Mp3378e Protection Pin Upd Better Page

PROT pin oscillated at 1.0V–1.3V at 2Hz. VOUT pulsed to 42V (target 48V), then dropped to 0V. No channel current.

The OVP lower resistor (10kΩ) had a hairline crack, measuring 10.8kΩ. Recalculated V_PROT: Target 1.25V, actual 1.17V (due to 8% increase). This 0.08V difference fell into UPD zone. mp3378e protection pin upd

Introduction In the world of modern display technology—from ultra-thin laptops and automotive infotainment systems to high-brightness industrial monitors—the MP3378E from Monolithic Power Systems (MPS) has emerged as a go-to solution for driving LED backlight strings. This 8-channel, boost-controlled LED driver is celebrated for its high efficiency, dimming accuracy, and built-in fault management. PROT pin oscillated at 1

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. The OVP lower resistor (10kΩ) had a hairline