Monolithic Power Systems Inc. MP3373GM-P

Overview

MP3373GM-P from Monolithic Power Systems is an 8-channel step-up WLED controller with external transistor drive, designed for large LCD panel backlighting. It operates from 9V–40V input, delivers 1.2% current matching across strings, supports programmable 100kHz–1MHz switching frequency via ROSC, and integrates phase-shift PWM dimming to suppress inrush current in TV/monitor backlight systems.

For engineers reviewing the MP3373GM-P datasheet, MP3373GM-P pinout, MP3373GM-P application, or MP3373GM-P equivalent, key selection criteria include its 8-channel external current sink architecture, 200mV FB regulation voltage, CTLx-based transistor control interface, OVP/short/open LED protection scheme, and TSSOP-28 package thermal performance (θJA = 80°C/W).

Technical Context

The MP3373GM-P implements peak-current-mode, fixed-frequency boost control with internal 10V LDO (VCC) powering gate driver and logic. Its 8 independent CTLx/FBx pairs regulate external NPN/PNP transistors per string, using 200mV reference feedback and 1.2% inter-string current matching.

Protection is hardware-asserted: OVP triggers at 2.5V (latch-off at 3.0V), CTLx UVLO disables strings below 205mV, thermal shutdown activates at 150°C (25°C hysteresis), and FAULT pin provides open-drain fault signaling. Phase shift is auto-adjusted (45°/60°/90°) based on active string count when PSEN floats.

Key Specifications

Pinout & Package

MP3373GM-P is housed in a thermally enhanced TSSOP-28 package (4.4mm × 9.7mm, 0.65mm pitch) with exposed thermal pad for PCB heat dissipation. Pin 1 is VIN; pin 28 is PSEN; FAULT (pin 23) is open-drain; GATE (pin 27) drives external N-MOSFET; and pins 7–22 provide mirrored FBx/CTLx pairs for all 8 strings.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar WLED controller applications.

Compared with MP3372GM-Z and LM3409QMH/NOPB, MP3373GM-P uniquely delivers 8-channel matched current regulation with auto-phase-shift and per-string hardware protection-enabling higher integration, lower EMI, and greater reliability in large-panel backlighting without added ICs or firmware.

Availability

MP3373GM-P is available at Aetrix Electronics and suitable for LCD TV backlighting, commercial monitor design, digital signage, and medical imaging displays requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3373GM-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 MP3373 product line targets large-format LCD backlighting applications, delivering high-efficiency, multi-string WLED control with integrated protection and flexible dimming to replace discrete solutions in TV, monitor, and signage markets.

FAQ

What is the function of the PSEN pin on MP3373GM-P?

The PSEN pin enables or disables the automatic phase-shift PWM dimming function. When left floating, it activates phase-shift timing (45°/60°/90° between strings) to reduce input ripple and audible noise. Pulling PSEN to GND disables phase shift, synchronizing all 8 strings to the same PWM edge-useful for applications requiring simultaneous string activation.

How does MP3373GM-P handle open LED string faults?

MP3373GM-P detects open strings by monitoring CTLx pin voltage. If CTLx falls below 205mV (UVLO threshold), the IC marks that string as inactive, stops regulating its current, and continues operation with remaining strings. The FAULT pin asserts low, and the output bus voltage is regulated by the highest-voltage active string.

Can MP3373GM-P drive MOSFETs directly, or is it limited to bipolar transistors?

MP3373GM-P's CTLx pins are designed to sink up to 10mA and interface with the base of NPN transistors or gate of logic-level N-MOSFETs. While optimized for bipolar external switches, it can drive small-signal MOSFETs with appropriate gate-resistor sizing-but discrete NPN/PNP is recommended for high-current, high-reliability backlight applications.

What is the minimum on-time limitation, and why does it matter?

The MP3373GM-P has a 200ns minimum on-time for the GATE driver. This limits the maximum achievable duty cycle at high input voltages (e.g., VIN ≈ VOUT), constraining boost ratio in high-VIN applications. It also defines the lowest practical switching frequency for stable light-load operation in pulse-skipping mode.

How is LED current set, and what determines accuracy?

LED current is set by the FBx pin's 200mV reference voltage applied across an external sense resistor (e.g., 2Ω → 100mA). Accuracy depends on FBx voltage tolerance (±7mV), resistor tolerance, transistor β variation, and PCB layout symmetry-achieving 1.2% matching between strings under matched thermal and routing conditions.

Does MP3373GM-P support analog and PWM dimming simultaneously?

No-MP3373GM-P supports either analog dimming (via 0.4–1.5V DC on DIM pin) or PWM dimming (via EN/PWM or DIM pin), but not both concurrently. Using analog dimming eliminates PWM-related flicker; PWM dimming offers higher contrast ratio and better low-brightness linearity.

What thermal derating applies to the TSSOP-28 package at 85°C ambient?

With θJA = 80°C/W, the MP3373GM-P's maximum allowable power dissipation at 85°C ambient is (150°C – 85°C) / 80°C/W = 0.81W. This corresponds to ~52% of its 1.56W rated PD at 25°C, requiring careful layout and thermal vias under the exposed pad for sustained full-load operation.