Datasheet LT1031, LH0070 (Analog Devices) - 6
| Manufacturer | Analog Devices |
| Description | Precision 10Volts Reference |
| Pages / Page | 12 / 6 — TYPICAL PERFOR A CE CHARACTERISTICS. Output Noise 0.1Hz to 10Hz. … |
| File Format / Size | PDF / 165 Kb |
| Document Language | English |
TYPICAL PERFOR A CE CHARACTERISTICS. Output Noise 0.1Hz to 10Hz. APPLICATIO S I FOR ATIO. Trimming Output Voltage
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Text Version of Document
LT1031/LH0070
W U TYPICAL PERFOR A CE CHARACTERISTICS Output Noise 0.1Hz to 10Hz
FILTERING = 1 ZERO AT 0.1Hz 2 POLES AT 10Hz µV/DIV) 10µV (1ppm) OUTPUT VOLTAGE NOISE (10 0 1 2 3 4 5 6 TIME (MINUTES) LT1031 • TPC16
U U W U APPLICATIO S I FOR ATIO Trimming Output Voltage Effect of Reference Drift on System Accuracy
The LT1031 output can be trimmed by driving the ground A large portion of the temperature drift error budget in pin. The suggested method is shown in the illustration many systems is the system reference voltage. The graph below. A 5Ω resistor is inserted in series with the ground below indicates the maximum temperature coefficient pin. The top of the resistor is supplied current from a trim allowable if the reference is to contribute no more than potentiometer. This technique requires fairly high trim 1/2LSB error to the overall system performance. The current of up to 1.5mA from the LT1031 or 3.5mA from the example shown is a 12-bit system designed to operate –15V supply; however it is necessary to maintain low drift over a temperature range from 25°C to 65°C
.
Assuming in the reference. Ground pin current changes in the LT1031, the system calibration is performed at 25°C, the with temperature, could be as high as 4µA/°C.
This, temperature span is 40°C. The graph shows that the coupled with the 5Ω external resistor, creates up temperature coefficient of the reference must be no worse to 2ppm/°C drift in the reference (5Ω • 4µA/°C = 20µV/°C than 3ppm/°C if it is to contribute less than 1/2LSB error. = 2ppm/°C). If induced drift higher than this can be For this reason, the LT1031 has been optimized for low tolerated, all resistor values in the trim circuit can be raised drift. proportionately to reduce current drain.
Maximum Allowable Reference Drift Output Voltage Trimming
100 8-BIT LT1031 °C) VIN IN OUT VOUT GND 10-BIT 10 R2* 4.3k R3 50k 12-BIT R1** 1/2LSB ERROR (ppm/ 5Ω 14-BIT –15V MAXIMUM TEMPERATURE COEFFICIENT FOR 1.0 *CAN BE INCREASED TO 5.6k FOR 10 20 30 40 50 60 70 80 90 100 LT1031B AND LH0070-2 TEMPERATURE SPAN (°C) **INCREASE TO 10Ω FOR LT1031D LT1031 • TA04 LT1031 • TA03 1031fb 6
W U TYPICAL PERFOR A CE CHARACTERISTICS Output Noise 0.1Hz to 10Hz
FILTERING = 1 ZERO AT 0.1Hz 2 POLES AT 10Hz µV/DIV) 10µV (1ppm) OUTPUT VOLTAGE NOISE (10 0 1 2 3 4 5 6 TIME (MINUTES) LT1031 • TPC16
U U W U APPLICATIO S I FOR ATIO Trimming Output Voltage Effect of Reference Drift on System Accuracy
The LT1031 output can be trimmed by driving the ground A large portion of the temperature drift error budget in pin. The suggested method is shown in the illustration many systems is the system reference voltage. The graph below. A 5Ω resistor is inserted in series with the ground below indicates the maximum temperature coefficient pin. The top of the resistor is supplied current from a trim allowable if the reference is to contribute no more than potentiometer. This technique requires fairly high trim 1/2LSB error to the overall system performance. The current of up to 1.5mA from the LT1031 or 3.5mA from the example shown is a 12-bit system designed to operate –15V supply; however it is necessary to maintain low drift over a temperature range from 25°C to 65°C
.
Assuming in the reference. Ground pin current changes in the LT1031, the system calibration is performed at 25°C, the with temperature, could be as high as 4µA/°C.
This, temperature span is 40°C. The graph shows that the coupled with the 5Ω external resistor, creates up temperature coefficient of the reference must be no worse to 2ppm/°C drift in the reference (5Ω • 4µA/°C = 20µV/°C than 3ppm/°C if it is to contribute less than 1/2LSB error. = 2ppm/°C). If induced drift higher than this can be For this reason, the LT1031 has been optimized for low tolerated, all resistor values in the trim circuit can be raised drift. proportionately to reduce current drain.
Maximum Allowable Reference Drift Output Voltage Trimming
100 8-BIT LT1031 °C) VIN IN OUT VOUT GND 10-BIT 10 R2* 4.3k R3 50k 12-BIT R1** 1/2LSB ERROR (ppm/ 5Ω 14-BIT –15V MAXIMUM TEMPERATURE COEFFICIENT FOR 1.0 *CAN BE INCREASED TO 5.6k FOR 10 20 30 40 50 60 70 80 90 100 LT1031B AND LH0070-2 TEMPERATURE SPAN (°C) **INCREASE TO 10Ω FOR LT1031D LT1031 • TA04 LT1031 • TA03 1031fb 6
