Monolithic Power Systems Inc. MP4655GY-P

Overview

MP4655GY-P from Monolithic Power Systems is a pure single-stage LLC controller for LED backlighting systems, located on the secondary side of large LCD TVs and monitors. It simultaneously regulates LED current (via CC loop) and system supply voltage (via CV loop), supports 9–35V input, delivers 180° phase-shifted gate drive signals, and integrates PWM/analog dimming with fast-response dimming MOSFET control.

For engineers reviewing the MP4655GY-P datasheet, MP4655GY-P pinout, MP4655GY-P application, or MP4655GY-P equivalent, key selection considerations include its dual-loop CC/CV frequency control architecture, SOIC-28 package with 28-pin secondary-side interface, capacitive-mode protection logic, integrated fault indicator (IOCP/FAULT), and support for both deep PWM dimming and DC/pulse analog dimming inputs.

Technical Context

The MP4655GY-P implements a dual-loop control architecture: a current-mode loop (IFB → ICOMP) regulating LED string current and a voltage-mode loop (VFB → VCOMP) regulating system bus voltage, both feeding into an LLC frequency/duty control engine. Its FSET/SS network sets operating frequency (20–350 kHz), while CMODE and FTH_CMODE pins enable real-time capacitive-mode detection and forced frequency shift to avoid hard switching.

It drives two external LLC half-bridges via GL/GR outputs (12V gate drivers with 2Ω pull-down/8Ω pull-up) and independently controls an extra N-channel MOSFET via GATEN (with dedicated charge-pump VDR_DN supply). Protection logic includes per-cycle OCP on VOCP and IOCP/FAULT, open/short LED detection via IFB/VLED1/VLED2 thresholds, and latch-up behavior triggered by sustained faults exceeding defined delay windows.

Key Specifications

Pinout & Package

MP4655GY-P is housed in a SOIC-28 package with exposed thermal pad (pin 28 = GND), optimized for secondary-side placement in isolated LED backlight supplies. Pin layout supports full isolation barrier routing with dedicated feedback, gate drive, and protection signal groups.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED backlighting controller applications.

Compared with UCC28064A and LM3445MMX/NOPB, MP4655GY-P uniquely integrates secondary-side LLC control, dual-loop CC/CV regulation, and hybrid dimming in one SOIC-28 package-reducing solution size by 45% and enabling >92% efficiency in large-screen TV applications where cross-regulation and acoustic noise are critical.

Availability

MP4655GY-P is available at Aetrix Electronics and suitable for large-screen LCD TVs, commercial display monitors, and outdoor LED lighting systems requiring stable component supply, long-lifecycle support, and RoHS-compliant manufacturing.

Supply support for MP4655GY-P includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with design centers in the US, China, and Taiwan, and manufacturing partners qualified to AEC-Q200 and ISO 9001 standards.

The MP4655 belongs to MPS's LED Backlight Controller product line, engineered specifically for high-efficiency, low-noise, single-stage LLC architectures in premium TV and display applications where secondary-side precision regulation and fast dimming response are mandatory.

FAQ

What is the function of the FTH_CMODE pin?

FTH_CMODE sets the frequency threshold (typically 91 kHz) above which the MP4655GY-P will latch the LLC stage upon capacitive mode detection. A resistor from FTH_CMODE to GND sources current that programs this threshold; exceeding it during capacitive resonance triggers immediate fault shutdown to protect MOSFETs from hard switching.

How does the MP4655GY-P handle LED string open-circuit protection?

Open LED protection activates when IFB voltage drops below 50% of its reference (e.g., <99.5 mV) for 1024 consecutive cycles while ICOMP is saturated. This causes the IC to disable DIMO, halt LLC switching, and assert IOCP/FAULT - preventing uncontrolled voltage rise across the open string and protecting downstream components.

Can ADIM and ADIMP be used simultaneously?

No - ADIM (DC analog dimming) and ADIMP (pulse analog dimming) are mutually exclusive. When ADIM voltage is applied, ADIMP is automatically disabled. If both are driven, ADIM takes precedence; ADIMP must be pulled high or left floating when ADIM is active to avoid undefined behavior.

What is the purpose of the VLED1 and VLED2 pins?

VLED1 and VLED2 provide differential voltage feedback for LED string protection. In 2-string designs, they monitor individual string voltages; in 1-string designs, they are shorted. The IC detects overvoltage (2.41 V threshold), inter-string voltage mismatch, and short-to-ground faults - triggering latch-up if VLED1–VLED2 exceeds 24 kΩ × 16 mA.

Does the MP4655GY-P support burst mode operation?

Yes - burst mode activates when VCOMP, VFB, ICOMP, or IFB fall below their respective thresholds (e.g., VFB < 0.95 × VREF_VFB). During burst mode, the IC skips LLC switching cycles to reduce standby power to <0.8 mA, while maintaining regulation readiness and fast wake-up (<1 ms) upon dimming command.

What thermal protection mechanisms are built in?

The MP4655GY-P includes junction temperature monitoring with thermal shutdown at 150°C. When exceeded, all gate drivers disable, soft-start capacitor discharges, and IOCP/FAULT asserts. Recovery occurs only after die temperature falls below 135°C hysteresis, ensuring safe re-entry without oscillation.

Is the SOIC-28 package lead-free and RoHS compliant?

Yes - MP4655GY-P is fully lead-free, halogen-free, and compliant with EU RoHS Directive 2011/65/EU and China RoHS II. MPS confirms green status per IPC-1752A reporting; full compliance documentation is available on the MPS Quality Assurance portal.