AMP-04 0 to 400℃ temperature measurement circuit

The AMP-04 is a high-resolution operational amplifier powered by a single power supply and with single resistor gain adjustment. The input voltage drift is less than 150 pLV, the current drift is less
than 5nA, the temperature drift is 8 pA/aC, and the gain nonlinearity is 0.005%. AMP-04
0. 400qC temperature measurement circuit is shown in Figure 1-13. The temperature measurement range of this circuit is 0-4000C, and the measurement accuracy is ±0.5℃.
    Ri - R3, RPi, and RTD form a bridge
temperature detection circuit, RP, to adjust the bridge balance;
IC2 and IC3 are constant current and constant voltage sources, 1C3 outputs
a 2.500V precision reference voltage, which is
adjusted by Rs, R6, and RP2 to make IC2 . (+) terminal potential is
0. 202V, IC2. A constant current is output and added to
the bridge. The output of the temperature measurement bridge is directly sent to
Icl for amplification. Pin ① is connected to an external resistor to adjust the gain
, and RP4 is used to fine-tune the gain. When the temperature changes from 0 to
4000C, the output voltage is O—4. OV .
    When debugging, first use a 100. 00Q resistor
(equivalent to 0℃) instead of RTD, adjust
RPi so that the output voltage is 0.oOv; then
use 247. 04 (equivalent to 400C) and 175. 84n resistors (equivalent to (at 200C) instead of RTD, adjust RP4 and
RP3 respectively so that the output voltages are 4.00 and 2.0 OV respectively .