Monolithic Power Systems Inc. MP4021GS-A-Z

Overview

MP4021GS-A-Z from Monolithic Power Systems is a primary-side control offline LED controller with integrated active PFC, implemented in SOIC8 package. It delivers ±1.5% load regulation, ≥0.9 power factor over universal input (85–265VAC), and operates in boundary conduction mode to minimize MOSFET switching losses. Used in isolated single-stage LED drivers for residential lighting where optocoupler-free design reduces BOM cost and improves reliability.

For engineers reviewing the MP4021GS-A-Z datasheet, MP4021GS-A-Z pinout, MP4021GS-A-Z application, or MP4021GS-A-Z equivalent, key selection criteria include real-current control accuracy, VCC UVLO thresholds (12.6V turn-on / 9.0V turn-off), 20µA start-up current, 1mA quiescent current, and ZCD-based OVP/OCP timing (1.5µs/280ns blanking).

Technical Context

The MP4021GS-A-Z employs proprietary real-current control that derives LED current regulation solely from primary-side signals-eliminating secondary feedback and optocouplers. Its multiplier architecture accepts rectified line voltage at MULT and COMP reference to generate sinusoidal peak-current references, enabling active PFC with THD <15% and PF ≥0.9 across 85–265VAC.

Boundary conduction mode (BCM) operation is enforced via zero-current detection on ZCD, triggering MOSFET turn-on when auxiliary winding voltage falls below 0.31V after 1.8–3.2µs blanking. Protection logic includes cycle-by-cycle current limiting (CS clamp at 2.5V), auto-restart over-temperature shutdown, and output OVP triggered at 5.4V on ZCD after 1.5µs delay.

Key Specifications

Pinout & Package

MP4021GS-A-Z is housed in an SOIC8 package (5.0mm × 6.0mm, 1.27mm pitch) with exposed pad not electrically connected. Thermal resistance θ_JA = 96°C/W on JEDEC 4-layer board.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP4021GS-A-Z, MP4026GS-Z offers superior line/load regulation and longer manufacturer support, while MP4027GS-Z trades external MOSFET flexibility for integration-making MP4021GS-A-Z optimal for legacy redesigns requiring identical pinout and proven thermal behavior in 30–60W industrial fixtures.

Availability

MP4021GS-A-Z is available at Aetrix Electronics and suitable for residential LED bulbs, commercial downlights, industrial high-bay fixtures, and outdoor street lighting requiring stable component supply and long-term obsolescence management.

Supply support for MP4021GS-A-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 over 20 years of leadership in DC/DC converters, LED drivers, and motor drivers.

The MP4021A product line was designed specifically for cost-sensitive, high-efficiency offline LED lighting applications requiring primary-side regulation, active PFC, and robust protection-all in a single SOIC8 package.

FAQ

What is the function of the FB/NC pin on MP4021GS-A-Z?

The FB/NC pin is internally disconnected in primary-side constant-current mode and must be left floating. It becomes active only in constant-voltage configurations, where it accepts an external voltage divider from the auxiliary winding to regulate output voltage via the internal 0.414V error amplifier reference. Misconnecting this pin in CC mode causes regulation failure.

How does the MP4021GS-A-Z achieve power factor correction without a dedicated PFC controller?

It uses the MULT pin to sample the rectified AC line voltage and multiplies it with the COMP voltage (derived from LED current feedback) to generate a sinusoidal current reference. This forces the primary peak current to track the input voltage waveform, achieving ≥0.9 PF without additional ICs or boost stages.

What is the purpose of the 1.5µs blanking time on the ZCD pin for OVP detection?

The 1.5µs blanking period prevents false OVP triggering caused by ringing or voltage spikes immediately after MOSFET turn-off. During this interval, the ZCD comparator is disabled, ensuring OVP only responds to sustained overvoltage conditions on the auxiliary winding-critical for reliable operation in noisy EMI environments.

Can MP4021GS-A-Z drive a 600V MOSFET directly?

Yes-the GATE pin provides 1A source / 1.2A sink capability with 13.5V output clamp, sufficient to drive standard 600V superjunction MOSFETs (e.g., STP6NK60ZFP, IPP60R099C6) with gate charge ≤35nC. Layout must minimize gate loop inductance to prevent oscillation during fast switching.

Why does MP4021GS-A-Z specify "Not Recommended for New Designs"?

MPS discontinued active development of MP4021A in favor of MP4026/MP4027, which offer improved line regulation, lower start-up current, and extended temperature range. MP4021GS-A-Z remains available for legacy repair and existing production, but new designs should use MP4026GS-Z for full technical and lifecycle support.

How is over-temperature protection implemented in MP4021GS-A-Z?

An on-die thermal sensor triggers auto-restart OTP when junction temperature exceeds 150°C. The IC halts switching, enters quiescent mode, and resumes operation only after VCC drops below 9.0V UVLO threshold-ensuring full thermal recovery before restart and preventing thermal runaway in enclosed fixtures.