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3.5.3.8 Connecting a 4-Wire RTD Using a High-Side R
REF
to J6 on the ADS1x48EVM
Figure 3-20 shows how to connect a 4-wire RTD using a high-side R
REF
configuration to J6.
REFP1
REFN1
AIN0
REFP1
REFN1
R
T
D
RTD_A
RTD_B
RTD_C
IEXC1
AIN3
AIN2
JP3
JP4
JP5
IEXC2 IEXC2
AIN1
IDA C
JP6
Figure 3-20. Connection Diagram for a 4-Wire RTD Using a High-Side R
REF
Figure 3-20 also shows that for this RTD configuration, the RTD is connected to REFN1, RTD_A, RTD_B, and
RTD_C. Additionally, jumpers JP5 and JP6 are connected whereas jumpers JP3 and JP4 are disconnected.
Finally, the AIN1 pin on the ADS1x48 is configured to be a current source and the measurement is taken
between AIN2 and AIN3.
Table 3-5 summarizes the necessary connections and ADC configuration settings.
3.5.3.9 Summary of ADS1x48EVM RTD Configuration Settings
Table 3-5 summarizes the required IDAC, jumper, and analog input channel settings to measure each RTD
configuration using the ADS1x48EVM.
Table 3-5. ADS1x48EVM Settings for Different RTD Types
RTD No. of IDACs R
REF
IDAC Channels JP3 JP4 JP5 JP6 AINP AINN
2-wire
1 Low-side IEXC1 On On Off Off AIN3 AIN1
1 High-side AIN1 Off On On On AIN0 AIN3
3-wire
1 Low-side IEXC1 On On Off Off
AIN3
(1)
AIN2
(1)
AIN2
(2)
AIN1
(2)
1 High-side AIN1 Off On On On
AIN0
(1)
AIN2
(1)
AIN2
(2)
AIN3
(2)
2 Low-side IEXC1, IEXC2 On On Off Off AIN3 AIN2
2 High-side AIN1, IEXC2 Off On On On AIN0 AIN2
4-wire
1 Low-side IEXC1 On Off Off Off AIN3 AIN2
1 High-side AIN1 Off Off On On AIN2 AIN3
(1) First measurement.
(2) Second measurement.
ADS1x48EVM Overview www.ti.com
26 ADS1x48EVM Evaluation Module SBAU378A – SEPTEMBER 2021 – REVISED JANUARY 2022
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