MIC4575BUTR - Micrel - Datasheet.Support

MIC4575

200kHz Simple 1A Buck Regulator

Pentium is a registered trademark of Intel Corporation

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

July 2009 1 M9999-072909

General Description

The MIC4575 is a series of easy to use fixed and

adjustable BiCMOS step-down (buck) switch-mode voltage

regulators. The 200kHz MIC4575 duplicates the pinout

and function of the 52kHz LM2575. The higher switching

frequency may allow up to a 2:1 reduction in output filter

inductor size.

The MIC4575 is available in 3.3V, and 5V fixed output

versions or a 1.23V to 20V adjustable output version. Both

versions are capable of driving a 1A load with excellent

line and load regulation.

The feedback voltage is guaranteed to ±2% tolerance for

adjustable versions, and the output voltage is guaranteed

to ±3% for fixed versions, within specified voltages and

load conditions. The oscillator frequency is guaranteed to

±10%.

In shutdown mode, the regulator draws less than 200µA

standby current. The regulator performs cycle-by-cycle

current limiting and thermal shutdown for protection under

fault conditions.

This series of simple switch-mode regulators requires a

minimum number of external components and can operate

using a standard series of inductors. Frequency comp-

ensation is provided internally.

The MIC4575 is available in TO-220 (T) and TO-263 (U)

packages for the industrial temperature range.

Data sheets and support documentation can be found on

Micrel’s web site at www.micrel.com.

Features

• Fixed 200kHz operation

• 3.3V, 5V, and adjustable output versions

• Voltage over specified line and load conditions:

• Fixed version: ±3% max. output voltage

• Adjustable version: ±2% max. feedback voltage

• Guaranteed 1A switch current

• Wide 4V to 24V input voltage range

• Wide 1.23V to 20V output voltage range

• Requires minimum external components

• < 200µA typical shutdown mode

• 75% efficiency (adjustable version > 75% typical)

• Standard inductors and capacitors are25% of typical

LM2575 values

• Thermal shutdown

• Overcurrent protection

• 100% electrical thermal limit burn-in

Applications

• Simple high-efficiency step-down (buck) regulator

• Efficient pre-regulator for linear regulators

• On-card switching regulators

• Positive-to-negative converter (inverting buck-boost)

• Battery charger

• Negative boost converter

• Step-down 6V to 3.3V for Intel Pentium® and similar

microprocessors

___________________________________________________________________________________________________________

Typical Application

150µF

35V

1N5819

330µF

16V

68µH

GND

MIC4575-5.0_T

SHDN

8V to 24V

5.0V/1A

VIN

Shutdown

Enable

Fixed Regulator Adjustable Regulator

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Ordering Information

Part Number

Standard RoHS Compliant*

Voltage Temperature Range Package

MIC4575-3.3BT MIC4575-3.3WT 3.3V –40° to +85°C 5-Pin TO-220

MIC4575-5.0BT MIC4575-5.0WT 5.0V –40° to +85°C 5-Pin TO-220

MIC4575BT MIC4575WT Adj. –40° to +85°C 5-Pin TO-220

MIC4575-3.3BU MIC4575-3.3WU 3.3V –40° to +85°C 5-Pin TO-263

MIC4575-5.0BU MIC4575-5.0WU 5.0V –40° to +85°C 5-Pin TO-263

MIC4575BU MIC4575WU Adj. –40° to +85°C 5-Pin TO-263

* RoHS compliant with ‘high-melting solder’ exemption.

Pin Configur ation

BAT

5 SHDN

4FB

3 GND

2SW

1 VIN

5-Pin TO-220 (T) 5-Pin TO-263 (U)

Pin Description

Pin Number Pin Name Pin Function

1 IN Supply Voltage (Input): Unregulated +4V to +40V supply voltage.

2 SW

Switch (Output): Emitter of NPN output switch. Connect to external storage

inductor and Shottky diode.

3, TAB GND Ground.

4 FB

Feedback (Input): Output voltage feedback to regulator. Connect to output of

supply for fixed versions. Connect to 1.23V tap of resistive divider for adjustable

versions.

5 SHDN

Shutdown (Input): Logic low enables regulator. Logic high (> 2.4V) shuts down

regulator.

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Absolute Maximum Ratings

Supply Voltage (VIN)(1) ..................................................+40V

Shutdown Voltage (VSHDN)............................. –0.3V to +36V

Output Switch (VSW) .......................................................–1V

Storage Temperature (Ts) ...........................–65°C to 150°C

ESD(2)

Operating Ratings

Supply Voltage (VIN).....................................................+24V

Junction Temperature (TJ) ....................................... +150°C

Package Thermal Resistance

TO-220, TO-263 (θJA) ........................................65°C/W

TO-220, TO-263 (θJC) ..........................................2°C/W

Electrical Characteristics(4)

VIN = 12V; ILOAD = 200mA; TJ = 25°C, bold values indicate –40°C< TJ < +85°C, unless noted.

Parameter Condition Min Typ Max Units

MIC4575 [Adjustable]

Feedback Voltage 1.217 1.230 1.243 V

Feedback Voltage 8V ≤ VIN ≤ 24V, 0.2A ≤ ILOAD ≤ 1A 1.193

1.180

1.230 1.267

1.280

Efficiency ILOAD = 1A, VOUT = 5V 77 %

Feedback Bias Current 50 100

500

MIC4575-3.3

Output Voltage 3.234 3.3 3.366 V

Output Voltage 6V ≤ VIN ≤ 24V, 0.2A ≤ ILOAD ≤ 1A 3.168

3.135

3.3 3.432

3.465

Efficiency ILOAD = 1A 72 %

MIC4575-5.0

Output Voltage 4.900 5.0 5.100 V

Output Voltage 8V ≤ VIN ≤ 24V, 0.2A ≤ ILOAD ≤ 1A 4.800

4.750

5.0 5.200

5.250

Efficiency ILOAD = 1A 77 %

MIC4575 / -3.3 / -5.0

Oscillator Frequency 180 200 220 kHz

Saturation Voltage IOUT = 1A 1 1.3

1.5

Maximum Duty Cycle (On) FB connected to 0V 90 95 %

Current Limit Peak Current, tON ≤ 3µs 1.7

1.3

2.2 3.0

3.2

Output Leakage Current VIN = 24V, FB connected to 0V

Output = 0V

Output = –1V

7.5

Quiescent Current 5 10 mA

Standby Quiescent Current SHDN = 5V (regulator off) 50 200 µA

SHDN Input Logic Level VOUT = 0V (regulator off) 2.2

2.4

1.4 V

VOUT = 3.3 or 5V (regulator on) 1.2 1.0

0.8

SHDN Input Current

SHDN = 5V (regulator off)

SHDN = 0V (regulator on)

–10

0.01

µA

Notes:

1. The MIC4575 is not guaranteed to survive a short circuit to ground for input voltage above 24V.

2. Devices are ESD sensitive. Handling precautions recommended.

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Functional Diagram

Block Diagram with External Components

Fixed Step-Down Regulator

⎛

⎜

⎝

⎛

⎜

⎝

⎛

⎜

⎝

⎛

⎜

⎝

Block Diagram with External Components

Adjustable Step-Down Regulator

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Functional Description

The MIC4575 is a variable duty cycle switch-mode

regulator with an internal power switch. Refer to the

block diagrams.

Supply Voltage

The MIC4575 operates from a +4V to +24V unregulated

input. Highest efficiency operation is from a supply

voltage around +15V.

Enable/Shutdown

The shutdown (SHDN) input is TTL compatible. Ground

the input if unused. A logic-low enables the regulator. A

logic-high shuts down the internal regulator which

reduces the current to typically 50µA.

Feedback

Fixed versions of the regulator have an internal resistive

divider from the feedback (FB) pin. Connect FB directly

to the output line.

Adjustable versions require an external resistive voltage

divider from the output voltage to ground, connected

from the1.23V tap to FB.

Duty Cycle Control

A fixed-gain error amplifier compares the feedback

signal with a 1.23V bandgap voltage reference. The

resulting error amplifier output voltage is compared to a

200kHz sawtooth waveform to produce a voltage

controlled variable duty cycle output.

A higher feedback voltage increases the error amplifier

output voltage. A higher error amplifier voltage

(comparator inverting input) causes the comparator to

detect only the peaks of the sawtooth, reducing the duty

cycle of the comparator output. A lower feedback voltage

increases the duty cycle.

Output Switching

When the internal switch is on, an increasing current

flows from the supply VIN, through external storage

inductor L1, to output capacitor COUT and the load.

Energy is stored in the inductor as the current increases

with time.

When the internal switch is turned off, the collapse of the

magnetic field in L1 forces current to flow through fast

recovery diode D1, charging COUT.

Output Capacitor

External output capacitor COUT provides stabilization and

reduces ripple.

Return Paths

During the on portion of the cycle, the output capacitor

and load currents return to the supply ground. During the

off portion of the cycle, current is being supplied to the

output capacitor and load by storage inductor L1, which

means that D1 is part of the high-current return path.

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Application Information

The applications circuits that follow have been

constructed and tested. Refer to Application Note 15 for

additional information, including efficiency graphs and

manufacturer’s addresses and telephone numbers for

most circuits.

For a mathematical approach to component selection

and circuit design, refer to Application Note 14.

Figure 1. 6V–24V to 3.3V/1A Buck Converter

Through Hole

Figure 2. 8V–24V to 5V/1A Buck Converter

Through Hole

68µF

63V

MBR160

330µF

16V

150µH

GND

MIC4575BT

SHDN

16V to 24V

12V/1A

VIN

13.0k

1.50k

C1 Nichicon

C2 Nichicon

D1 Motorola MBR160

L1 Sumida

Figure 3. 16V–24V to 12V/1A Buck Converter

Through Hole

Note 2: Surface-mount component.

Figure 4. 6V–24V to 3.3V/1A Buck Converter

Low-Profile Surface Mount

Figure 5. 8V–24V to 5V/1A Buck Converter

Low-Profile Surface Mount

Figure 6. 16V–24V to 12V/1A Buck Converter

Low-Profile Surface Mount

Figure 7. 6V–24V to 3.3V/1A Buck Converter

Lower-Cost Surface Mount

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Figure 8. 8V–24V to 5V/1A Buck Converter

Lower-Cost Surface Mount

Figure 9. 16V–24V to 12V/1A Buck Converter

Lower-Cost Surface Mount

Figure 10. 8V–18V to –5V/0.2A Buck-Boost Converter

Through Hole

Figure 11. 5V to –5V/0.3A Buck-Boost Converter

Through Hole

22µF

35V

MBRS130LT3

GND

MIC4575BU

SHDN

VIN

8V to 18V VIN

C1 AVX

C2 AVX

C4 AVX

D1 Motorola MBRS130LT3

T1 Coiltronics

L1 Coilcraft DO1608C-102

68µH L1

1µH

220µF

10V

3.01k

1.00K

3300pF

220µF

10V

VOUT

5V/1A

5mVP-P

Figure 12. Low Output-Noise Regulator (5mV Output Ripple )

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22µF

35V

MBRS130LT3

GND

MIC4575BU

SHDN

VIN

8V to 18V VIN

C1 AVX

C2 AVX

C4 AVX

C5 AVX

D1 Motorola MBRS130LT3

D2 Motorola MBRS130LT3

T1 Coiltronics

68µH

3.01k

1.00K

3300pF C2

220µF

10V

+VOUT

/+IOUT

5V/0.5A

-VOUT

/-IOUT

-5V/0.5A

at VIN 15V

Load Regulation 5%

MBRS130LT3

220µF

10V

220µF

10V

DC +V + 0.5V

V– 0.5V

40% then – I

+I +–I A

40% then – I × (1 – DC)

Figure 13. Split ±5V Supply

Figure 14. Adjustable (0V–12V) Output-Voltage Regulator

150µF

35V

1N5819

GND

MIC4575BT

SHDN

VIN

4V to 15V VIN

D1 Motorola 1N5819

U2 National LM358

68µH VOUT

1V/1A

249

1.00k

330µF

16V R3

LM358

Figure 15. Low Output-Voltage Regulator (1V)

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Figure 16. 1A Battery Charg er (6–8 c ells)

0.01µF

150µF

35V

1N5819

GND

MIC4575-BT

SHDN

VIN

8V to 24V VIN

U1 Micrel MIC4575BT

U2 National LM358

U3 Micrel LM4041CIZ-1.2

C1 Nichicon

C2 Nichicon

D1 Motorola 1N5819

D2 Motorola 1N5819

D3 Motorola 1N4148

L1 Coiltronics

R1 KRL SP-1-A1-0R100J

Q1 Siliconix VN2222LL

DZ1

1N5244

14V

10k

0.1

100

330µF

16V

1N5819

VIN

1.21k

U2B

1/2 LM358

VN2222LL

VR1

10k

LM4041CIZ-1.2

VIN

10k

2-8 Cells

VBATT

IOUT

0.1A to 1A

U2A

1/2LM358

68µH

1000pF

/ 0.9 + 2.5V

1N4148

Figure 17. 0.1A–1A Variable-Current Batter y Charge r

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Figure 18. 1A Battery Charger (2–8 C ells)

Figure 19. Remote-Sensing Regulator

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Figure 20. 6V–18V to Split ±12V/100mA Supply

Figure 21. 1A Battery Charg er

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⎛

⎜

⎝

⎛

⎜

⎝

Figure 22. Improved Adjustable Output-Voltage Regulator (0V–12V)

Figure 23. Switchable Batter y-Pack Charger

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⎛

⎜

⎝

⎛

⎜

⎝

Figure 24. Lithium-Ion Battery Charger with End-of-Charge Flag

⎛

⎜

⎝

⎛

⎜

⎝

Figure 25. Low Output-Noise Regulator (<1mV)

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Package Information

5-Pin TO-220 (T)

5-Pin TO-263 (U)

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July 2009 15 M9999-072909

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com

The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its

use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product

can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant

into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A

Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully

indemnify Micrel for any damages resulting from such use or sale.