Mp3378e Protection Pin Upd Jun 2026
The protection architecture of the MP3378E is designed to monitor three critical failure modes: LED open circuits, LED short circuits, and power component (inductor/diode) failures.
| Pin Name | Pin # | Function & Protection Relevance | | :--- | :--- | :--- | | | 20 | Bootstrap for buck converter high-side driver. Critical for gate drive; must be monitored for UVLO condition. | | SYNC | 21 | Synchronization input for buck converter. Connect external clock (250kHz-2MHz) to synchronize switching. | | ISENSE | 22 | Current sense input for WLED controller. Senses external inductor current for peak current-mode control and OCP detection. | | GATE | 23 | Power switch gate output for WLED controller. Drives external N-channel MOSFET; OCP detection involves monitoring gate drive. | | VIN1 | 24 | Supply input for WLED controller. Monitored for UVP. | | VCC1 | 25 | Internal 6V linear regulator output for WLED controller. Supplies external MOSFET driver and internal circuitry; bypass to GND. | | COMP | 26 | Error amplifier output for WLED controller. Used for loop compensation; COMP voltage clamping used in inductor/diode short protection. | | EN1 | 27 | Enable input for WLED controller. Pull high to enable; logic-level control for startup/shutdown. | | PWM | 28 | PWM brightness control input. Used for dimming only; not for enabling/disabling controller. | | LED1-4 | 14,13,12,11 | LED string current sense inputs. Monitor LEDX voltages for open/short string detection. | | OVP | 8 | Over-voltage protection sense input. Set OVP threshold via external resistor divider. | | FB | 9 | Feedback for buck converter. Used for output voltage regulation and OVP detection. | | EN2 | 10 | Enable input for buck converter. Pull high to enable; shutdown controlled by EN2, VIN2 UVLO, or thermal shutdown. | | VIN2 | 18,19 | Supply input for buck converter. Monitored for UVLO. | | SW | 20 | Switching node for buck converter. High-dv/dt node; keep away from sensitive analog areas. | | AGND | 21 | Analog ground reference for buck converter. Connect single-point to GND1. | | VCC2 | 22 | Internal 5V regulator output for buck converter. | | GND2 | 23,24 | Power ground for buck converter. | | ADIM | 16 | Analog dimming control. Supports PWM or DC signal for LED current adjustment. |
: 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 MPS MP3378E features a robust matrix of protection logic designed to isolate hazardous faults before they cause component degradation or fire risks. Protection Type Target Component Trigger Condition IC Response State Boost Output Rail Voltage exceeds programmed divider limit Latch-off / Gate Drive Stops OCP (Over-Current) Inductor / Power FET Peak current exceeds safe hardware threshold Hiccup Mode / Cycle-by-Cycle LED Short / Open WLED Strings Any channel pin drops to GND or floats high Disables faulty channel / Latch-off Diode/Inductor Short Boost Stage Abnormal dV/dt or dead short across power path Immediate Latch-off OTP (Thermal) Die Junction Junction temperature exceeds 150°C Auto-recoverable Shutdown Critical Pins in the Protection Loop mp3378e protection pin upd
The pin’s behavior is defined by its and an internal current source .
For the WLED controller section, minimize the loop formed by the external MOSFET (M1), output diode (D1), and output capacitors (C2, C3) to reduce EMI noise. Proper ground plane separation is critical—separate power ground (PGND) from signal ground (GND), connecting them at a single point, as all logic signals reference the signal ground plane. For the buck converter section, keep input ground connections to GND2 as short and wide as possible. Similarly, minimize the length and width of connections between input capacitors (C16, C16A, C17) and VIN2. Ensure all feedback connections (FB, COMP) are short and direct, placing feedback resistors and compensation components as close to the chip as possible. Route the SW node away from sensitive analog areas like FB. Always connect a resistor (R23) from SYNC to AGND, as SYNC is sensitive to noise—failure to do so may cause short-circuit protection to fail and damage the buck converter. Finally, connect GND1 and GND2 together by a single point to avoid ground loops.
If you want, I can:
RDS(ON)cap R sub cap D cap S open paren cap O cap N close paren end-sub
In modern LCD display systems (TVs, monitors, automotive displays), the LED backlight driver is critical. Among the leading solutions is the from Monolithic Power Systems (MPS), a highly integrated boost controller with 8-channel current sinks.
: Defeating built-in hardware protection loops violates original manufacturing tolerances, posing safety risks and invalidating commercial equipment standard compliances. The protection architecture of the MP3378E is designed
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:
In repair scenarios where a monitor shuts down due to aging LEDs (causing a "protection trip"), technicians sometimes modify the OVP circuit. However, for the MP3378E, the protection is .
