Monolithic Power Systems Inc. MP4031GS-Z

Overview

MP4031GS-Z 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 AC/DC LED drivers. It delivers accurate constant LED current (e.g., 350 mA) without secondary-side feedback or optocoupler, operates in boundary-conduction mode, achieves >0.98 power factor, and supports flicker-free dimming across extended phase-cut ranges. Used in residential and commercial LED retrofit lamps.

For engineers reviewing the MP4031GS-Z datasheet, MP4031GS-Z pinout, MP4031GS-Z application, or MP4031GS-Z equivalent, key selection criteria include primary-side real-current control accuracy, TRIAC dimming compatibility with 25% line-cycle blanking, analog dimming interface via CS/DIM pin, and integrated protections including OVP, OLP, OTP, and UVLO with auto-restart.

Technical Context

The MP4031 implements proprietary real-current control using primary-side signals-MULT pin voltage (0.13–0.38 V thresholds) and ZCD zero-current detection-to regulate LED current without secondary feedback. Its multiplier circuit (gain 0.84–1.26 V⁻¹) shapes input current to match rectified line voltage, enabling >0.98 PF and <12% THD at 120 VAC.

It operates in boundary-conduction mode with 5.6 µs minimum off-time and 450 ns leading-edge blanking on the CS/DIM pin. Dimming is handled via dual-path detection: MULT pin senses TRIAC turn-on phase (0.32–0.38 V threshold), while CS/DIM accepts 0–10 V analog signals-both modulating COMP voltage (1.9–5.0 V range) to scale output current linearly.

Key Specifications

Pinout & Package

MP4031GS-Z is housed in an 8-pin SOIC package (JEDEC MS-012AC), with exposed pad not present. Thermal performance supports 1.3 W continuous dissipation at +25°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP4031GS-Z, MP4030GS-Z removes analog dimming and internal MOSFET but retains TRIAC compatibility, while BP57728 trades active PFC and precision dimming for lower cost and higher integration-neither matches MP4031GS-Z's combination of high PF, dual-dimming support, and comprehensive protection.

Availability

MP4031GS-Z is available at Aetrix Electronics and suitable for residential LED retrofits, commercial downlights, industrial troffers, and outdoor streetlight drivers requiring stable component supply, long-lifecycle assurance, and RoHS-compliant manufacturing.

Supply support for MP4031GS-Z 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.

The MP4031 belongs to MPS's offline LED lighting controller product line, engineered specifically for single-stage, primary-side-regulated AC/DC LED drivers that demand high power factor, low THD, and seamless compatibility with both TRIAC and analog dimming infrastructures.

FAQ

What is the function of the MULT pin in MP4031GS-Z?

The MULT pin serves dual functions: it receives a scaled rectified line voltage to enable active power-factor correction, and it detects TRIAC dimmer phase angle via voltage thresholds (0.32–0.38 V for turn-on, 0.13–0.17 V for turn-off). Its 25% line-cycle blanking prevents false triggering during zero-crossing intervals, ensuring stable dimming response across the full range.

How does MP4031GS-Z achieve primary-side current regulation without secondary feedback?

MP4031GS-Z uses proprietary real-current control that correlates primary-side parameters-including ZCD timing, MULT voltage, and CS/DIM current sense-to calculate and regulate secondary LED current. The algorithm leverages transformer turns ratio, V_REF (0.4 V), and R_S to derive I_LED ≈ (N × V_FB) / (2 × R_S), eliminating need for optocoupler or secondary shunt regulator.

Can MP4031GS-Z operate without an auxiliary winding?

No. The ZCD pin requires connection to an auxiliary winding tap to detect zero-current crossing for boundary-mode control and OVP monitoring. While the internal VCC charging circuit enables initial start-up, sustained operation depends on auxiliary winding voltage to maintain VCC above 9 V-absence of auxiliary winding causes repeated UVLO cycling and failure to regulate.

What protection mechanisms trigger auto-restart versus latch-off?

All protections-OVP, OLP, OTP, and UVLO-trigger auto-restart: the IC halts switching, discharges COMP, and waits for VCC to drop below 7 V before recharging and resuming operation. There is no permanent latch-off mode; this behavior ensures recovery from transient faults like line surges or momentary overloads without manual reset.

Is MP4031GS-Z compatible with leading-edge or trailing-edge TRIAC dimmers?

MP4031GS-Z is optimized for leading-edge (standard TRIAC) dimmers, as confirmed by its MULT pin detection thresholds and typical application schematics. Trailing-edge (ELV) dimmer compatibility is not specified in the datasheet; performance may vary due to different voltage rise/fall characteristics and lack of dedicated ELV detection circuitry.

What is the maximum recommended output power for MP4031GS-Z in SOIC8 package?

At +25°C ambient, the SOIC8 package supports up to ~15 W continuous output with proper PCB copper area (≥2 cm² 2 oz copper per layer) and airflow. Derating is required above +60°C ambient-maximum output drops to ~8 W at +85°C case temperature due to θ_JA = 96°C/W and 150°C max junction limit.

Does MP4031GS-Z require an external MOSFET?

Yes. MP4031GS-Z integrates a low-side 30 V, 250 mΩ main MOSFET (pin 5 S and pin 6 D), but it is rated for ≤15 W applications. For higher power or 650 V isolation requirements, an external high-side MOSFET must be used-MP4031 drives its gate via the D pin's internal JFET charge pump and external bootstrap network.