SBOS487B June 2009 – March 2020 PGA280
Figure 44 shows the arrangement of the input switches. They are controlled individually via the digital SPI. The switches B1b, B2b, A1b, and A2b are controlled automatically with the buffer (BUF) operation.
Switches A and B select the signal input. Input 1 (INP1 and INN1) provides two current sources and two switches that connect to VSON (which is typically the analog ground). This configuration is intended for wire break diagnosis. D12 can discharge an external capacitor or generate a starting condition.
Switches C1 and C2 are used to measure the input voltage referred to GND (VSON); for example, with A1 and C2 closed. This scheme measures the voltage signal connected to the input pin (INP1) referred to a common ground. The BUF output is protected against a short to VSON. See the section for more information about switch control.