A universal analog input module can accept either an analog voltage or a current input. This enables real-time analog input configurability and unified hardware development for different analog input conditions. Multiple measurement modes supported in an RTD 4-wire scenario can be internally switched using ISOMOS. Each path is individually controllable using GPIO signal from MCU, or using a GPIO expander to reduce the number of control signals needed for exclusive configurability for multi-channel designs. Figure 2-3 illustrates the architecture for a channel to channel isolated analog input module using ISOM8610.

In the proposed architecture, each differential pair gets sampled serially. Each input pair can be sampled individually by setting the control signals for the corresponding ISOMOS pair to High. During this time, the control signals for the rest of the pairs are set to Low. ISOM8610 supports blocking voltage of up to 70V without a secondary side isolated high voltage supply to enable robust channel-to-channel isolated designs.

For voltage inputs, ISOM8610 on state resistance of 7Ω (typ.) comes in series with the input impedance of the measuring ADC, with input impedance generally >100MΩ, minimally impacting the measurement accuracy. Once the digitization for the pair is complete, the switch pair is turned off, and the next pair is turned on. ISOM8610 offers best in class switching performance of turn-on and turn-off time of < 200μs, enabling faster switching. ISOM8610 offers galvanic isolation across the barrier, which protects the sensitive circuitry like the MCU from the noisy field side.