The body control module (BCM) is an electronic control unit responsible for monitoring and controlling various electronic accessories in a vehicle's body. Detection of various mechanical switches status in a vehicle is one important task handled by the BCM. Besides the typical on-and-off (or digital) type of switch, more sophisticated type of switches, called resistor-coded switches, can also be present in an automotive body control system.

Resistor-coded switches have more than 2 unique switch states, and are often used for implementation of wiper, illumination, and signal control arms in a vehicle. Due to various voltage potentials generated by different positions of a resistor-coded switch, an ADC, typically inside the microcontroller, is used to detect the different states of the switch. The TIC12400-Q1 can natively support monitoring of a resistor-coded switch with its integrated 10-bit ADC and configurable thresholds. The following application diagram depicts how the TIC12400-Q1 is used in a BCM to detect external mechanical resistor-coded switches and a detailed design example is shown in the following sections.

Figure 9-5 Using TIC12400-Q1 to Monitor a Resistor-Coded Switch in Body Control Module Application