Dear STMicroelectronics Support Team,
We are currently using the STEF12S eFuse in a 12 V power distribution design and would like clarification on the correct usage of the EN/FAULT shared pin, specifically from a microcontroller software perspective.
Application Context
Nominal input voltage: 12 V
Load current: up to 5 A
MCU-controlled power path
Requirement to detect output short-to-GND, overcurrent, and thermal faults in firmware
Understanding So Far
From the datasheet and functional diagrams, we understand that:
The EN/FAULT pin serves as an enable input during normal operation.
The same pin is pulled LOW by the device (open-drain) to indicate fault conditions such as overcurrent, short-circuit, or thermal shutdown.
During thermal shutdown, the pin voltage may be at an intermediate level due to internal pull-up and pull-down circuitry.
The output is disabled during fault conditions.
Clarifications Requested
Is the recommended firmware approach to treat any LOW or non-HIGH level on EN/FAULT as a fault condition, regardless of the exact voltage level?
During a fault condition, should the MCU:
What is the recommended sequence and timing for clearing a fault and re-enabling the device using the EN/FAULT pin?
Are there any reference designs, application notes, or example firmware flow diagrams that demonstrate correct MCU handling of the EN/FAULT pin?
Is an external pull-up resistor on the EN/FAULT pin recommended when interfacing with an MCU GPIO, or is the internal pull-up sufficient for reliable operation?
Our primary goal is to ensure robust and unambiguous fault detection in firmware when the output is shorted to ground, while avoiding contention on the shared EN/FAULT pin.
