Monolithic Power Systems Inc. MP4031GS-P

Overview

MP4031GS-P from Monolithic Power Systems is a TRIAC- and analog-dimmable, primary-side-controlled offline LED controller with integrated active PFC, designed for isolated single-stage LED drivers. It delivers accurate constant-current regulation (±5% typical) using proprietary real-current control, operates in boundary-conduction mode (BCM), achieves >0.98 power factor, and supports flicker-free dimming down to 5% output current. It targets residential and commercial LED retrofit lamps requiring compact, optocoupler-free designs.

For engineers reviewing the MP4031GS-P datasheet, MP4031GS-P pinout, MP4031GS-P application, or MP4031GS-P equivalent, key selection criteria include its integrated low-side MOSFET (30 V, 250 mΩ), 8-pin SOIC package, TRIAC phase-detection threshold (0.35 V), analog dimming input compatibility at CS/DIM, and auto-restart protection architecture.

Technical Context

The MP4031GS-P implements primary-side regulation via a proprietary real-current–control loop that reconstructs secondary LED current from primary-side sensing-eliminating optocouplers and secondary feedback. Its multiplier circuit (VMULT input) shapes the inductor peak current to match the rectified AC line waveform, enabling active PFC without dedicated PFC controllers.

TRIAC dimming is handled by detecting phase angle via the MULT pin (0.15 V turn-off / 0.35 V turn-on thresholds) with 25% line-cycle blanking; analog dimming is implemented by injecting a 0–10 V signal into the CS/DIM pin, which modulates the internal current reference while maintaining COMP clamp at 1.9 V to preserve TRIAC holding current.

Key Specifications

Pinout & Package

MP4031GS-P is housed in an industry-standard 8-pin SOIC package (SOIC8), surface-mount, with exposed pad not present. Pin functions are validated per MPS MP4031 Rev. 1.03 datasheet.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar primary-side LED controller applications.

Compared with MP4032GS-P, MP4031GS-P offers tighter integration and lower system cost for ≤18 V LED strings, while BP5778E sacrifices dimming capability and primary-side accuracy for raw component cost reduction-making MP4031GS-P optimal for dimmable, compact, and thermally constrained designs.

Availability

MP4031GS-P is available at Aetrix Electronics and suitable for residential LED retrofit lamps, commercial downlight drivers, and industrial panel-mount fixtures requiring stable component supply, RoHS-compliant packaging, and long-lifecycle availability.

Supply support for MP4031GS-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 global manufacturing partnerships.

The MP4031 belongs to MPS's offline LED driver product line, engineered specifically for cost-sensitive, space-constrained, and dimmable AC/DC LED lighting applications requiring high PF, low THD, and seamless TRIAC compatibility.

FAQ

What is the maximum LED string voltage supported by MP4031GS-P?

The MP4031GS-P integrates a 30 V low-side MOSFET with 250 mΩ R_DS(on). In practice, this limits safe operation to LED string voltages ≤18 V under worst-case conditions (including line surges and reflected transients). For higher-output-voltage designs, MP4032GS-P (40 V MOSFET) is recommended.

Does MP4031GS-P require an external MOSFET?

No. MP4031GS-P integrates a low-side 30 V / 250 mΩ MOSFET, eliminating the need for an external switch in most ≤15 W LED driver applications. The D and S pins connect directly to the transformer primary and sense resistor, respectively.

How does MP4031GS-P achieve flicker-free TRIAC dimming?

It combines three techniques: (1) 25% line-cycle blanking to reject noise during zero-crossing, (2) COMP pin clamping at 1.9 V during deep dimming to maintain minimum TRIAC holding current, and (3) real-current control that dynamically adjusts peak inductor current per half-cycle to match dimmed input power.

Can MP4031GS-P operate without an auxiliary winding?

No. The ZCD pin requires a voltage signal from an auxiliary winding to detect zero-current crossing for BCM operation and OVP monitoring. The auxiliary winding also supplies VCC after startup-omitting it prevents stable regulation and disables critical protections.

What is the purpose of the internal charging circuit at the D pin?

The D pin connects internally to a JFET that charges the VCC capacitor from the drain node during MOSFET off-time. This ensures fast startup (<115 µs timer) without relying solely on the auxiliary winding, eliminating perceptible delay in lamp turn-on-even under low-line or cold-start conditions.

Is MP4031GS-P RoHS-compliant and halogen-free?

Yes. MP4031GS-P is lead-free and fully compliant with the EU RoHS directive. MPS confirms green status (halogen-free, antimony-free) per its Quality Assurance documentation-verified on the official MPS website under Products > Quality Assurance.

What is the minimum recommended sense resistor (R_S) value for stable operation?

The CS/DIM pin has a current-sense comparator with 2.3 V upper clamp and 450 ns leading-edge blanking. To ensure reliable detection and avoid noise-induced false triggering, R_S must yield ≥100 mV sense voltage at minimum expected LED current. For 350 mA output, R_S ≥ 0.286 Ω is recommended; 0.33 Ω is commonly used for margin.