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LT1790

1790fa

Micropower SOT-23

Low Dropout Reference Family

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 com-

pensation to obtain a low temperature coefficient and

trimmed precision thin-film resistors to achieve high

output accuracy. In addition, each LT1790 is post-pack-

age trimmed to greatly reduce the temperature coefficient

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 supply

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.

■

Handheld Instruments

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Negative Voltage References

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Industrial Control Systems

■

Data Acquisition Systems

■

Battery-Operated Equipment

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High Accuracy:

A Grade—0.05% Max

B Grade—0.1% Max

■

Low Drift:

A Grade—10ppm/

C Max

B Grade—25ppm/

C Max

■

Low Profile (1mm) ThinSOT

Package

■

Low Supply Current: 60µA Max

■

Sinks and Sources Current

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Low Dropout Voltage

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Guaranteed Operational –40°C to 125°C

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Wide Supply Range to 18V

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Available Output Voltage Options: 1.25V, 2.048V,

2.5V, 3V, 3.3V, 4.096V and 5V

, LTC and LT are registered trademarks of Linear Technology Corporation.

Typical V

OUT

Distribution for LT1790-2.5

Positive Connection for LT1790-2.5

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

0.1µF

2.6V ≤ V

≤ 18V

1µF

1, 2

OUT

= 2.5V

LT1790-2.5

1790 TA01

OUTPUT VOLTAGE (V)

2.498 2.499 2.500 2.501 2.502

NUMBER OF UNITS

1790 TA02

LT1790B LIMITS

LT1790A LIMITS

167 UNITS

ThinSOT is a trademark of Linear Technology Corporation.

Summary of content (24 pages)

PAGE 1
LT1790 Micropower SOT-23 Low Dropout Reference Family U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO High Accuracy: A Grade—0.05% Max B Grade—0.1% Max Low Drift: A Grade—10ppm/°C Max B Grade—25ppm/°C Max Low Profile (1mm) ThinSOTTM Package Low Supply Current: 60µA Max Sinks and Sources Current Low Dropout Voltage Guaranteed Operational –40°C to 125°C Wide Supply Range to 18V Available Output Voltage Options: 1.25V, 2.048V, 2.5V, 3V, 3.3V, 4.
PAGE 2
LT1790 W W W AXI U U ABSOLUTE RATI GS (Note 1) Input Voltage .......................................................... 20V Specified Temperature Range Commercial ............................................ 0°C to 70°C Industrial ............................................ – 40°C to 85°C Output Short-Circuit Duration ......................... Indefinite Operating Temperature Range (Note 2) ........................................... – 40°C to 125°C Storage Temperature Range (Note 3) .............
PAGE 3
LT1790 1.25V ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the specified temperature range, otherwise specifications are at TA = 25°C. CL = 1µF and VIN = 2.6V, unless otherwise noted. PARAMETER CONDITIONS Output Voltage (Notes 3, 4) Output Voltage Temperature Coefficient (Note 5) Line Regulation MIN TYP MAX LT1790A 1.24937 –0.05 1.250 1.25062 0.05 V % LT1790B 1.24875 –0.10 1.250 1.25125 0.10 V % LT1790AC ● ● 1.24850 –0.120 1.250 1.25150 0.
PAGE 4
LT1790 2.048V ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the specified temperature range, otherwise specifications are at TA = 25°C. CL = 1µF and VIN = 2.8V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX Output Voltage (Notes 3, 4) LT1790A 2.04697 –0.05 2.048 2.04902 0.05 V % LT1790B 2.04595 –0.10 2.048 2.05005 0.10 V % Output Voltage Temperature Coefficient (Note 5) Line Regulation LT1790AC ● ● 2.04554 –0.120 2.048 2.05046 0.
PAGE 5
LT1790 2.5V ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the specified temperature range, otherwise specifications are at TA = 25°C. CL = 1µF and VIN = 3V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX Output Voltage (Notes 3, 4) LT1790A 2.49875 –0.05 2.5 2.50125 0.05 V % LT1790B 2.4975 –0.10 2.5 2.5025 0.10 V % Output Voltage Temperature Coefficient (Note 5) Line Regulation LT1790AC ● ● 2.4970 –0.120 2.5 2.5030 0.120 V % LT1790AI ● ● 2.
PAGE 6
LT1790 3V ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the specified temperature range, otherwise specifications are at TA = 25°C. CL = 1µF and VIN = 3.5V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX Output Voltage (Notes 3, 4) LT1790A 2.9985 –0.05 3 3.0015 0.05 V % LT1790B 2.9970 –0.10 3 3.003 0.10 V % Output Voltage Temperature Coefficient (Note 5) Line Regulation LT1790AC ● ● 2.99640 –0.120 3 3.00360 0.120 V % LT1790AI ● ● 2.99475 –0.
PAGE 7
LT1790 3.3V ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the specified temperature range, otherwise specifications are at TA = 25°C. CL = 1µF and VIN = 3.8V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX 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 % Output Voltage Temperature Coefficient (Note 5) Line Regulation LT1790AC ● ● 3.29604 –0.120 3.3 3.30396 0.120 V % LT1790AI ● ● 3.
PAGE 8
LT1790 4.096V ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the specified temperature range, otherwise specifications 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 % Output Voltage Temperature Coefficient (Note 5) Line Regulation LT1790AC ● ● 4.09108 –0.120 4.096 4.10092 0.
PAGE 9
LT1790 5V ELECTRICAL CHARACTERISTICS The ● denotes specifications that apply over the specified temperature range, otherwise specifications are at TA = 25°C. CL = 1µF and VIN = 5.5V, unless otherwise noted. PARAMETER CONDITIONS Output Voltage (Notes 3, 4) Output Voltage Temperature Coefficient (Note 5) Line Regulation MIN TYP MAX LT1790A 4.9975 –0.05 5 5.0025 0.05 V % LT1790B 4.995 –0.10 5 5.005 0.10 V % LT1790AC ● ● 4.99400 –0.120 5 5.00600 0.120 V % LT1790AI ● ● 4.99125 –0.
PAGE 10
LT1790 ELECTRICAL CHARACTERISTICS 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 Applications Information. 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.
PAGE 11
LT1790 U W 1.25V TYPICAL PERFOR A CE 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. Power Supply Rejection Ratio vs Frequency Line Regulation 500 –10 100 TA = 125°C 1.270 1.265 1.260 1.255 TA = 25°C 1.250 TA = –55°C 1.245 1.240 1.235 1.230 1.225 4 2 0 –20 –30 –40 –50 –60 –70 1k 10k 100k FREQUENCY (Hz) 0.30 0.20 0.15 6 2 80 VOUT RL 5k 1M LT1790S6-1.
PAGE 12
LT1790 U W 2.048V TYPICAL PERFOR A CE 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. Minimum Input-Output Voltage Differential (Sourcing) Output Voltage Temperature Drift 2.056 130 10 TA = 25°C OUTPUT CURRENT (mA) 2.054 2.052 2.050 2.048 2.
PAGE 13
LT1790 U W 2.048V TYPICAL PERFOR A CE 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. – 2.048V Characteristics Long-Term Drift 0.30 100 TA = 30°C 80 2 TYPICAL PARTS SOLDERED TO PCB R1 10k 3V 4 0.25 LT1790-2.048 CURRENT IN RL (mA) 1 0.20 40 VOUT RL 5k 1µF 20 ppm 0.15 60 6 2 –VEE 0 –20 0.10 TA = 125°C TA = 25°C TA = –55°C 0.05 –40 –60 –80 0 –4 –3.
PAGE 14
LT1790 U W 2.5V TYPICAL PERFOR A CE 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. Minimum Input-Output Voltage Differential (Sourcing) Output Voltage Temperature Drift 2.508 Minimum Input-Output Voltage Differential (Sinking) 90 10 FOUR TYPICAL PARTS 2.504 2.502 2.500 2.498 TA = –55°C VOLTAGE DIFFERENTIAL (mV) OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 2.
PAGE 15
LT1790 U W 2.5V TYPICAL PERFOR A CE 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. Long-Term Drift (Data Points Reduced After 500 Hr) – 2.5V Characteristics 140 0.30 TA = 30°C 120 2 TYPICAL PARTS SOLDERED TO PCB R1 10k 3V 4 LT1790-2.5 100 6 1, 2 0.20 1µF 60 ppm 0.15 80 VOUT RL 5k –VEE 40 20 0.10 0 TA = 25°C TA = 125°C TA = –55°C 0.05 –20 –40 0 –4.0 –3.
PAGE 16
LT1790 U W 5V TYPICAL PERFOR A CE 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. Minimum Input-Output Voltage Differential (Sourcing) Output Voltage Temperature Drift 5.025 Minimum Input-Output Voltage Differential (Sinking) 90 10 FOUR TYPICAL PARTS 5.015 5.010 5.005 5.000 4.995 VOLTAGE DIFFERENTIAL (mV) 70 OUTPUT CURRENT (mA) OUTPUT VOLTAGE (V) 5.
PAGE 17
LT1790 U W 5V TYPICAL PERFOR A CE 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. – 5V Characteristics Long-Term Drift 0.30 100 TA = 30°C 80 2 TYPICAL PARTS SOLDERED TO PCB R1 10k 5.5V 4 0.25 LT1790-5 CURRENT IN RL (mA) 1 0.20 40 VOUT RL 5k 1µF 20 ppm 0.15 60 6 2 –VEE 0 –20 0.10 –40 TA = 125°C TA = 25°C 0.
PAGE 18
LT1790 U U W U 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 capacitor affects the turn-on and settling time for the output to reach its final value.
PAGE 19
LT1790 U W U U APPLICATIONS INFORMATION stability during load transients. This connection maintains nearly the same accuracy and temperature coefficient of the positive connected LT1790. VGEN 8V 6V Long-Term Drift VOUT (AC Coupled) 4V 2V 0V 1790 F06 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.
PAGE 20
LT1790 U W U U APPLICATIONS INFORMATION 16 8 14 7 0°C TO 25°C 12 NUMBER OF UNITS NUMBER OF UNITS 6 5 70°C TO 25°C 4 3 10 4 1 2 0 –80 –70 –60 –50 –40 –30 –20 –10 0 DISTRIBUTION (ppm) 10 20 30 40 50 –240 –200 –160 –120 –80 –40 DISTRIBUTION (ppm) 0 40 80 1790 F09 1790 F08 Figure 8. Worst-Case 0°C to 70°C Hysteresis on 30 Units –40°C TO 25°C 6 2 0 85°C TO 25°C 8 Figure 9. Worst-Case –40°C to 85°C Hysteresis on 30 Units the transition region.
PAGE 21
LT1790 U U W U APPLICATIONS INFORMATION R1 330k VS 6V TO 160V R2 4.7k ON SEMI MMBT5551 BZX84C12 C1 0.1µF R1 330k ON SEMI MMBT5551 LT1790 VOUT C1 0.1µF VS 6.5V TO 160V BAV99 C2 1µF VOUT LT1790 C2 1µF 1790 F11 1790 F12 Figure 11. Extended Supply Range Reference VS 2.8V TO 3.3V NO LOAD SUPPLY CURRENT 120µA R1 680Ω 5% R3 22Ω 5% Figure 12. Extended Supply Range Reference R4 1k 5% + LT1782 – R2 100k 5% VISHAY SILICONIX Si3445DV C1 0.1µF LT1790-2.5 C2 1µF 17909 F13 VOUT = 2.
PAGE 22
LT1790 W W SI PLIFIED SCHE ATIC 4 VIN 6 VOUT 1, 2 GND 1790 SS 1790fa 22
PAGE 23
LT1790 U PACKAGE DESCRIPTIO S6 Package 6-Lead Plastic SOT-23 (Reference LTC DWG # 05-08-1636) 2.80 – 3.10 (.110 – .118) (NOTE 3) SOT-23 (Original) SOT-23 (ThinSOT) A .90 – 1.45 (.035 – .057) 1.00 MAX (.039 MAX) A1 .00 – 0.15 (.00 – .006) .01 – .10 (.0004 – .004) A2 .90 – 1.30 (.035 – .051) .80 – .90 (.031 – .035) L .35 – .55 (.014 – .021) .30 – .50 REF (.012 – .019 REF) 2.60 – 3.00 (.102 – .118) 1.50 – 1.75 (.059 – .069) (NOTE 3) PIN ONE ID .95 (.037) REF .25 – .50 (.010 – .
PAGE 24
LT1790 U TYPICAL APPLICATIO – 2.5V Negative 50mA Series Reference No Load Supply Current ICC = 1.6mA IEE = 440µA VCC = 5V 2k 4 VZ = 5.1V LT1790-2.5 6 1, 2 5.1k –2.5V 50mA VEE = –5V MPS2907A 1µF 1790 TA03 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1019 Precision Reference Low Noise Bandgap, 0.05%, 5ppm/°C LTC 1798 Micropower Low Dropout Reference 0.15% Max, 6.