Mp3378e Protection Pin Upd Fix — Exclusive

The MP3378E is a integrated circuit that combines a 4-channel White LED (WLED) controller and a high-efficiency synchronous buck converter into a single TSSOP-28 EP package. Technical Summary: MP3378E Protection Pin (OVP)

The primary "protection pin" on the MP3378E is the OVP pin (Pin 9). This pin is central to the device's Over-Voltage Protection (OVP) logic, which monitors the output voltage to prevent component damage in the event of an open-LED string or other voltage spikes. Pin Number: 9

Function: Triggers Over-Voltage Protection (OVP) when the voltage at this pin exceeds the internal threshold (typically 1.23V).

Implementation: It is typically connected to a resistor divider from the step-up converter's output to ground. This allows users to program the specific voltage level at which protection activates. Comprehensive Protection Features

The MP3378E includes several built-in safety mechanisms for both the WLED controller and the buck converter: Protection Type Mechanism / Details Over-Voltage (OVP)

Monitored via Pin 9; triggers when output exceeds set threshold. Over-Current (OCP)

Protects both the WLED controller and buck converter from excessive current. LED Protection Detects both open and shorted LED strings. Under-Voltage (UVP) Monitors for insufficient input/bus voltage. Thermal Protection

Includes Over-Temperature Protection (OTP) and recoverable thermal shutdown. Short Protection

Specialized protection for inductor and diode short circuits. Pin Configuration (TSSOP-28 EP) mp3378e protection pin upd

For hardware updates or drafting circuit schematics, the surrounding pinout for the protection circuit includes: Pin 1 (GND1): Ground reference for the WLED controller. Pin 8 (LED1): Monitoring for LED String 1. Pin 9 (OVP): Over-voltage protection threshold input.

Pin 23 (GATE): Drives the external MOSFET for the boost circuit. MP3378E - Mouser Electronics

is a integrated circuit from Monolithic Power Systems (MPS) designed for monitor applications. It combines a 4-string WLED controller for backlighting with a high-efficiency buck converter for internal power. MPS | Monolithic Power Systems The "protection pin" functionality primarily relates to the OVP (Over-Voltage Protection)

input, which is a critical feedback node used to monitor and protect the IC from fault conditions. Protection Pin Overview (OVP)

The OVP pin is a dedicated input that monitors the output voltage of the step-up converter to prevent catastrophic failures.

: It is typically connected to a resistor divider from the output voltage.

: If the voltage at the OVP pin exceeds a preset internal threshold, the IC shuts down the PWM generator and disables the MOSFET drivers to prevent thermal runaway or component damage. : This protects against open-circuit

conditions (e.g., a loose LED connection), where the boost converter would otherwise indefinitely increase voltage trying to maintain constant current. Comprehensive Protection Features The MP3378E is a integrated circuit that combines

The MP3378E integrates several protection modes for both the WLED controller and the buck converter: MPS | Monolithic Power Systems Controller Part Integrated Protections WLED Controller

OCP, OTP, UVP, OVP, LED Short/Open Protection, Inductor/Diode Short Protection Buck Converter Over-Current Protection (OCP), Thermal Shutdown Fault Handling & Updates LED Open/Short

: The IC monitors individual LED strings. If a string is detected as open or shorted, it can disable that specific string while keeping others active, or shut down depending on the severity. Thermal Protection

: Includes recoverable thermal shutdown, meaning the device will restart once it cools to a safe operating temperature. External Control MP3378E datasheet

specifies that the OVP threshold is programmable via external resistors to match the specific LED array's voltage requirements. MPS | Monolithic Power Systems schematic example of how to calculate the resistor values for the OVP pin? MP3378E - Monolithic Power Systems

3. Key Design Update (UPD): The "False OVP" Trap

A common field issue occurs when the C_PROT capacitor is too small. During start-up, the boost output rises. If the OVP divider reaches 2.0V before the PROT pin finishes its soft-start ramp (0→0.8V), the IC will falsely trigger OVP and shut down.

3.2 Leakage Current on the PROT Pin Trace

The PROT pin is high-impedance (~1MΩ). Flux residue, moisture, or conformal coating can create leakage paths.

Overview

The MP3378 is a boost controller designed to drive up to 8 parallel strings of white LEDs. To ensure system reliability and protect both the driver IC and the LED load, the device incorporates several protection mechanisms. These protections are primarily configured and monitored through specific pins: OVP (Over-Voltage Protection), PROG/OC (Current Setting/Protection), and the LEDx (String Fault) pins. more likely in a repair context

Step 5: Inspect Layout for Capacitive Coupling

Check if the PROT pin trace runs parallel to the SW (switching) node for more than 5mm. Switching spikes (up to 50V/ns) can couple into the PROT pin, causing false UPD. A 100pF capacitor from PROT to GND near the IC often resolves this.

1. PRO Pin Function

| PRO state | Protection response | |-----------|----------------------| | LOW (GND) | Latch-off mode – after fault (OVP, OCP, SCP, UVLO), driver shuts down and stays off until VCC cycled | | HIGH (>2V) | Auto-restart mode – after fault, driver tries to restart periodically (hiccup) |

✅ Use auto-restart (PRO high) for systems where temporary faults shouldn’t require power cycling.
⚠️ Latch-off is safer for permanent faults but requires user reset.

Section 7: Preventing UPD in New Designs

If you’re designing a product with the MP3378E, implement these best practices to avoid protection pin UPD issues in production.

6. Summary Table – Protection Pin Setup

| Requirement | PRO pin | UPD setting | |-------------|---------|--------------| | Latch-off on any fault | GND | Disabled (default) | | Auto-restart (hiccup) | >2V | Disabled | | Operate below 4.5V VIN | >2V (auto-restart) | Enabled | | Operate below 4.5V + latch-off | GND + external reset circuit | Enabled (rare) |

Would you like a reference schematic showing PRO pin connection and optional UPD circuit for the MP3378E?

Based on the component naming convention, the MP3378e typically refers to the Monolithic Power Systems (MPS) MP3378, a popular 8-string WLED driver controller.

While the standard MP3378 datasheet doesn't explicitly list a pin named "UPD" (it usually has PWM, EN, ISET, etc.), "UPD" in the context of LED drivers often refers to "Update" (as seen in the programming interface of similar MPS parts) or, more likely in a repair context, it is a shorthand or typo for OVP (Over-Voltage Protection) or PROG/Protection pin functions.

Below is the complete technical text regarding the Protection Pin functions and configuration for the MP3378.