To have full coverage for a potential overtemperature event, the TPS544C26 device implements three overtemperature protection circuitries - two on the Controller die and one on the Power Stage (PS) die.

Programmable OTP by Monitoring the Controller Die Temperature

The on-die temperature sense circuit senses the controller die temperature. The sensed signal is fed into an internal ADC and converted to the Controller die temperature which is reported as (8Dh) READ_TEMPERATURE_1 through the Telemetry sub-system. This feature utilizes a digital comparator that compares the output of the IC TEMPERATURE telemetry to the fault threshold selected in (4Fh) OT_FAULT_LIMIT register. The device stops the SW switching when the sensed IC temperature goes beyond the selected threshold. The device response to a Programmable OTP event is described in (50h) OT_FAULT_RESPONSE.

Analog OTP by Monitoring the Controller Die Temperature

The sensed temperature signal is fed into an analog OTP circuit on the Controller die as well. An analog comparator is utilized to compare the output of the Controller die temperature sensing circuit to a fixed threshold (rising 166 °C typical). The device stops the SW switching when the sensed IC temperature goes beyond the fixed threshold. The device response to an Analog OTP event is always the same as the Programmable OTP.

Given the fixed threshold (166 °C typical) for the Analog OTP is higher than the highest setting (150 °C typical) in Programmable OTP, the Analog OTP is unlikely to trigger during the nominal operation.

Analog OTP by Monitoring the Power Stage Die Temperature

A temperature sensing circuit is implemented in the Power Stage (PS) die. This sensed is fed into an analog OTP circuit on the PS die. An analog comparator is utilized to compare the output of the PS die temperature sensing circuit to a fixed threshold (rising 166 °C typical). The device stops the SW switching when the sensed IC temperature goes beyond the fixed threshold. Once the PS die temperature falls 30 °C below the rising threshold, the device automatically restarts with an initiated soft-start. This Analog OTP is a non-latch protection.