Monolithic Power Systems Inc. MP4657AGS-P

Overview

MP4657AGS-P from Monolithic Power Systems is a single-stage flyback LED driver and system voltage controller for secondary-side LCD backlighting, integrating 4-string LED current balancing (±2% matching), 1.5% system voltage regulation accuracy, and independent PWM/analog dimming control via ADIMP/PWM pin with 5 kHz threshold. It drives an external N-channel MOSFET to regulate VSYS while controlling flyback power stage for LED current, used in flat-panel display power architectures.

For engineers reviewing the MP4657AGS-P datasheet, MP4657AGS-P pinout, MP4657AGS-P application, or MP4657AGS-P equivalent, key selection criteria include its dual-loop control architecture (ICOMP for LED current, DCOMP for VSYS duty cycle), SOIC-16 package thermal performance (θJA = 80°C/W), soft-switching synchronization via SYNC pin, and comprehensive fault protection including LED open/short, OVP, and thermal shutdown at 150°C.

Technical Context

The MP4657AGS-P implements individual closed-loop control: ICOMP regulates LED current using minimum VLEDx feedback against VLED_REF, while DCOMP adjusts external MOSFET duty cycle for system voltage regulation when PWM is active; when PWM is inactive, DCOMP controls flyback directly. Its transconductance differs by mode-GM_DCOMP_ON = 680 μA/V vs. GM_DCOMP_OFF = 260 μA/V-enabling precise dynamic response across operating states.

SYNC pin synchronizes GATE falling edge to primary-side flyback switch rising edge, enabling zero-current turn-on of the external N-MOSFET via leakage inductance transfer, reducing voltage spikes and switching loss. Protection logic includes latched OVP (3V threshold on OVP pin), feedback open-loop detection (50% VREF_VFB saturation), and multi-level LED fault sensing: fast OV (20V), slow OV (4.9V), and open-string detection (100mV).

Key Specifications

Pinout & Package

MP4657AGS-P is housed in a 16-pin SOIC package (JEDEC MS-012AC, 1.27 mm pitch) with exposed pad for thermal enhancement; θJA = 80°C/W on 4-layer PCB per JESD51-7.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver and system voltage controller applications.

Compared with MP4655AGS, MP4657AGS-P adds two LED strings, tighter current matching (±1.5% vs unspecified), and diagnostic ISET/FAULT; versus UCC28810DR, it eliminates need for external LED drivers and provides direct analog/PWM dimming-reducing total solution size and component count by ≥30%.

Availability

MP4657AGS-P is available at Aetrix Electronics and suitable for LCD monitor backlighting, smart TV power systems, flat panel video displays, and commercial digital signage requiring stable component supply and long-term manufacturability.

Supply support for MP4657AGS-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 power management ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP4657A product line targets secondary-side LED backlight controllers for consumer and commercial displays, emphasizing integration of LED current regulation, system voltage control, and robust protection in compact packages.

FAQ

What dimming methods does MP4657AGS-P support and how are they configured?

The MP4657AGS-P supports both analog and PWM dimming via the ADIMP/PWM pin. Apply a pulse signal ≥5 kHz for analog dimming (duty cycle controls LED current amplitude); apply <5 kHz for PWM dimming (high/low states enable/disable LED current). The device internally detects frequency and routes signal to appropriate control path without external configuration.

How does the MP4657AGS-P achieve soft switching of the external N-MOSFET?

Soft switching is achieved by synchronizing the GATE signal's falling edge to the primary-side flyback switch's rising edge via the SYNC pin. This ensures the N-MOSFET turns off when secondary winding current approaches zero, minimizing voltage spikes. Gate turn-on occurs with near-zero current due to leakage inductance energy transfer, reducing switching loss.

What protections are implemented for the LED driver stage?

The LED driver stage includes LED open protection (100 mV threshold), LED short protection (fast OV at 20 V, slow OV at 4.9 V), and LEDx pin short-to-ground detection. All faults trigger ISET/FAULT pin low assertion and can latch off the IC if OVP pin exceeds 3 V, preventing damage to LEDs or PCB traces.

Can MP4657AGS-P regulate both LED current and system voltage simultaneously?

Yes-when PWM is active, MP4657AGS-P uses ICOMP to regulate LED current via the flyback power stage and DCOMP to control the external N-MOSFET's duty cycle for system voltage regulation. When PWM is inactive, DCOMP directly regulates system voltage through the flyback stage while LED current is disabled.

What is the role of the OPT pin and how does it interface with the primary-side controller?

The OPT pin outputs a compensation signal that drives the LED side of an optocoupler, feeding error information back to the primary-side flyback controller. During normal operation, it swings between 0.8 V and 2.3 V; during OVP latch-off, it clamps to 3.3 V to halt primary switching, providing galvanically isolated system-level protection.

How is LED current set and what tolerance does it maintain?

LED current is set by connecting a resistor from ISET/FAULT to GND; VISET = 1.58 V (typical), yielding ILED = 1.58 V / RISET. At 50 mA, current accuracy is ±1.5%; current matching across 4 strings is ±2%. Temperature drift is minimized by internal reference tracking-VISET varies only ±10 mV from –40°C to +100°C.

What thermal management features ensure reliability in enclosed display enclosures?

MP4657AGS-P includes junction temperature monitoring with shutdown at 150°C and 25°C hysteresis, plus SOIC-16 package with thermal pad for PCB copper pour attachment. Its 1.56 W max power dissipation at 25°C ambient and 80°C/W θJA allow safe operation in thermally constrained spaces when paired with ≥2 cm² of 2-oz copper.