To set the maximum allowable output voltage, select the upper ($R_OVP_UP$) and lower ($R_OVP_LOW$) divider resistors using the formula: $$V_OUT_MAX = V_OVP_TH \times \left(1 + \fracR_OVP_UPR_OVP_LOW\right)$$
If one string is faulty, grounding that specific LED channel pin through a resistor can sometimes trick the IC into ignoring that string's fault. Technical Specifications
: Monitors the boosted output voltage using a resistor divider network. If an LED string opens, the boost converter pumps up the voltage trying to maintain current; once the OVP pin exceeds its reference threshold (typically 1.2V to 1.25V internally), protection triggers.
The MP3378E features extensive protection to prevent catastrophic failure of the backlight system, including: mp3378e protection pin upd
For electronics technicians and engineers dealing with backlight failures, understanding the MP3378E protection mechanism—particularly how to diagnose, test, or sometimes temporarily bypass the protection pins—is critical. 1. Overview of MP3378E Protection Features
| 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 |
Check the voltage at the OVP pin (resistor divider from Boost output to Ground). 3. Check for False Triggers To set the maximum allowable output voltage, select
A critical safeguard that detects failures in the main power stage components, immediately shutting down to prevent catastrophic board damage. Buck Converter Protections:
If all strings are open (e.g., the display connector is unplugged), the boost converter will ramp up voltage rapidly. The OVP pin triggers immediately to shut down the converter, preventing voltage explosion.
: The OVP pin monitors the output voltage of the step-up converter via a resistor divider. the display connector is unplugged)
The by Monolithic Power Systems (MPS) is a specialized one-chip solution that combines a 4-channel WLED backlight controller with a high-efficiency buck converter, primarily used in modern monitor and TV applications.
A working channel will have a low voltage (roughly 0.5V–1V). A channel with an open string will show close to the Boost voltage, while a shorted channel will show near 0V. 2. Monitor the OVP Pin
The OVP pin uses a resistor divider from the output to ground to set the threshold .