Analog inputs to the EVM can be connected to either the terminal blocks or to the header pins associated with each ADC channel. The headers for each channel allow the user to configure the inputs differentially depending on the signal to be measured. The screw terminal blocks can interface directly with the leads of an external sensor input. Figure 2-1 shows the signal chain used for all three input channels on the EVM .

Figure 2-1 Analog Input (Schematic)

There are 3 analog input channels for the AMC131M03EVM: channel 0, 1, and 2. Signals can be applied to these channels via terminal blocks J3, J2, and J1, respectively.

Channel 0 (AIN0) and Channel 1 (AIN1) contain the same circuitry. This includes a terminal block to apply signals to AIN0P/N and AIN1P/N. These inputs can also be shorted to HGND via the provided jumpers on JP2 and JP3, respectively. Each channel also contains both common-mode and differential passive filters for antialiasing. If needed, one input on each channel can be divided down using the provided resistor divider footprints (this is unpopulated by default).

Channel 2 (AIN2) shares a negative channel input with Channel 1 (AIN12N). An external voltage can be applied to AIN2P by connecting to the terminal block, J1. This signal measured against AIN12N by configuring JP1 in the [1-2] position.

Another common use of Channel 2 is to measure the output of an external temperature sensor. The AMC131M03EVM provides an example temperature sensor circuit using the TMP6331, a 100-kΩ linear thermistor. The temperature sensor output can be selected using the [2-3] position on JP1.