Monolithic Power Systems Inc. MP4050AGJ-P

Overview

MP4050AGJ-P from Monolithic Power Systems is a non-isolated, constant-current LED driver IC with an integrated 500V/8Ω MOSFET, designed for AC/DC LED bulb replacement applications. It delivers accurate 115mA LED current from universal 85–265VAC input using internal averaging feedback, operates above 22kHz to suppress audible noise, and includes thermal foldback (145°C start), OVP (2.0V threshold), and auto-restart protection.

For engineers reviewing the MP4050AGJ-P datasheet, MP4050AGJ-P pinout, MP4050AGJ-P application, or MP4050AGJ-P equivalent, key selection criteria include its TSOT23-5 package footprint, high-voltage direct DRAIN input capability, VCC UVLO hysteresis (0.24V), integrated 200ns leading-edge blanking, and thermal shutdown recovery at 110°C - all critical for compact, cost-sensitive, off-line LED drivers.

Technical Context

The MP4050AGJ-P implements a high-side buck topology with internal MOSFET switching controlled by peak-current limiting and average current regulation. Its feedback loop samples SOURCE voltage across an external sense resistor to maintain constant LED current via VREF = 0.196V reference, while minimum off-time (4.7μs) and maximum on-time (25μs) enforce DCM operation above 22kHz.

Thermal management combines two-stage protection: gradual current foldback begins at 145°C junction temperature, and hard thermal shutdown occurs at 160°C with 50°C hysteresis. Protection logic integrates open-LED detection via PRO pin (2.0V OVP threshold, 32μs response), short-circuit recovery, and latch-off mode with 18μA VCC discharge current.

Key Specifications

Pinout & Package

MP4050AGJ-P is housed in a thermally enhanced TSOT23-5 package with exposed drain pad for improved heat dissipation. The 5-pin configuration supports minimal external component count in high-density LED driver PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with MP4050AGS, MP4050AGJ-P offers identical functionality in a 30% smaller footprint but trades 0.05W thermal margin; versus BP5758D, it delivers superior thermal resilience and integration at modest BOM cost increase - making it optimal for space-constrained, reliability-focused LED bulb designs.

Availability

MP4050AGJ-P is available at Aetrix Electronics and suitable for smart residential LED bulbs, industrial panel indicator lights, and commercial downlight retrofit modules requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP4050AGJ-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 distribution since 1997.

The MP4050A product line targets cost-sensitive, non-isolated LED lighting applications - prioritizing integration, thermal robustness, and acoustic silence to replace traditional magnetic transformers and discrete drivers in retrofit bulbs.

FAQ

What input voltage range does MP4050AGJ-P support?

MP4050AGJ-P operates from universal AC inputs (85–265VAC) after full-wave rectification, or from DC sources as low as 12V. Its internal 500V MOSFET and HV startup current source enable direct connection to rectified mains without external pre-regulation, supporting both high-line and low-line configurations in single-design platforms.

How is LED current set and how accurate is it?

LED current is set by a single external sense resistor (R_S) between SOURCE and GND, using I_OUT = 0.196V / R_S. Accuracy is ±5% over –40°C to +125°C junction temperature, verified by characterization; 1% tolerance resistors with ≤±400ppm/°C TCR are recommended to maintain regulation across thermal extremes.

Does MP4050AGJ-P require an external VCC capacitor?

Yes - a minimum 1μF ceramic capacitor must be placed between VCC and GND, close to the IC. This capacitor sustains control circuitry during MOSFET conduction phases and stabilizes internal regulation. Larger values (>2.2μF) improve hold-up time during line dips but increase cost and size; 4.7μF is typical in 230VAC designs.

Can MP4050AGJ-P drive multiple parallel LED strings?

No - MP4050AGJ-P is designed for single-string constant-current operation. Driving parallel strings would cause current imbalance due to V_F mismatch, risking thermal runaway. For multi-string applications, use separate MP4050AGJ-P channels or select a multi-channel driver like MPQ4425HG-A.

What is the purpose of the PRO pin and how is it configured?

The PRO pin monitors LED string voltage during MOSFET off-time to detect open-circuit faults. It connects to the LED anode via a resistor divider (e.g., 200kΩ + 9.31kΩ) to scale voltage to 2.0V threshold. A 30pF ceramic capacitor from PRO to GND suppresses noise; time constant must remain <1μs to ensure reliable OVP response.

How does thermal foldback behave during sustained overload?

At 145°C junction temperature, MP4050AGJ-P begins linearly reducing LED current - e.g., dropping from 115mA to ~23mA at 160°C - to limit power dissipation. This preserves LED lifetime and prevents catastrophic failure. If temperature exceeds 160°C, switching halts entirely and auto-restarts only after cooling to 110°C.

Is MP4050AGJ-P suitable for dimming applications?

MP4050AGJ-P supports analog dimming via the PRO pin: applying a variable voltage (0–2.0V) modulates current foldback point, enabling 10:1 dimming range. PWM dimming is not natively supported - external FET gating of the LED string is required, with frequency >1kHz to avoid visible flicker.