Monolithic Power Systems Inc. MP4033GS

Overview

MP4033GS from Monolithic Power Systems is a TRIAC-dimmable, primary-side-control offline LED controller with integrated active PFC, designed for isolated flyback LED drivers up to 50W. It delivers accurate LED current regulation using real-current control, operates in boundary-conduction mode (BCM), and supports analog dimming via PWM input or phase-cut dimmers. Its integrated VCC charging circuit enables fast start-up, and NTC-based thermal fold-back extends LED lifetime.

For engineers reviewing the MP4033GS datasheet, MP4033GS pinout, MP4033GS application, or MP4033GS equivalent, key selection criteria include TRIAC dimmer compatibility (leading/trailing edge detection), programmable thermal fold-back threshold, ZCD-based zero-current switching timing, and multi-package availability (SOIC-8/MSOP-10/SOIC-14) for layout flexibility in compact lighting designs.

Technical Context

The MP4033GS implements proprietary real-current control by reconstructing secondary LED current from primary-side signals-using VREF (0.414 V), MULT pin sinusoidal reference, and S-pin current-sense resistor-eliminating optocoupler feedback. Its adaptive dimmer detection identifies leading-edge vs. trailing-edge types via VMULT thresholds (e.g., VMULT_LD_LOW = 0.10 V, VMULT_TL_HIGH = 0.45 V) and adjusts COMP clamp voltage (VCOMPL_LD = 1.88 V, VCOMPL_TL = 1.58 V) accordingly.

It enforces boundary-conduction mode via ZCD-triggered MOSFET turn-on after tZCD_LEB (2.3 µs typical), minimizing switching losses and EMI. Protection logic includes cycle-by-cycle OCP (VOCP = 2.70 V), output OVP (VZCD_OVP = 5.30 V), ZCD short-circuit detection (VZCD_SC = 100 mV, tZCD_SC_LEB = 33 ms), and auto-restart fault recovery tied to VCCEN (7.0 V).

Key Specifications

Pinout & Package

MP4033GS is packaged in SOIC-8 with exposed pad (no thermal pad specified), rated for 1.3 W continuous power dissipation at TA = 25 °C (θJA = 96 °C/W). Pin functions are validated per MPS datasheet Rev. 1.0 (2014), with all pins electrically defined and no NC pins in SOIC-8 configuration.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TRIAC-dimmable offline LED controller applications.

Compared with NCL30000 and AL1676, MP4033GS offers superior dimmer interoperability through adaptive detection, faster start-up via integrated charging, and comprehensive protection including ZCD short-circuit lockout-making it optimal for cost-sensitive, high-reliability residential and commercial LED drivers.

Availability

MP4033GS is available at Aetrix Electronics and suitable for residential LED downlights, commercial office lighting, and industrial high-bay fixtures requiring stable component supply, long-lifecycle support, and RoHS-compliant manufacturing.

Supply support for MP4033GS 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, headquartered in Kirkland, WA, with global design and support centers.

The MP4033GS belongs to MPS's LED lighting controller product line, engineered specifically for TRIAC-dimmable, single-stage isolated LED drivers targeting energy-efficient solid-state lighting up to 50 W.

FAQ

What dimmer types does MP4033GS support?

MP4033GS supports both leading-edge (TRIAC) and trailing-edge (electronic low-voltage) dimmers. It automatically detects dimmer type using MULT pin voltage thresholds and timing windows-VMULT_LD_HIGH = 0.28 V for leading edge, VMULT_TL_HIGH = 0.45 V for trailing edge-with tLEADING = 100 µs and tTRAILING = 450 µs detection latency.

How does MP4033GS achieve primary-side current regulation without an optocoupler?

MP4033GS uses proprietary real-current control: it reconstructs LED current from primary-side signals-including VREF (0.414 V), MULT pin line-synchronized reference, and S-pin sense voltage-calculating I_LED ≈ (V_REF × N_sec) / (2 × R_s). This eliminates optocoupler dependency while maintaining ±3% current accuracy across line and load variations.

What is the role of the DAMP pin?

The DAMP pin (Pin 4) drives an external MOSFET in an RC snubber network to suppress voltage ringing during main MOSFET turn-off. It sources 370 µA typical pull-down current and clamps at 15 V, reducing EMI and preventing false triggering of ZCD or OVP circuits in high dv/dt flyback topologies.

Does MP4033GS support analog dimming with PWM input?

Yes-MP4033GS supports analog dimming via PWM input applied to the NTC pin through a 1 kΩ resistor. The internal circuit converts PWM duty cycle into proportional current fold-back, enabling smooth brightness control independent of TRIAC phase-cut position. DIM pin also supports external FET control for warm sunset applications.

What protections are included and how do they recover?

MP4033GS includes output OVP (5.30 V), OCP (2.70 V), ZCD short-circuit (100 mV for 33 ms), over-temperature (150 °C), and VCC UVLO (7.0 V). All protections trigger auto-restart: after fault, VCC drops below VCCEN, re-enabling internal charging and resuming switching once VCC rises above VCCH (10.0 V).

Can MP4033GS be used in non-isolated buck-derived topologies?

No-MP4033GS is designed exclusively for isolated flyback topologies with transformer-coupled auxiliary winding for ZCD sensing and VCC supply. Its real-current control algorithm, OVP sampling, and ZCD timing rely on reflected auxiliary voltage; non-isolated configurations lack this critical feedback path and violate absolute maximum ratings on ZCD and MULT pins.