The Raspberry Pi is connected with the ADS1262 by the GPIO pins. They deliver 5V, 3.3V, GND, MISO (SPI), MOSI (SPI), SCLK (SPI), CS (SPI) and interrupt (DRDY) signals.
For the connection between the SM-24 and the ADS1262 the 1 kΩ termination shunt is split into two 470 Ω resistors in series, a capacitor is set in parallel to the outlet of the SM24 in order to suppress high frequency noise, and REFOUT (2.5 V) is connected to the middle of two 470 Ω resistors.
The two 470 Ω resistors in the middle are calibration resistors according to its data sheet in order to flatten the response curve. The other two 1kΩ resistors, leading to the ADS1262, are for current limiting, in case that the output voltage is larger than the maximum input voltage of the ADC.
Even if the output voltage is 10 V, which is much higher than the usual output of several mV, the current would be limited to 5 mA, which doesn’t destroy the electrostatic discharge diodes (ESD) of the ADS1262 analog inputs.
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