Monolithic Power Systems Inc. MP4658GS-P

Overview

MP4658GS-P from Monolithic Power Systems is a 4-string, secondary-side LED driver IC for LCD backlighting control in monitors and small TVs. It regulates LED current up to 200mA per string with ≤2% accuracy and 1.5% inter-string matching, operates from 6V–36V input, supports analog/PWM dimming, and integrates open/short LED, OVP, and thermal protection.

For engineers reviewing the MP4658GS-P datasheet, MP4658GS-P pinout, MP4658GS-P application, or MP4658GS-P equivalent, this page delivers verified functional context, SOIC-16 package mapping, real-world dimming interface behavior, and protection-triggering thresholds - all critical for flyback-based LED backlight system design and fault analysis.

Technical Context

The MP4658GS-P implements dual-loop regulation: COMP1 controls the flyback power stage during PWM-on periods to regulate minimum VLEDx across four strings, while COMP2 manages output voltage (VOUT) regulation during PWM-off periods via FB feedback. Its internal error amplifiers feature 70dB DC gain and 1MHz GBW with clamped output voltages (1V–2.5V) for stable loop compensation.

Dimming is implemented through two independent pins: ADIM accepts >5kHz signals for analog dimming (with impedance-dependent soft-start), while PDIM accepts low-frequency PWM (<100Hz) for direct current chopping. Fault detection includes LEDx short-to-ground (via COMP1 saturation + 30ms timeout), open LED (OVP pin ≥2.4V + VLEDx <100mV), and thermal shutdown at 150°C with 25°C hysteresis.

Key Specifications

Pinout & Package

MP4658GS-P is housed in a standard SOIC-16 package with gull-wing leads, optimized for thermal dissipation (θJA = 80°C/W) and compatibility with automated assembly. Pin 1 is marked by a notch or dot; pin numbering follows standard counter-clockwise convention from top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-string LED driver applications.

Compared with MP4658GS-P, the MPQ4658-AEC1 adds automotive qualification but increases BOM cost and footprint; the LT3761 requires additional components to achieve comparable 4-string performance and lacks native fault signaling - making MP4658GS-P optimal for cost-sensitive, high-integration backlight systems.

Availability

MP4658GS-P is available at Aetrix Electronics and suitable for LCD monitor backlighting, small-TV LED drivers, and commercial flat-panel displays requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP4658GS-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.

The MP4658 product line targets secondary-side LED backlight control in consumer and industrial displays, emphasizing integration of dimming, protection, and flyback interface functions in a single SOIC-16 package.

FAQ

What is the maximum LED string voltage the MP4658GS-P can handle?

The MP4658GS-P supports up to 80V return voltage per LED string, verified by absolute maximum rating (LEDx pin: –0.3V to +80V) and typical application circuits using 40V–60V LED stacks. This enables use with 20–25 white LEDs in series at 3V forward voltage each, with margin for voltage ripple and OVP headroom.

How does the MP4658GS-P implement LED current balancing across four strings?

It uses a min(VLEDx)-based regulation architecture: the internal error amplifier compares the lowest sensed VLEDx (from LED1–LED4) against a reference derived from ISET voltage. This ensures all strings share identical current without individual current-sense resistors, achieving ≤1.5% matching per datasheet test conditions.

Can the MP4658GS-P operate without an optocoupler?

No - the OPT pin is designed exclusively to drive an external optocoupler (e.g., PC817) for isolated feedback to the primary-side flyback controller. There is no internal isolation or alternative interface; removing the optocoupler breaks the control loop and prevents regulation of either VOUT or ILED.

What happens when both ADIM and PDIM pins are driven simultaneously?

The device enters analog-PWM hybrid mode: ADIM sets peak current amplitude via duty cycle, while PDIM chops that current at low frequency. The result is soft-ramping LED current transitions (reducing audible noise) synchronized to the PDIM edge timing - confirmed in Figure 8 of the datasheet.

Is the FF pin active-high or active-low during fault conditions?

The FF pin is an open-drain output that pulls low during any detected fault (open LED, short LED, OVP, thermal shutdown, or FB open). It remains high-impedance otherwise. An external pull-up resistor (typically 10kΩ to VSYS) is required to generate a valid logic-high signal in normal operation.

Does the MP4658GS-P support constant-voltage (CV) mode independently of PWM dimming?

Yes - CV mode activates automatically when PDIM is held low for ≥30ms, disabling the LED stage and switching regulation to the FB pin. In this mode, COMP2 controls the flyback to maintain VOUT, while protections like FB OVP and thermal shutdown remain fully active.

What is the recommended PCB layout practice for minimizing noise on COMP1 and COMP2 pins?

Place 100nF ceramic decoupling capacitors and RC compensation networks within 2mm of the respective COMP pins, route traces away from switching nodes (e.g., LEDx, OPT), and isolate analog ground (GND pin) from power ground using a single-point star connection - as specified in Section 15 (PCB Layout Guidelines) of the datasheet.