LAND PATTERN
NON-SOLDER MASK DEFINED
SCALE:12X
PKG
PKG
METAL
TYP
SOLDER MASK
OPENING, TYP
15
MECHANICAL DATA
NDH0005D
www.ti.com
MECHANICAL DATA
KTT0005B
www.ti.com
BOTTOM SIDE OF PACKAGE
TS5B (Rev D)
MECHANICAL DATA
NEB0005F
www.ti.com
MECHANICAL DATA
NEB0005B
www.ti.com
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