Because PROT is an open-drain line with an internal pull-up, you can tie multiple PROT pins together (from multiple LX1692s or other fault-monitoring ICs). If any device pulls the line low, all devices latch off.
Additionally, an external microcontroller or supervisor can pull PROT low to force a shutdown. This is useful for:
Example Circuit:
PROT pin (LX1692) ---+--- To other LX1692 PROT pins
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+--- 10kΩ pull-up to 5V (optional if internal current source is sufficient)
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+--- Drain of external N-MOSFET (source to GND)
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Gate of N-MOSFET from microcontroller (active high shutdown command)
Caution: Do not pull PROT high externally (e.g., connect to 5V directly). This can conflict with the internal pull-down and damage the pin or prevent proper fault detection.
Internally, the PROT pin is connected to: lx1692 protection pin
Normal Operation: The pin is pulled high (≈5V) by the internal current source. Fault Condition: The IC turns on the internal open-drain transistor, grounding the PROT pin (≈0V). Latch: Once the PROT pin is pulled low (by internal or external means), the IC latches off all PWM outputs. The only way to restart is to cycle the ( V_CC ) power (power-on reset).
Understanding what should trigger the pin helps you know when not to bypass it. Because PROT is an open-drain line with an
A: You can, but it is unsafe. It should only be done as a temporary test or on a device you are willing to risk destroying. For a permanent fix, replace the faulty component causing the trigger.