LT1790
1
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TYPICAL APPLICATION
DESCRIPTION
Micropower SOT-23
Low Dropout Reference Family
FEATURES
APPLICATIONS
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
The LT
®
1790 is a family of SOT-23 micropower low dropout
series references that combine high accuracy and low drift
with low power dissipation and small package size. These
micropower references use curvature compensation to
obtain a low temperature coeffi cient and trimmed preci-
sion thin-fi lm resistors to achieve high output accuracy. In
addition, each LT1790 is post-package trimmed to greatly
reduce the temperature coeffi cient and increase the output
accuracy. Output accuracy is further assured by excellent
line and load regulation. Special care has been taken to
minimize thermally induced hysteresis.
The LT1790s are ideally suited for battery-operated sys-
tems because of their small size, low supply current and
reduced dropout voltage. These references provide sup-
ply current and power dissipation advantages over shunt
references that must idle the entire load current to operate.
Since the LT1790 can also sink current, it can operate as
a micropower negative voltage reference with the same
performance as a positive reference.
n High Accuracy:
A Grade—0.05% Max
B Grade—0.1% Max
n Low Drift:
A Grade—10ppm/°C Max
B Grade—25ppm/°C Max
n Low Thermal Hysteresis 40ppm (Typical) –40°C to 85°C
n Low Supply Current: 60μA Max
n Sinks and Sources Current
n Low Dropout Voltage
n Guaranteed Operational –40°C to 125°C
n Wide Supply Range to 18V
n Available Output Voltage Options: 1.25V, 2.048V,
2.5V, 3V, 3.3V, 4.096V and 5V
n Low Profi le (1mm) ThinSOT™ Package
n Handheld Instruments
n Negative Voltage References
n Industrial Control Systems
n Data Acquisition Systems
n Battery-Operated Equipment
Typical VOUT Distribution for LT1790-2.5Positive Connection for LT1790-2.5
0.1μF
2.6V ≤ V
IN
≤ 18V
1μF
1, 2
6V
OUT
= 2.5V
4LT1790-2.5
1790 TA01
OUTPUT VOLTAGE (V)
2.498 2.499 2.500 2.501 2.502
NUMBER OF UNITS
30
40
50
1790 TA02
20
10
25
35
45
15
5
0
LT1790B LIMITS
LT1790A LIMITS
167 UNITS
LT1790
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PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS
(Note 1)
ORDER INFORMATION
LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LT1790ACS6-1.25#PBF LT1790ACS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-1.25#PBF LT1790AIS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-1.25#PBF LT1790BCS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-1.25#PBF LT1790BIS6-1.25#TRPBF LTXT 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-2.048#PBF LT1790ACS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-2.048#PBF LT1790AIS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-2.048#PBF LT1790BCS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-2.048#PBF LT1790BIS6-2.048#TRPBF LTXU 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-2.5#PBF LT1790ACS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-2.5#PBF LT1790AIS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-2.5#PBF LT1790BCS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-2.5#PBF LT1790BIS6-2.5#TRPBF LTPZ 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-3#PBF LT1790ACS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-3#PBF LT1790AIS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-3#PBF LT1790BCS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-3#PBF LT1790BIS6-3#TRPBF LTQA 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-3.3#PBF LT1790ACS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-3.3#PBF LT1790AIS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-3.3#PBF LT1790BCS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-3.3#PBF LT1790BIS6-3.3#TRPBF LTXW 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-4.096#PBF LT1790ACS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-4.096#PBF LT1790AIS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-4.096#PBF LT1790BCS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-4.096#PBF LT1790BIS6-4.096#TRPBF LTQB 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-5#PBF LT1790ACS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-5#PBF LT1790AIS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-5#PBF LT1790BCS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-5#PBF LT1790BIS6-5#TRPBF LTQC 6-Lead Plastic TSOT-23 –40°C to 85°C
Input Voltage .............................................................20V
Specifi ed Temperature Range
Commercial............................................. 0°C to 70°C
Industrial .............................................–40°C to 85°C
Output Short-Circuit Duration .......................... Indefi nite
Operating Temperature Range
(Note 2) ..................................................–40°C to 125°C
Storage Temperature Range
(Note 3) ..................................................–65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
1
2
3
6
5
4
TOP VIEW
S6 PACKAGE
6-LEAD PLASTIC TSOT-23
TJMAX = 150°C, θJA = 230°C/W
*DNC: DO NOT CONNECT
VOUT
DNC*
VIN
GND
GND
DNC*
LT1790
3
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ORDER INFORMATION
LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE
LT1790ACS6-1.25 LT1790ACS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-1.25 LT1790AIS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-1.25 LT1790BCS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-1.25 LT1790BIS6-1.25#TR LTXT 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-2.048 LT1790ACS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-2.048 LT1790AIS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-2.048 LT1790BCS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-2.048 LT1790BIS6-2.048#TR LTXU 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-2.5 LT1790ACS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-2.5 LT1790AIS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-2.5 LT1790BCS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-2.5 LT1790BIS6-2.5#TR LTPZ 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-3 LT1790ACS6-3#TR LTQA 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-3 LT1790AIS6-3#TR LTQA 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-3 LT1790BCS6-3#TR LTQA 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-3 LT1790BIS6-3#TR LTQA 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-3.3 LT1790ACS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-3.3 LT1790AIS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-3.3 LT1790BCS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-3.3 LT1790BIS6-3.3#TR LTXW 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-4.096 LT1790ACS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-4.096 LT1790AIS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-4.096 LT1790BCS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-4.096 LT1790BIS6-4.096#TR LTQB 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790ACS6-5 LT1790ACS6-5#TR LTQC 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790AIS6-5 LT1790AIS6-5#TR LTQC 6-Lead Plastic TSOT-23 –40°C to 85°C
LT1790BCS6-5 LT1790BCS6-5#TR LTQC 6-Lead Plastic TSOT-23 0°C to 70°C
LT1790BIS6-5 LT1790BIS6-5#TR LTQC 6-Lead Plastic TSOT-23 –40°C to 85°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi ed by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
LT1790
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AVAILABLE OPTIONS
OUTPUT
VOLTAGE
INITIAL
ACCURACY
TEMPERATURE
COEFFICIENT
TEMPERATURE RANGE
0°C TO 70°C –40°C TO 85°C
ORDER PART NUMBER ORDER PART NUMBER
1.250V 0.05%
0.1%
10ppm/°C
25ppm/°C
LT1790ACS6-1.25
LT1790BCS6-1.25
LT1790AIS6-1.25
LT1790BIS6-1.25
2.048V 0.05%
0.1%
10ppm/°C
25ppm/°C
LT1790ACS6-2.048
LT1790BCS6-2.048
LT1790AIS6-2.048
LT1790BIS6-2.048
2.500V 0.05%
0.1%
10ppm/°C
25ppm/°C
LT1790ACS6-2.5
LT1790BCS6-2.5
LT1790AIS6-2.5
LT1790BIS6-2.5
3.000V 0.05%
0.1%
10ppm/°C
25ppm/°C
LT1790ACS6-3
LT1790BCS6-3
LT1790AIS6-3
LT1790BIS6-3
3.300V 0.05%
0.1%
10ppm/°C
25ppm/°C
LT1790ACS6-3.3
LT1790BCS6-3.3
LT1790AIS6-3.3
LT1790BIS6-3.3
4.096V 0.05%
0.1%
10ppm/°C
25ppm/°C
LT1790ACS6-4.096
LT1790BCS6-4.096
LT1790AIS6-4.096
LT1790BIS6-4.096
5.000V 0.05%
0.1%
10ppm/°C
25ppm/°C
LT1790ACS6-5
LT1790BCS6-5
LT1790AIS6-5
LT1790BIS6-5
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Notes 3, 4) LT1790A 1.24937
–0.05
1.25 1.25062
0.05
V
%
LT1790B 1.24875
–0.1
1.25 1.25125
0.1
V
%
LT1790AC l
l
1.24850
–0.12
1.25 1.2515
0.12
V
%
LT1790AI l
l
1.24781
–0.175
1.25 1.25219
0.175
V
%
LT1790BC l
l
1.24656
–0.275
1.25 1.25344
0.275
V
%
LT1790BI l
l
1.24484
–0.4125
1.25 1.25516
0.4125
V
%
Output Voltage Temperature Coeffi cient (Note 5) TMIN ≤ TA ≤ TMAX
LT1790A
LT1790B
l
l
5
12
10
25
ppm/°C
ppm/°C
Line Regulation 2.6V ≤ VIN ≤ 18V
l
50 170
220
ppm/V
ppm/V
Load Regulation (Note 6) IOUT Source = 5mA, VIN = 2.8V
l
100 160
250
ppm/mA
ppm/mA
IOUT Sink = 1mA, VIN = 3.2V
l
120 180
250
ppm/mA
ppm/mA
Minimum Operating Voltage (Note 7) VIN, ΔVOUT = 0.1%
I
OUT = 0mA
I
OUT Source = 5mA
I
OUT Sink = 1mA
l
l
l
1.95 2.15
2.50
2.90
2.95
V
V
V
V
1.25V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed
temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 2.6V, unless otherwise noted.
LT1790
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PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply Current No Load
l
35 60
75
μA
μA
Minimum Operating Current—
Negative Output (See Figure 7)
VOUT = –1.25V, ±0.1% 100 125 μA
Turn-On Time CLOAD = 1μF 250 μs
Output Noise (Note 8) 0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
10
14
μVP-P
μVRMS
Long-Term Drift of Output Voltage (Note 9) 50 ppm/√kHr
Hysteresis (Note 10) ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
l
l
25
40
ppm
ppm
1.25V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed
temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 2.6V, unless otherwise noted.
2.048V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the
specifi ed temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 2.8V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Notes 3, 4) LT1790A 2.04697
–0.05
2.048 2.04902
0.05
V
%
LT1790B 2.04595
–0.1
2.048 2.05005
0.1
V
%
LT1790AC l
l
2.04554
–0.12
2.048 2.05046
0.12
V
%
LT1790AI l
l
2.04442
–0.175
2.048 2.05158
0.175
V
%
LT1790BC l
l
2.04237
–0.275
2.048 2.05363
0.275
V
%
LT1790BI l
l
2.03955
–0.4125
2.048 2.05645
0.4125
V
%
Output Voltage Temperature Coeffi cient (Note 5) TMIN ≤ TA ≤ TMAX
LT1790A
LT1790B
l
l
5
12
10
25
ppm/°C
ppm/°C
Line Regulation 2.8V ≤ VIN ≤ 18V
l
50 170
220
ppm/V
ppm/V
Load Regulation (Note 6) IOUT Source = 5mA
l
120 200
280
ppm/mA
ppm/mA
IOUT Sink = 3mA
l
130 260
450
ppm/mA
ppm/mA
Dropout Voltage (Note 7) VIN – VOUT, ΔVOUT = 0.1%
I
OUT = 0mA
I
OUT Source = 5mA
I
OUT Sink = 3mA
l
l
l
50 100
500
750
450
mV
mV
mV
mV
Supply Current No Load
l
35 60
75
μA
μA
Minimum Operating Current—
Negative Output (See Figure 7)
VOUT = –2.048V, 0.1% 100 125 μA
Turn-On Time CLOAD = 1μF 350 μs
LT1790
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2.5V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed
temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 3V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Notes 3, 4) LT1790A 2.49875
–0.05
2.5 2.50125
0.05
V
%
LT1790B 2.4975
–0.1
2.5 2.5025
0.1
V
%
LT1790AC l
l
2.4970
–0.12
2.5 2.5030
0.12
V
%
LT1790AI l
l
2.49563
–0.175
2.5 2.50438
0.175
V
%
LT1790BC l
l
2.49313
–0.275
2.5 2.50688
0.275
V
%
LT1790BI l
l
2.48969
–0.4125
2.5 2.51031
0.4125
V
%
Output Voltage Temperature Coeffi cient (Note 5) TMIN ≤ TA ≤ TMAX
LT1790A
LT1790B
l
l
5
12
10
25
ppm/°C
ppm/°C
Line Regulation 3V ≤ VIN ≤ 18V
l
50 170
220
ppm/V
ppm/V
Load Regulation (Note 6) IOUT Source = 5mA
l
80 160
250
ppm/mA
ppm/mA
IOUT Sink = 3mA
l
70 110
300
ppm/mA
ppm/mA
Dropout Voltage (Note 7) VIN – VOUT, ΔVOUT = 0.1%
I
OUT = 0mA
I
OUT Source = 5mA
I
OUT Sink = 3mA
l
l
l
50 100
120
450
250
mV
mV
mV
mV
Supply Current No Load
l
35 60
80
μA
μA
Minimum Operating Current—
Negative Output (See Figure 7)
VOUT = –2.5V, 0.1% 100 125 μA
Turn-On Time CLOAD = 1μF 700 μs
Output Noise (Note 8) 0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
32
48
μVP-P
μVRMS
Long-Term Drift of Output Voltage (Note 9) 50 ppm/√kHr
Hysteresis (Note 10) ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
l
l
25
40
ppm
ppm
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Noise (Note 8) 0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
22
41
μVP-P
μVRMS
Long-Term Drift of Output Voltage (Note 9) 50 ppm/√kHr
Hysteresis (Note 10) ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
l
l
25
40
ppm
ppm
2.048V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the
specifi ed temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 2.8V, unless otherwise noted.
LT1790
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3V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed
temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 3.5V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Notes 3, 4) LT1790A 2.9985
–0.05
3 3.0015
0.05
V
%
LT1790B 2.9970
–0.10
3 3.0030
0.10
V
%
LT1790AC l
l
2.99640
–0.12
3 3.00360
0.12
V
%
LT1790AI l
l
2.99475
–0.175
3 3.00525
0.175
V
%
LT1790BC l
l
2.99175
–0.275
3 3.00825
0.275
V
%
LT1790BI l
l
2.98763
–0.4125
3 3.01238
0.4125
V
%
Output Voltage Temperature Coeffi cient (Note 5) TMIN ≤ TA ≤ TMAX
LT1790A
LT1790B
l
l
5
12
10
25
ppm/°C
ppm/°C
Line Regulation 3.5V ≤ VIN ≤ 18V
l
50 170
220
ppm/V
ppm/V
Load Regulation (Note 6) IOUT Source = 5mA
l
80 160
250
ppm/mA
ppm/mA
IOUT Sink = 3mA
l
70 110
300
ppm/mA
ppm/mA
Dropout Voltage (Note 7) VIN – VOUT
, ΔVOUT = 0.1%
I
OUT = 0mA
I
OUT Source = 5mA
I
OUT Sink = 3mA
l
l
l
50 100
120
450
250
mV
mV
mV
mV
Supply Current No Load
l
35 60
80
μA
μA
Minimum Operating Current—
Negative Output (See Figure 7)
VOUT = –3V, 0.1% 100 125 μA
Turn-On Time CLOAD = 1μF 700 μs
Output Noise (Note 8) 0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
50
56
μVP-P
μVRMS
Long-Term Drift of Output Voltage (Note 9) 50 ppm/√kHr
Hysteresis (Note 10) ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
l
l
25
40
ppm
ppm
LT1790
8
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3.3V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed
temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 3.8V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Notes 3, 4) LT1790A 3.29835
–0.05
3.3 3.30165
0.05
V
%
LT1790B 3.2967
–0.10
3.3 3.3033
0.10
V
%
LT1790AC l
l
3.29604
–0.120
3.3 3.30396
0.120
V
%
LT1790AI l
l
3.29423
–0.175
3.3 3.30578
0.175
V
%
LT1790BC l
l
3.29093
–0.275
3.3 3.30908
0.275
V
%
LT1790BI l
l
3.28639
–0.4125
3.3 3.31361
0.4125
V
%
Output Voltage Temperature Coeffi cient (Note 5) TMIN ≤ TA ≤ TMAX
LT1790A
LT1790B
l
l
5
12
10
25
ppm/°C
ppm/°C
Line Regulation 3.8V ≤ VIN ≤ 18V
l
50 170
220
ppm/V
ppm/V
Load Regulation (Note 6) IOUT Source = 5mA
l
80 160
250
ppm/mA
ppm/mA
IOUT Sink = 3mA
l
70 110
300
ppm/mA
ppm/mA
Dropout Voltage (Note 7) VIN – VOUT, ΔVOUT = 0.1%
I
OUT = 0mA
I
OUT Source = 5mA
I
OUT Sink = 3mA
l
l
l
50 100
120
450
250
mV
mV
mV
mV
Supply Current No Load
l
35 60
80
μA
μA
Minimum Operating Current—
Negative Output (See Figure 7)
VOUT = –3.3V, 0.1% 100 125 μA
Turn-On Time CLOAD = 1μF 700 μs
Output Noise (Note 8) 0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
50
67
μVP-P
μVRMS
Long-Term Drift of Output Voltage (Note 9) 50 ppm/√kHr
Hysteresis (Note 10) ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
l
l
25
40
ppm
ppm
LT1790
9
1790fb
4.096V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the
specifi ed temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 4.6V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Notes 3, 4) LT1790A 4.094
–0.05
4.096 4.098
0.05
V
%
LT1790B 4.092
–0.10
4.096 4.10
0.10
V
%
LT1790AC l
l
4.09108
–0.120
4.096 4.10092
0.120
V
%
LT1790AI l
l
4.08883
–0.175
4.096 4.10317
0.175
V
%
LT1790BC l
l
4.08474
–0.275
4.096 4.10726
0.275
V
%
LT1790BI l
l
4.07910
–0.4125
4.096 4.11290
0.4125
V
%
Output Voltage Temperature Coeffi cient (Note 5) TMIN ≤ TA ≤ TMAX
LT1790A
LT1790B
l
l
5
12
10
25
ppm/°C
ppm/°C
Line Regulation 4.6V ≤ VIN ≤ 18V
l
50 170
220
ppm/V
ppm/V
Load Regulation (Note 6) IOUT Source = 5mA
l
80 160
250
ppm/mA
ppm/mA
IOUT Sink = 3mA
l
70 110
300
ppm/mA
ppm/mA
Dropout Voltage (Note 7) VIN – VOUT
, ΔVOUT = 0.1%
I
OUT = 0mA
I
OUT Source = 5mA
I
OUT Sink = 3mA
l
l
l
50 100
120
450
250
mV
mV
mV
mV
Supply Current No Load
l
35 60
80
μA
μA
Minimum Operating Current—
Negative Output (See Figure 7)
VOUT = –4.096V, 0.1% 100 125 μA
Turn-On Time CLOAD = 1μF 700 μs
Output Noise (Note 8) 0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
60
89
μVP-P
μVRMS
Long-Term Drift of Output Voltage (Note 9) 50 ppm/√kHr
Hysteresis (Note 10) ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
l
l
25
40
ppm
ppm
LT1790
10
1790fb
5V ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the specifi ed
temperature range, otherwise specifi cations are at TA = 25°C. CL = 1μF and VIN = 5.5V, unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Voltage (Notes 3, 4) LT1790A 4.9975
–0.05
5 5.0025
0.05
V
%
LT1790B 4.995
–0.10
5 5.005
0.10
V
%
LT1790AC l
l
4.99400
–0.120
5 5.00600
0.120
V
%
LT1790AI l
l
4.99125
–0.175
5 5.00875
0.175
V
%
LT1790BC l
l
4.98625
–0.275
5 5.01375
0.275
V
%
LT1790BI l
l
4.97938
–0.4125
5 5.02063
0.4125
V
%
Output Voltage Temperature Coeffi cient (Note 5) TMIN ≤ TA ≤ TMAX
LT1790A
LT1790B
l
l
5
12
10
25
ppm/°C
ppm/°C
Line Regulation 5.5V ≤ VIN ≤ 18V
l
50 170
220
ppm/V
ppm/V
Load Regulation (Note 6) IOUT Source = 5mA
l
80 160
250
ppm/mA
ppm/mA
IOUT Sink = 3mA
l
70 110
300
ppm/mA
ppm/mA
Dropout Voltage (Note 7) VIN – VOUT
, ΔVOUT = 0.1%
I
OUT = 0mA
I
OUT Source = 5mA
I
OUT Sink = 3mA
l
l
l
50 100
120
450
250
mV
mV
mV
mV
Supply Current No Load
l
35 60
80
μA
μA
Minimum Operating Current—
Negative Output (See Figure 7)
VOUT = –5V, 0.1% 100 125 μA
Turn-On Time CLOAD = 1μF 700 μs
Output Noise (Note 8) 0.1Hz ≤ f ≤ 10Hz
10Hz ≤ f ≤ 1kHz
80
118
μVP-P
μVRMS
Long-Term Drift of Output Voltage (Note 9) 50 ppm/√kHr
Hysteresis (Note 10) ΔT = 0°C to 70°C
ΔT = –40°C to 85°C
l
l
25
40
ppm
ppm
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT1790 is guaranteed functional over the operating
temperature range of –40°C to 125°C. The LT1790-1.25 at 125°C is
typically less than 2% above the nominal voltage. The other voltage
options are typically less than 0.25% above their nominal voltage.
Note 3: If the part is stored outside of the specifi ed temperature range, the
output voltage may shift due to hysteresis.
Note 4: ESD (Electrostatic Discharge) sensitive device. Extensive use of
ESD protection devices are used internal to the LT1790, however, high
electrostatic discharge can damage or degrade the device. Use proper ESD
handling precautions.
Note 5: Temperature coeffi cient is measured by dividing the change in
output voltage by the specifi ed temperature range. Incremental slope is
also measured at 25°C.
Note 6: Load regulation is measured on a pulse basis from no load to the
specifi ed load current. Output changes due to die temperature change
must be taken into account separately.
Note 7: Excludes load regulation errors.
LT1790
11
1790fb
1.25V TYPICAL PERFORMANCE CHARACTERISTICS
TEMPERATURE (°C)
–50
1.247
OUTPUT VOLTAGE (V)
1.248
1.249
1.250
1.251
–10 30 70 110
17091.25 G01
1.252
1.253
–30 10 50 90
FOUR TYPICAL PARTS
INPUT-OUTPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
10
17901.25 G02
0.1
1
0.5 2.521.51
0
TA = 125°C TA = –55°C
TA = 25°C
TEMPERATURE (°C)
–50
0
VOLTAGE DIFFERENTIAL (V)
0.1
0.3
0.4
0.5
1.0
0.7
–10 30 50 130
17091.25 G03
0.2
0.8
0.9
0.6
–30 10 70 90 110
5mA100μA
1mA
OUTPUT CURRENT (mA)
0.1
–2000
OUTPUT VOLTAGE CHANGE (ppm)
–1600
–1200
–800
–400
110
17901.25 G04
0
–1800
–1400
–1000
–600
–200
TA = –55°C
TA = 25°C
TA = 125°C
OUTPUT CURRENT (mA)
0.1
0
OUTPUT VOLTAGE CHANGE (ppm)
400
800
1200
1600
110
17901.25 G05
2000
200
600
1000
1400
1800
TA = –55°C
TA = 25°C
TA = 125°C
INPUT VOLTAGE (V)
SUPPLY CURRENT (μA)
60
80
100
15
17901.25 G06
40
20
50
70
90
30
10
05
010 20
TA = –55°C
TA = 25°C
TA = 125°C
Output Voltage Temperature Drift
Load Regulation (Sourcing)
Minimum Input-Output Voltage
Differential (Sourcing)
Minimum Input-Output Voltage
Differential (Sinking)
Load Regulation (Sinking) Supply Current vs Input Voltage
Note 8: Peak-to-peak noise is measured with a single pole highpass fi lter
at 0.1Hz and a 2-pole lowpass fi lter at 10Hz. The unit is enclosed in a still
air environment to eliminate thermocouple effects on the leads. The test
time is 10 seconds. Integrated RMS noise is measured from 10Hz to 1kHz
with the HP3561A analyzer.
Note 9: Long-term drift typically has a logarithmic characteristic and
therefore changes after 1000 hours tend to be smaller than before that
time. Long-term drift is affected by differential stress between the IC and
the board material created during board assembly. See the Applications
Information section.
Note 10: Hysteresis in the output voltage is created by package stress that
differs depending on whether the IC was previously at a higher or lower
temperature. Output voltage is always measured at 25°C, but the IC is
cycled to 85°C or –40°C before a successive measurements. Hysteresis
is roughly proportional to the square of the temperature change.
Hysteresis is not a problem for operational temperature excursions where
the instrument might be stored at high or low temperature. See the
Applications Information section.
ELECTRICAL CHARACTERISTICS
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
12
1790fb
1.25V TYPICAL PERFORMANCE CHARACTERISTICS
INPUT VOLTAGE (V)
0
OUTPUT VOLTAGE (V)
1.255
1.265
1.275
1.285
16
17901.25. G07
1.245
1.235
1.250
1.260
1.270
1.280
1.240
1.230
1.225 4812
218
610 14 20
TA = –55°C
TA = 25°C
TA = 125°C
FREQUENCY (Hz)
–60
POWER SUPPLY REJECTION RATIO (dB)
0
10
–70
–80
–10
–40
–20
–30
–50
100 10k 100k 1M
17901.25 G08
–90 1k
VIN = 3V
CL = 1μF
FREQUENCY (Hz)
1
OUTPUT IMPEDANCE (Ω)
10
100
100 10k 100k
17901.25 G09
01k
500 VIN = 3V
CL = 0.47μF
CL = 4.7μF
CL = 1μF
OUTPUT TO GROUND VOLTAGE (V)
0
CURRENT IN RL (mA)
0.10
0.20
0.30
0.05
0.15
0.25
–2.0 –1.5 –1.0 –0.5
17091.25 G10
0–2.5
–VEE
VOUT
3V
RL
5k
4
21
6
1μF
LT1790-1.25
R1 10k
TA = 25°C
TA = 125°C
TA = –55°C
HOURS
0
ppm
60
100
140
800
17901.25 G11
20
–20
40
80
120
0
–40
–60 200 400 600 1000
LT1790S6-1.25V
2 TYPICAL PARTS SOLDERED TO PCB
TA = 30°C
TIME (SEC)
0
OUTPUT NOISE (5μV/DIV)
8
17901.25 G12
246 107135 9
FREQUENCY (Hz)
10
2.0
NOISE VOLTAGE (μV/√Hz)
2.5
3.0
3.5
4.0
100 1k 10k
17901.25 G13
1.5
1.0
0.5
0
4.5
5.0 CL = 1μF
IO = 100μA
IO = 0μA
IO = 250μA
IO = 1mA
FREQUENCY (Hz)
1
INTEGRATED NOISE (μVRMS)
10
100
10010 1000
17901.25 G14
Line Regulation Output Impedance vs Frequency
Power Supply Rejection Ratio
vs Frequency
–1.25V Characteristics
Long-Term Drift
(Data Points Reduced After 500 Hr) Output Noise 0.1Hz to 10Hz
Output Voltage Noise Spectrum Integrated Noise 10Hz to 1kHz
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
13
1790fb
2.048V TYPICAL PERFORMANCE CHARACTERISTICS
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
70 90 110
2.056
2.054
2.052
2.050
2.048
2.046
2.044
2.042
17902.048 G01
–30 –10 10 30 50 130
FOUR TYPICAL PARTS
INPUT-OUTPUT VOLTAGE (V)
0.1
0.1
1
10
0.3
17902.048 G02
OUTPUT CURRENT (mA)
00.70.2 0.4 0.5 0.6
TA = 25°C TA = 125°C
TA = –55°C
TEMPERATURE (°C)
–50
–50
VOLTAGE DIFFERENTIAL (mV)
–30
10
30
50
70
130
17902.048 G03
–10
10 130
50
–10 110
30
–30 90
70
90
110
5mA
1mA
100μA
OUTPUT CURRENT (mA)
0.1
–2000
OUTPUT VOLTAGE CHANGE (ppm)
–1600
–1200
–800
–400
110
17902.048 G04
0
–1800
–1400
–1000
–600
–200
TA = 25°C
TA = 125°C
TA = –55°C
OUTPUT CURRENT (mA)
0.1
0
OUTPUT VOLTAGE CHANGE (ppm)
400
800
1200
1600
110
17902.048 G05
2000
200
600
1000
1400
1800
TA = –40°C
TA = 25°C
TA = 125°C
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (μA)
40
50
60
20
17902.048 G06
30
20
0510 15
10
80
70 TA = –55°C
TA = 25°C
TA = 125°C
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
2.054
2.052
2.050
2.048
2.046
2.044
2.042 4 8 12 16
17902.048 G07
2020 6 10 14 18
TA = –55°C
TA = 25°C
TA = 125°C
FREQUENCY (Hz)
–60
POWER SUPPLY REJECTION RATIO (dB)
10
0
20
–70
–80
–10
–40
–20
–30
–50
100 10k 100k 1M
17902.048 G08
1k
CL = 1μF
FREQUENCY (Hz)
10k
1
OUTPUT IMPEDANCE (Ω)
10
100
1000
100k 1M 10M
17902.048 G09
CL = 0.47μF
CL = 4.7μF
CL = 1μF
Output Voltage Temperature Drift
Load Regulation (Sourcing)
Minimum Input-Output Voltage
Differential (Sourcing)
Minimum Input-Output Voltage
Differential (Sinking)
Load Regulation (Sinking) Supply Current vs Input Voltage
Line Regulation Output Impedance vs Frequency
Power Supply Rejection Ratio
vs Frequency
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
14
1790fb
2.048V TYPICAL PERFORMANCE CHARACTERISTICS
–2.048V Characteristics Long-Term Drift
Output Noise 0.1Hz to 10Hz Output Voltage Noise Spectrum
Integrated Noise 10Hz to 1kHz
OUTPUT TO GROUND VOLTAGE (V)
0
CURRENT IN RL (mA)
0.10
0.20
0.30
0.05
0.15
0.25
–3.5 –3 –2.5 –2 –1.5 –1 –0.5
17092.048 G10
0–4
–VEE
VOUT
3V
RL
5k
4
21
6
1μF
LT1790-2.048
R1 10k
TA = 125°C
TA = 25°C
TA = –55°C
HOURS
0
ppm
60
100
800
17902.048 G11
20
–20
40
80
0
–40
–60
–80
–100 200 400 600 1000
TA = 30°C
2 TYPICAL PARTS SOLDERED TO PCB
TIME (SEC)
0
OUTPUT NOISE (10μV/DIV)
8
17902.048 G12
246 107135 9
FREQUENCY (Hz)
10
4
NOISE VOLTAGE (μV/√Hz)
5
6
7
8
100 1k 10k
17902.048 G13
3
2
1
0
9
10 CL = 1μF
IO = 100μA
IO = 0μA
IO = 250μA
IO = 1mA
FREQUENCY (Hz)
1
INTEGRATED NOISE (μVRMS)
10
100
10010 1000
17902.048 G14
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
15
1790fb
2.5 TYPICAL PERFORMANCE CHARACTERISTICS
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
30 70
17902.5 G01
–30 –10 50 90 110
2.508
2.506
2.504
2.502
2.500
2.498
2.496
2.494 10 130
FOUR TYPICAL PARTS
INPUT-OUTPUT VOLTAGE (V)
0 0.1 0.2
0.1
OUTPUT CURRENT (mA)
1
10
0.3 0.4 0.5 0.6
17902.5 G02
TA = –55°C TA = 125°C
TA = 25°C
TEMPERATURE (°C)
–50
–30
VOLTAGE DIFFERENTIAL (mV)
–10
30
50
70
–10 30 50 130
17902.5 G03
10
–30 10 70 90 110
90
100μA
5mA
1mA
OUTPUT CURRENT (mA)
0.1
–2000
OUTPUT VOLTAGE CHANGE (ppm)
–1600
–1200
–800
–400
110
17902.5 G04
0
–1800
–1400
–1000
–600
–200 TA = 25°C
TA = 125°C
TA = –55°C
OUTPUT CURRENT (mA)
0.1
0
OUTPUT VOLTAGE CHANGE (ppm)
400
800
1200
1600
110
17902.5 G05
2000
200
600
1000
1400
1800
TA = –55°C
TA = 25°C
TA = 125°C
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (μA)
40
50
60
20
17902.5 G06
30
20
0510 15
10
80
70 TA = –55°C
TA = 25°C
TA = 125°C
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
2.515
2.510
2.505
2.500
2.495
2.490
2.489 4 8 12 16
17902.5 G07
2020 6 10 14 18
TA = –55°C
TA = 25°C
TA = 125°C
FREQUENCY (Hz)
POWER SUPPLY REJECTION RATIO (dB)
–40
–20
–30
0
20
–50
–80
–60
–70
–10
10
100 10k 100k 1M
17902.5 G08
1k
CL = 1μF
FREQUENCY (Hz)
100
1
OUTPUT IMPEDANCE (Ω)
10
100
1000
1k 10k 100k
17902.5 G09
CL = 4.7μF
CL = 0.47μF
CL = 1μF
Output Voltage Temperature Drift
Load Regulation (Sourcing)
Minimum Input-Output Voltage
Differential (Sinking)
Load Regulation (Sinking) Supply Current vs Input Voltage
Line Regulation Output Impedance vs Frequency
Power Supply Rejection Ratio
vs Frequency
Minimum Input-Output Voltage
Differential (Sourcing)
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
16
1790fb
2.5V TYPICAL PERFORMANCE CHARACTERISTICS
–2.5V Characteristics
Long-Term Drift
(Data Points Reduced After 500 Hr)
Output Noise 0.1Hz to 10Hz Output Voltage Noise Spectrum
OUTPUT TO GROUND VOLTAGE (V)
0
0
CURRENT IN R
L
(mA)
0.05
0.10
0.15
0.20
–1.0–2.0–3.0
–4.0
17902.5 G10
0.25
0.30
–0.5–1.5–2.5
–3.5
T
A
= 25°C
T
A
= 125°C
T
A
= –55°C
–V
EE
V
OUT
3V
R
L
5k
4
1, 2
6
1μF
LT1790-2.5
R1 10k
TIME (SEC)
0
OUTPUT NOISE (10μV/DIV)
8
17902.5 G12
246 107135 9
HOURS
0
ppm
60
100
140
800
17902.5 G11
20
–20
40
80
120
0
–40
–60 200 400 600 1000
T
A
= 30°C
2 TYPICAL PARTS SOLDERED TO PCB
Integrated Noise 10Hz to 1kHz
FREQUENCY (Hz)
10
NOISE VOLTAGE (μV/√Hz)
10
8
6
4
2
0100 1k 10k
17902.5 G13
C
L
= 1μF
I
O
= 0μA
I
O
= 1mA
I
O
= 250μA
FREQUENCY (Hz)
1
INTEGRATED NOISE (μV
RMS
)
10
100
10010 1000
17902.5 G14
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
17
1790fb
5V TYPICAL PERFORMANCE CHARACTERISTICS
Output Voltage Temperature Drift
Load Regulation (Sourcing)
Minimum Input-Output Voltage
Differential (Sourcing)
Minimum Input-Output Voltage
Differential (Sinking)
Load Regulation (Sinking) Supply Current vs Input Voltage
Line Regulation Output Impedance vs Frequency
Power Supply Rejection Ratio
vs Frequency
TEMPERATURE (°C)
–50
OUTPUT VOLTAGE (V)
5.005
5.010
5.015
110
17905 G01
5.000
4.995
4.985 –10 30 70
–30 130
10 50 90
4.990
5.025
5.020
FOUR TYPICAL PARTS
INPUT-OUTPUT VOLTAGE (V)
0 0.1 0.2
0.1
OUTPUT CURRENT (mA)
1
10
0.3 0.4 0.5 0.6
17905 G02
TA = –55°C
TA = 125°C
TA = 25°C
TEMPERATURE (°C)
–50
–50
VOLTAGE DIFFERENTIAL (mV)
–10
10
30
70
90
17905 G03
–30
–10 30
–30 90
10 50 130110
50
70
100μA
1mA
5mA
OUTPUT CURRENT (mA)
0.1
–2000
OUTPUT VOLTAGE CHANGE (ppm)
–1600
–1200
–800
–400
110
17905 G04
0
–1800
–1400
–1000
–600
–200
TA = 25°C
TA = 125°C
TA = –55°C
OUTPUT CURRENT (mA)
0.1
0
OUTPUT VOLTAGE CHANGE (ppm)
400
800
1200
1600
110
17905 G05
2000
200
600
1000
1400
1800
TA = –40°C
TA = 25°C
TA = 125°C
INPUT VOLTAGE (V)
0
SUPPLY CURRENT (μA)
40
50
60
20
17905 G06
30
20
0510 15
10
80
70 TA = –55°C
TA = 25°C
TA = 125°C
FREQUENCY (Hz)
–60
POWER SUPPLY REJECTION RATIO (dB)
10
0
20
–70
–80
–10
–40
–20
–30
–50
100 10k 100k 1M
17905 G08
1k
CL = 1μF
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
5.04
5.02
5.00
4.98
4.96
4.94
4.92 4 8 12 16
17905 G07
2020 6 10 14 18
TA = –55°C
TA = 25°C
TA = 125°C
FREQUENCY (Hz)
100
1
OUTPUT IMPEDANCE (Ω)
10
100
1000
1k 10k 100k
17905 G09
CL = 4.7μF
CL = 0.47μF
CL = 1μF
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
18
1790fb
5V TYPICAL PERFORMANCE CHARACTERISTICS
–5V Characteristics Long-Term Drift
Output Noise 0.1Hz to 10Hz Output Voltage Noise Spectrum
Integrated Noise 10Hz to 1kHz
OUTPUT TO GROUND VOLTAGE (V)
0
CURRENT IN RL (mA)
0.10
0.20
0.30
0.05
0.15
0.25
–8 –6 –4 –2
17905 G10
0–9–10 –7 –5 –3 –1
–VEE
VOUT
5.5V
RL
5k
4
21
6
1μF
LT1790-5
R1 10k
TA = –55°C
TA = 125°C
TA = 25°C
HOURS
0
ppm
60
100
800
17905 G11
20
–20
40
80
0
–40
–60
–80
–100 200 400 600 1000
TA = 30°C
2 TYPICAL PARTS SOLDERED TO PCB
TIME (SEC)
0
OUTPUT NOISE (20μV/DIV)
8
17905 G12
246 107135 9
FREQUENCY (Hz)
10
NOISE VOLTAGE (μV/√Hz)
10
8
6
4
2
0100 1k 10k
17905 G13
CL = 1μF
IO = 0μA
IO = 1mA
IO = 250μA
FREQUENCY (Hz)
10
INTEGRATED NOISE (μVRMS)
1000
100
10
1100 1000
17905 G14
Each of the voltage options have similar performance curves. For the 3V, 3.3V and the 4.096V options,
the curves can be estimated based on the 2.5V and 5V curves.
LT1790
19
1790fb
APPLICATIONS INFORMATION
Bypass and Load Capacitors
The LT1790 voltage references should have an input bypass
capacitor of 0.1μF or larger, however the bypassing of other
local devices may serve as the required component. These
references also require an output capacitor for stability.
The optimum output capacitance for most applications
is 1μF, although larger values work as well. This capaci-
tor affects the turn-on and settling time for the output to
reach its fi nal value.
All LT1790 voltages perform virtually the same, so the
LT1790-2.5 is used as an example.
Figure 1 shows the turn-on time for the LT1790-2.5 with a
1μF input bypass and 1μF load capacitor. Figure 2 shows
the output response to a 0.5V transient on VIN with the
same capacitors.
The test circuit of Figure 3 is used to measure the stability
of various load currents. With RL = 1k, the 1V step produces
a current step of 1mA. Figure 4 shows the response to a
± 0.5mA load. Figure 5 is the output response to a sourcing
step from 4mA to 5mA, and Figure 6 is the output response
of a sinking step from –4mA to –5mA.
Figure 1. Turn-On Characteristics of LT1790-2.5 Figure 2. Output Response to 0.5V Ripple on VIN
Figure 3. Response Time Test Circuit
Figure 4. LT1790-2.5 Sourcing and Sinking 0.5mA Figure 5. LT1790-2.5 Sourcing 4mA to 5mA
LT1790-2.5
C
IN
0.1μF
C
L
1μF V
GEN
1790 F03
1V
V
IN
3V
4
1, 2
1k
6
1790 F01
3V VIN
VOUT
2V
0V
1V
1790 F02
3V VIN
VOUT
2V
0V
1V
1790 F04
VGEN
VOUT
(AC COUPLED)
3V
2V
1790 F05
VGEN
VOUT
(AC COUPLED)
–3V
–2V
LT1790
20
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APPLICATIONS INFORMATION
Figure 6. LT1790-2.5 Sinking – 4mA to –5mA
Positive or Negative Operation
Series operation is ideal for extending battery life. If an
LT1790 is operated in series mode it does not require an
external current setting resistor. The specifi cations guar-
antee that the LT1790 family operates to 18V. When the
circuitry being regulated does not demand current, the
series connected LT1790 consumes only a few hundred
μW, yet the same connection can sink or source 5mA of
load current when demanded. A typical series connection
is shown on the front page of this data sheet.
The circuit in Figure 7 shows the connection for a –2.5V
reference, although any LT1790 voltage option can be
confi gured this way to make a negative reference. The
LT1790 can be used as very stable negative references,
however, they require a positive voltage applied to Pin 4
to bias internal circuitry. This voltage must be current
limited with R1 to keep the output PNP transistor from
turning on and driving the grounded output. C1 provides
stability during load transients. This connection maintains
nearly the same accuracy and temperature coeffi cient of
the positive connected LT1790.
Long-Term Drift
Long-term drift cannot be extrapolated from accelerated
high temperature testing. This erroneous technique gives
drift numbers that are widely optimistic. The only way
long-term drift can be determined is to measure it over
the time interval of interest. The LT1790S6 drift data was
taken on over 100 parts that were soldered into PC boards
similar to a real world application. The boards were then
placed into a constant temperature oven with TA = 30°C,
their outputs scanned regularly and measured with an 8.5
digit DVM. Long-term drift curves are shown in the Typical
Performance Characteristics section.
LT1790-2.5
C
L
1μF
C1
0.1μF
1790 F07
4
1, 2
6
R1
10k
V
OUT
= –2.5V
V
EE
3V
R
L
= V
EE
– V
OUT
125μA
Figure 7. Using the LT1790-2.5 to Build a –2.5V Reference
1790 F06
VGEN
VOUT
(AC COUPLED)
6V
4V
2V
0V
8V
LT1790
21
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APPLICATIONS INFORMATION
Figure 9. Worst-Case –40°C to 85°C Hysteresis on 80 Units
Figure 8. Worst-Case 0°C to 70°C Hysteresis on 79 Units
Hysteresis
Hysteresis data shown in Figures 8 and 9 represent the
worst-case data taken on parts from 0°C to 70°C and from
–40°C to 85°C. Units were cycled several times over these
temperature ranges and the largest change is shown. As
expected, the parts cycled over the higher temperature
range have higher hysteresis than those cycled over the
lower range.
In addition to thermal hysteresis, the thermal shock as-
sociated with high temperature soldering may cause the
output to shift. For traditional PbSn solder temperatures,
the output shift of the LT1790 is typically just 150ppm
(0.015%).
DISTRIBUTION (ppm)
–60 –50 –40 –30 –20 –10 0 10 20 30 40 50 60
NUMBER OF UNITS
1790 F08
30
20
0
10
25
15
5
70°C TO 25°C 0°C TO 25°C
DISTRIBUTION (ppm)
–100 –80 –60 –40 –20 0 20 40 60 80 100
NUMBER OF UNITS
20
25
30
1790 F09
15
10
0
5
50
45
40
–40°C TO 25°C
80°C TO 25°C
35
For lead-free solder, IR reflow temperatures are much
higher, often 240°C to 260°C at the peak. As a result, the
packaging materials have been optimized to reduce VOUT
shift as possible during high temperature reflow. In addi-
tion, care should be taken when using lead-free solder to
minimize the peak temperature and dwell time as much
as is practical. A typical lead-free reflow profile is shown
in Figure 10. LT1790 units were heated using a similar
profile, with a peak temperature of 250°C. These parts
were run through the heating process 3 times to show the
cumulative effect of these heat cycles. Figure 11 shows
MINUTES
0246810
DEGREES (C)
150
120s
40s
tL
130s
RAMP
DOWN
tP
130s
1790 F10
75
0
300
225
380s TP = 260°
T = 150°C
T = 190°C
TS(MAX) = 200°C
TL = 217°C
RAMP TO
150°C
Figure 10. Lead-Free Refl ow Profi le
PPM
01020304050
NUMBER OF UNITS
4
5
6
1790 F11
3
2
0
1
9
8
7
Figure 11. 1X IR Refl ow Peak Temperature = 250°C,
Delta Output Voltage (ppm)
LT1790
22
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APPLICATIONS INFORMATION
the shift after 1 cycle, while Figure 12 shows shift after
3 cycles. In the worst case, shifts are typically 150ppm,
but may be as high as 290ppm. Shifts in output voltage
are proportional to temperature and dwell time.
In general, the output shift can be reduced or fully recov-
ered by a long (12-24 hour) bake of the completed PC
Board assembly at high temperature (100°C to 150C°)
after soldering to remove mechanical stress that has been
induced by thermal shock. Once the PC Boards have cooled
to room temperature, they may continue to shift for up to
3 times the bake time. This should be taken into account
before any calibration is performed.
Assuming 80μA max supply current for the LT1790, a
25μA load, 120mV max dropout and a 4V to 30V input
specifi cation, the largest that R1 can be is (4V – 3.3V
– 120mV)/(80μA + 25μA) = 5.5k. Furthermore, assum-
ing 220mW of dissipation in the 18V SOT-23 Zener, this
gives a max current of (220mW)/(18V) = 12.2mA. So the
smallest that R1 should be is (30V – 18V)/12.2mA = 1k,
rated at 150mW.
With R1 = 1k, and assuming a 450mV worst-case drop-
out, the LT1790 can deliver a minimum current of (4V
– 3.3V–450mV)/(1k) = 250μA. In Figure 13, R1 and C1
provide fi ltering of the Zener noise when the Zener is in
its noisy V-I knee.
There are other variations for higher voltage operation that
use a pass transistor shown in Figures 14 and 15. These
circuits allow the input voltage to be as high as 160V while
maintaining low supply current.
LT1790-3.3
4V TO 30V
C1
0.1μF
BZX84C18 1μF
VOUT
R1
1790 F13
Figure 13. Extended Supply Range Reference
PPM
2902702502302101901701501301109070
NUMBER OF UNITS
2.0
2.5
3.0
1790 F12
1.5
1.0
0
0.5
3.5
Figure 12. 3X IR Refl ow Peak Temperature = 250°C,
Delta Output Voltage (ppm)
LT1790
C1
0.1μF
C2
1μF
ON SEMI
MMBT5551
V
S
6V TO 160V
V
OUT
1790 F14
R2
4.7k
R1
330k
BZX84C12
Figure 14. Extended Supply Range Reference
Figure 15. Extended Supply Range Reference
Higher Input Voltage
The circuit in Figure 13 shows an easy way to increase the
input voltage range of the LT1790. The Zener diode can be
anywhere from 6V to 18V. For equal power sharing between
R1 and the Zener (at 30V), the 18V option is better. The
circuit can tolerate much higher voltages for short periods
and is suitable for transient protection.
LT1790
23
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APPLICATIONS INFORMATION
More Output Current
The circuit in Figure 16 is a compact, high output current,
low dropout precision supply. The circuit uses the SOT-23
LT1782 and the ThinSOT LT1790. Resistive divider R1 and
R2 set a voltage 22mV below VS. For under 1mA of output
current, the LT1790 supplies the load. Above 1mA of load
current, the (+) input of the LT1782 is pulled below the
22mV divider reference and the output FET turns on to
supply the load current. Capacitor C1 stops oscillations in
the transition region. The no load standing current is only
120μA, yet the output can deliver over 300mA.
Noise
An estimate of the total integrated noise from 10Hz to 1kHz
can be made by multiplying the fl at band spot noise by
√BW. For example, from the Typical Performance curves,
the LT1790-1.25 noise spectrum shows the average spot
noise to be about 450nV/√Hz. The square root of the
bandwidth is √990 = 31.4. The total noise 10Hz to 1kHz
noise is (450nV)(31.4) = 14.1μV. This agrees well with the
measured noise.
This estimate may not be as good with higher voltage
options, there are several reasons for this. Higher voltage
options have higher noise and they have higher variability
due to process variations. 10Hz to 1kHz noise may vary by
2dB on the LT1790-5 and 1dB on the LT1790-2.5.
Measured noise may also vary because of peaking in the
noise spectrum. This effect can be seen in the range of
1kHz to 10kHz with all voltage options sourcing different
load currents. From the Typical Performance curves the
10Hz to 1kHz noise spectrum of the LT1790-5 is shown
to be 3μV/√Hz at low frequency. The estimated noise is
(3μV)(31.4) = 93.4μV. The actual integrated 10Hz to 1kHz
noise measures 118.3μV. The peaking shown causes this
larger number. Peaking is a function of output capacitor
as well as load current and process variations.
–
+
LT1790-2.5
LT1782
17909 F16
C2
1μF
NOTE: NOT CURRENT LIMITED
VOUT = 2.5V
ILOAD = 0mA to 300mA
R3
22Ω
5%
R1
680Ω
5%
VS
2.8V TO 3.3V
NO LOAD
SUPPLY CURRENT
120μA
R2
100k
5%
C1
0.1μF
R4
1k
5% VISHAY SILICONIX
Si3445DV
Figure 16. Compact, High Output Current, Low Dropout, Precision 2.5V Supply
LT1790
24
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SIMPLIFIED SCHEMATIC
4VIN
6VOUT
1, 2 GND
1790 SS
LT1790
25
1790fb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PACKAGE DESCRIPTION
S6 Package
6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.30 – 0.45
6 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3) S6 TSOT-23 0302 REV B
2.90 BSC
(NOTE 4)
0.95 BSC
1.90 BSC
0.80 – 0.90
1.00 MAX 0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
PIN ONE ID
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
3.85 MAX
0.62
MAX
0.95
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
LT1790
26
1790fb
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2000
LT 0609 REV B • PRINTED IN USA
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–2.5V Negative 50mA Series Reference
No Load Supply Current
ICC = 1.6mA
IEE = 440μA
LT1790-2.5
1μF
2k
VZ = 5.1V
VCC = 5V
MPS2907A
VEE = –5V
5.1k
1790 TA03
4
1, 2
6
–2.5V
50mA