To have full coverage for a potential overtemperature event, the TPS548C26 device implements two overtemperature protection circuitries - one on the Controller side and one on the Power Stage (PS) side.

OTP by Monitoring the Power Stage Temperature

A temperature sensing circuit is implemented in the Power Stage (PS) side. This sensed temperature is fed into an OTP circuit on the PS side to be compared with a fixed threshold (rising 166°C typical). The device stops the SW switching when the sensed IC temperature goes beyond the fixed threshold. After the PS die temperature falls 30°C below the rising threshold, the device automatically restarts with an initiated soft-start. This OTP on power stage side is a non-latch protection.

OTP by Monitoring the Controller Temperature

The Controller features an internal on-die temperature sensing circuit. The sensed temperature signal is fed into an OTP comparator on the Controller side and compared with a fixed threshold (rising 166°C typical). The device stops the SW switching when the sensed Controller temperature goes beyond the fixed threshold. The device response to an OTP event is set by the SS pin strap detection. With the Latch-off response selected, the device latches OFF both high-side and low-side FETs. The latch is cleared with a reset of VCC or by toggling the EN pin. With the Hiccup response selected, the device enters hiccup mode and re-starts automatically after a hiccup sleep time of 56 ms, without limitation on the number of restart attempts.

Given the power loss on the controller side is much less than the power loss on the power stage side, the OTP on controller side is unlikely to trigger during the nominal operation.