Monolithic Power Systems Inc. MPQ3387LGRT-Z

Overview

MPQ3387LGRT-Z from Monolithic Power Systems is an AEC-Q100 Grade 1 qualified step-up white LED driver with six independent current-regulated strings, 3% inter-string current matching accuracy, 45 V max output voltage, and combined analog/PWM dimming with 25% transfer point-designed for automotive LCD backlighting requiring high reliability and low audible noise.

For engineers reviewing the MPQ3387LGRT-Z datasheet, MPQ3387LGRT-Z pinout, MPQ3387LGRT-Z application, or MPQ3387LGRT-Z equivalent, this device supports 3V–25V input, programmable 532–1250 kHz switching frequency, 24–27.5 kHz auto-shifted PWM dimming output, integrated OVP/OCP/OTP protection, and TQFN-24 (4×4 mm) thermal performance up to +125°C junction temperature.

Technical Context

The MPQ3387LGRT-Z implements peak-current-mode PWM control with dual LX outputs (LX1/LX2 internally shorted), a 5 V internal LDO (VCC) for gate drive and logic, and a dedicated ISET pin enabling precise per-string current programming via external resistor (e.g., 60.4 kΩ → 20 mA). Its feedback loop uses the lowest active LEDX pin voltage to dynamically regulate bus voltage.

Dimming mode selection is controlled by the MIX pin: high enables combined analog/PWM dimming with automatic 25% duty-cycle transfer and 100 Hz–20 kHz input → 24–27.5 kHz output frequency upshift; low enables direct PWM dimming. Protection includes recoverable OCP, OVP (programmable via resistor divider on OVP pin), open/short LED string detection, and thermal shutdown with 20°C hysteresis.

Key Specifications

Pinout & Package

TQFN-24 (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad connected to PGND. Package supports ≤2.9 W continuous power dissipation at TA = 25°C (θJA = 42°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar white LED driver applications.

Compared with MPQ3387AGRT-Z, the MPQ3387LGRT-Z adds AEC-Q100 Grade 1 qualification, enhanced test coverage, and automotive-specific failure-mode analysis; compared with LM3409QMY/NOPB, it integrates six matched current sinks, eliminates external sense resistors, and delivers superior dimming flexibility and noise performance in multi-string applications.

Availability

MPQ3387LGRT-Z is available at Aetrix Electronics and suitable for automotive instrument clusters, infotainment displays, and industrial panel PCs requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle continuity.

Supply support for MPQ3387LGRT-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, and global manufacturing partnerships.

The MPQ3387L product line targets automotive and industrial LCD backlighting applications, emphasizing AEC-Q100 qualification, multi-string current matching, low-noise dimming, and integrated protection for safety-critical display systems.

FAQ

What is the minimum input voltage required to enable the MPQ3387LGRT-Z?

The EN pin requires ≥1.5 V to activate, but the internal VCC LDO needs VIN ≥2.55 V (UVLO rising threshold) to power up control circuitry. Stable operation begins at VIN = 3 V per datasheet specification; below this, regulation is not guaranteed and startup may fail.

How does the MPQ3387LGRT-Z achieve 3% current matching between strings?

It uses six matched internal current sources with precision 1.241 V reference and low 500 mV compliance voltage, fabricated on the same die to minimize process and temperature gradients. Matching is measured as (Imax − Imin)/Iset and tested across −40°C to +125°C.

Can the MPQ3387LGRT-Z drive more than 6 LED strings?

No - it has exactly six dedicated LEDX current-sink outputs (LED1–LED6). Cascading is supported for larger displays: multiple MPQ3387LGRT-Z ICs can share one boost converter output while independently regulating their own strings.

What happens if the MIX pin is left floating?

The MIX pin has an internal weak pull-up; leaving it unconnected defaults to combined analog/PWM dimming mode with 25% transfer point. For pure PWM dimming, explicitly tie MIX to GND with ≤10 kΩ resistor.

Is the FAULT pin (Pin 21) available on all MPQ3387LGRT-Z units?

Yes - Pin 21 is designated as optional FAULT output in the TQFN-24 package. It is an open-drain signal that pulls low during OVP, OTP, or open/short LED faults; requires external pull-up resistor for proper logic level translation.

How is overvoltage protection triggered and reset?

OVP activates when the voltage on the OVP pin exceeds 1.16–1.24 V (rising edge); the IC halts switching until the pin voltage falls below the recovery threshold (~50–80 mV). Reset occurs automatically without external intervention once fault condition clears.

Does the MPQ3387LGRT-Z support analog dimming only, without PWM?

No - analog dimming is only available in combined mode (MIX = high), where it operates above 25% PWM duty cycle. There is no standalone analog dimming interface; brightness control always requires a PWM signal applied to PWMI.