Texas Instruments ADS1263EVM-PDK User Manual page 12

Analog Interface
3.1.2.4.2 Connecting a 3-Wire RTD
Connect the two measurement leads of a 3-wire RTD to any of the following differential pairs on terminal block
J3: AIN0 and AIN1, AIN2 and AIN3, or AIN6 and AIN7. Connect the remaining common lead to AIN4.
shows an example where the 3-wire RTD is connected to differential pair AIN6 and AIN7. Two IDACs are used in
this example, though this approach is not strictly necessary.
J3
External
Jumper
3-wire
RTD
J4
J5
External
Jumper
In this configuration, connect external jumper wires between AIN7 (J3:8) to AINCOM (J5:1). An additional jumper
wire is required between AIN6 (J3:7) to AIN3 (J3:4) if two IDACs are used. These jumper wires route the IDAC
currents on AINCOM and AIN3 around the input filtering to prevent voltage drops in the input signal path.
IDAC1 current flows across the RTD and then the combined current of IDAC1 and IDAC2 flows through R1. The
ratiometric reference voltage is generated between AIN4 and AIN5. The IDAC currents are then routed to GND
through resistor R2 when populated.
12 ADS1263EVM-PDK Evaluation Module
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
AIN8
AIN9
R1
AINCOM
REFOUT
Figure 3-8. 3-Wire RTD Ratiometric Connection Example
Copyright © 2023 Texas Instruments Incorporated
ADS1263EVM
AVDD
AINCOM
AIN7
AIN6
AIN3
Mux
AIN4
AIN5
R2
SBAU206B – APRIL 2015 – REVISED MAY 2023
www.ti.com
Figure 3-8
ADS1263
IDAC1
PGA ADC
IDAC2
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