The OVP pin (Pin 10 in the TSSOP-28 EP package) monitors the boost output voltage through an external resistor divider. It performs several safety-critical tasks:
Sets the current for each LED string via an external resistor.
Enters Hiccup Mode to limit power dissipation during direct electrical shorts. Internal Die Sensor mp3378e protection pin upd
: Detects severe faults in the power path (e.g., a shorted boost diode) and immediately halts operation.
The MP3378E includes comprehensive protection mechanisms that monitor various conditions to prevent hardware failure: LED Protection : Detects and responds to both The OVP pin (Pin 10 in the TSSOP-28
Bypassing protection pins on WLED controllers like the MP3378E from MPS can lead to overheating, burnt LED strips, or permanent damage to the IC.
In the refined architecture, the protection pin (often tied to the or Over-Voltage/Open-LED Protection circuitry) has been updated to handle nuanced failure modes. The evolution moves away from a simple voltage threshold trigger. Instead, the update introduces a smart-polling or latch-off logic that differentiates between transient noise and genuine hardware failure. Internal Die Sensor : Detects severe faults in
The IC monitors the OVP pin voltage against an internal reference. To prevent the chip from sensing an over-voltage state when an LED string is weak or disconnected:
The stabilizes the voltage feedback loop. It connects to an external RC (resistor-capacitor) network. During a soft-start or severe load variance, if the voltage on COMP stays railed at its maximum threshold for too long, the internal fault logic flags an overload or loop error and shuts down the gate drive. ISET / LED1 to LED4 Channels
To update the IC state and bypass the protection loop for debugging, technicians frequently ground the fault detection nodes or modify the OVP resistor network. By forcing a stable reference voltage onto the protection-checking pins, the internal fault amplifier is bypassed, allowing the backlight inverter to remain on continuously. This step lets you visually isolate which exact LED strip contains dead or dim diodes before installing replacement parts.
| Pin | Protection type | Interaction with PRO/UPD | |-----|----------------|---------------------------| | OVP | Over-voltage protection | Auto-restart or latch based on PRO | | ISET | Over-current protection | Same fault response logic | | VCC UVLO | Input under-voltage | Can be bypassed only if UPD enabled | | TS | Thermal shutdown | Always auto-recover (not affected by PRO) |