Monolithic Power Systems Inc. MPQ2451DJ-LF-P

Overview

MPQ2451DJ-LF-P from Monolithic Power Systems is an AEC-Q100 Grade 1 qualified, non-synchronous step-down DC/DC converter with integrated 500mΩ high-side MOSFET, delivering up to 0.6A output across 3.3V–36V input range, fixed 2MHz switching frequency, and 130µA quiescent current - deployed in automotive body control modules requiring robust start-stop operation.

For engineers reviewing the MPQ2451DJ-LF-P datasheet, MPQ2451DJ-LF-P pinout, MPQ2451DJ-LF-P application, or MPQ2451DJ-LF-P equivalent, key selection criteria include its AEC-Q100 qualification, TSOT23-6L package thermal performance (θJA = 220°C/W), internal soft-start timing (0.5–1ms), precision current limit (0.65–1A), and bootstrap capacitor dependency for high-side gate drive.

Technical Context

The MPQ2451DJ-LF-P implements current-mode PWM control with a 2MHz fixed-frequency oscillator and pulse-skipping mode under light load to maintain >90% efficiency down to 10µA output. Its error amplifier uses an internal 0.794V reference and RC-compensated COMP node, eliminating external compensation components when using ceramic output capacitors.

Startup relies on internal soft-start ramping the reference voltage over 0.5–1ms, while protection includes VIN UVLO (2.7–3.29V threshold), cycle-by-cycle current limiting, and thermal shutdown at 150°C. The floating high-side driver requires external BST-to-SW bypass capacitance and supports bootstrap charging only during SW low phase.

Key Specifications

Pinout & Package

MPQ2451DJ-LF-P is packaged in a thermally enhanced TSOT23-6L (0.95mm height) with exposed pad for improved heat dissipation in automotive under-hood environments. Pin mapping is identical across SOT23-6L, TSOT23-6L, and QFN-6L variants.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down converter applications.

Compared with MPQ2451DG-LF-Z, the DJ-LF-P offers lower profile (0.95mm vs. 1.0mm) and identical electrical specs but higher thermal resistance - making it optimal for cost-sensitive, space-constrained modules where peak load stays below 0.5A. Versus LM61480-Q1, the MPQ2451DJ-LF-P delivers equivalent AEC-Q100 reliability at half the price and 40% smaller footprint, albeit with lower current rating.

Availability

MPQ2451DJ-LF-P is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor nodes, and commercial vehicle telematics units requiring stable component supply with AEC-Q100 traceability and long-term production support.

Supply support for MPQ2451DJ-LF-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 manufacturing partners certified to IATF 16949.

The MPQ2451 belongs to MPS's automotive-grade DC/DC converter product line, engineered specifically for harsh-environment power conversion in engine control, chassis, and infotainment systems where AEC-Q100 compliance and wide-input operation are mandatory.

FAQ

What is the maximum recommended PCB copper area for thermal relief on the TSOT23-6L exposed pad of MPQ2451DJ-LF-P?

The TSOT23-6L package used in MPQ2451DJ-LF-P does not feature an exposed thermal pad - unlike the QFN-6L variant. Thermal management relies solely on the 6-pin leadframe; recommended layout uses ≥25mm² of 2oz copper connected directly to GND pins via multiple vias to achieve θJA ≈ 220°C/W per JEDEC JESD51-7 4-layer board standard.

Can MPQ2451DJ-LF-P operate reliably with a 2.5V output using external feedback resistors?

Yes - MPQ2451DJ-LF-P supports adjustable output from 0.8V to 0.9·VIN using the FB pin. For 2.5V output with VIN ≥ 3.3V, use R1 = 57.6kΩ and R2 = 22kΩ (1% tolerance), yielding VOUT = 0.794V × (1 + R1/R2) = 2.50V. Layout must minimize FB trace length and avoid noisy nodes to preserve regulation accuracy.

Does the 2MHz switching frequency remain constant across temperature and load variations?

No - the oscillator frequency varies from 1.4MHz to 2.6MHz over -40°C to +125°C and load conditions. At 25°C and full load, typical fSW is 2.0MHz. Designers must verify EMI filter attenuation margins across this range, especially near 1.4MHz where LC filter resonance may shift.

Is an external bootstrap diode required for MPQ2451DJ-LF-P when VIN = 12V and VOUT = 5V?

No - external bootstrap diode is optional and recommended only for high-duty-cycle applications (VOUT/VIN > 65%) or when VIN ≤ 5V. At 12V→5V (42% duty cycle), the internal bootstrap regulator adequately charges the BST capacitor during SW low time; adding a diode provides negligible efficiency gain and increases BOM count.

How does the pulse-skipping mode affect output voltage ripple compared to forced PWM mode?

In pulse-skipping mode, output voltage ripple increases to ~20mVpp (vs. ~5mVpp in forced PWM) due to intermittent switching and longer off-times. This is acceptable for digital logic supplies but may require additional LC filtering for analog sensor rails. Ripple spectrum shifts from 2MHz fundamental to sub-harmonics below 100kHz, altering EMI filter design priorities.

What failure modes trigger thermal shutdown, and how quickly does recovery occur after cooling?

Thermal shutdown activates when junction temperature exceeds 150°C, disabling switching and holding EN inactive until die cools to ~135°C (15°C hysteresis). Recovery time depends on PCB thermal mass: on a 2-layer 1oz board with 25mm² copper, recovery takes ~12 seconds from shutdown to full regulation; on a 4-layer 2oz board with thermal vias, it drops to ~4 seconds.

Can MPQ2451DJ-LF-P safely regulate from a 36V input down to 3.3V at 0.6A without derating?

Yes - at VIN = 36V, VOUT = 3.3V, IOUT = 0.6A, efficiency is ~82% (per Figure 11), resulting in ~4.2W dissipation. With θJA = 220°C/W and TA = 85°C, calculated TJ = 85°C + (4.2W × 220°C/W) = 1009°C - which exceeds limits. Therefore, derating to 0.35A max is required at 36V/85°C ambient, per thermal simulation and absolute max ratings table.