UCC5870-Q1 designates three AIx inputs (AI1, AI3, AI5) to support thermal diode sensing for up to three power transistors sharing the same ground reference. An example with a single thermal diode measurement is shown in Figure 3-28. The temperature protection is intended for power transistors with integrated temperature sensing diodes in order to monitor the junction temperature, which can be an indication for the controller to discontinue to operate the inverter or as a mode of failure. The AIx input provides a current that biases the integrated diode, and the voltage is monitored at the AIx input. The bias current can be enabled via SPI on one or all of the available AI pins. The temperature measurement is fed back into the ADC Data register, and a fault can also be configured for thermal shutdown (TSD) or thermal warning (TWN). The fault must exist for the deglitch time programmed before the fault is registered. The AIx pins can be enabled/disabled for temperature monitoring.

Figure 3-28 Power switch temperature monitoring