The MP3378 triggers the Over-Voltage Protection when the voltage at the OVP pin exceeds the internal reference threshold (typically around 1.20V to 1.25V , depending on the exact revision/supplier).
: If an LED string shorts, the voltage on the corresponding LEDx pin rises. The IC detects this abnormal voltage and shuts down the affected string to prevent overheating. 4. System-Level Protections mp3378e protection pin upd
26 May 2017 — * MP3378E. * WLED Controller: * Buck Converter: * WLED Controller. VIN1 .............................................. - 0.3V to + Mouser Electronics MP3378E - Monolithic Power Systems The MP3378 triggers the Over-Voltage Protection when the
The MP3378E doesn't have a single "protection pin." Instead, it uses a network of monitoring pins to trigger a shutdown if any safety threshold is exceeded. Understanding these pins is the key to diagnosing a backlight that flashes then dies. MP3378E - Monolithic Power Systems MP3378E - Monolithic Power Systems However
However, one of the most misunderstood and critical aspects of the MP3378E is its behavior, particularly a phenomenon documented in advanced application notes as UPD (Under-Protection Detection). For engineers troubleshooting “no backlight” conditions, erratic blinking, or immediate shutdown after startup, understanding the MP3378E protection pin UPD mechanism is not just academic—it’s the key to a successful board repair or design.
| Symptom | Likely cause | Fix | |---------|--------------|-----| | Driver latches off permanently | PRO low + fault occurred | Cycle VCC or pull PRO high | | Driver keeps restarting every ~1s | PRO high + intermittent fault | Check LEDs, OVP resistor, or set PRO low | | Boost works only above 4.5V | UVLO enabled, no UPD | Enable UPD if low-VIN needed, else raise input | | No start-up at low VIN with UPD enabled | Input current limit tripped | Reduce load or add soft-start |