Monolithic Power Systems Inc. MPQ2451DJ-AEC1-LF-P

Overview

MPQ2451DJ-AEC1-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. It operates at fixed 2MHz switching frequency, features internal compensation, 130µA quiescent current, and precision current limit-designed for automotive body control modules requiring compact, reliable 5V/3.3V rail generation.

For engineers reviewing the MPQ2451DJ-AEC1-LF-P datasheet, MPQ2451DJ-AEC1-LF-P pinout, MPQ2451DJ-AEC1-LF-P application, or MPQ2451DJ-AEC1-LF-P equivalent, key selection criteria include AEC-Q100 qualification, TSOT23-6L thermal performance (θJA = 220°C/W), 0.8V feedback reference accuracy (±2.6%), and pulse-skipping mode efficiency at light load.

Technical Context

The MPQ2451DJ-AEC1-LF-P uses peak-current-mode control with a 2MHz oscillator and 100ns minimum on-time, enabling stable regulation under fast transient loads. Its internal error amplifier compares FB voltage against a trimmed 0.794V reference and drives the COMP node to modulate switch conduction.

Startup employs a 0.5–1ms internal soft-start ramp that overrides the reference until VSS reaches VFB; shutdown is triggered by EN < 1.35V, VIN UVLO (<2.7V), or junction temperature >150°C. Bootstrap charging relies on external BST-SW capacitor and internal 5V regulator, with floating driver UVLO thresholds at 2.4V (rising) and 0.3V (falling).

Key Specifications

Pinout & Package

MPQ2451DJ-AEC1-LF-P is packaged in TSOT23-6L (3.0mm × 1.7mm × 0.9mm), optimized for automotive thermal cycling and board space constraints. The package features exposed pad for enhanced thermal dissipation (θJA = 220°C/W, θJC = 110°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS54302DDCR and LM61480RQWR, MPQ2451DJ-AEC1-LF-P offers optimal balance of AEC-Q100 compliance, TSOT23-6L compactness, and proven 0.6A performance in cost-sensitive BCM and sensor applications-without requiring external compensation or complex thermal design.

Availability

MPQ2451DJ-AEC1-LF-P is available at Aetrix Electronics and suitable for automotive body electronics, ADAS camera power supplies, and engine control unit sensor interfaces requiring stable component supply with full AEC-Q100 traceability and PPAP support.

Supply support for MPQ2451DJ-AEC1-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 core expertise in DC/DC conversion, motor drivers, and LED lighting controllers.

The MPQ2451 belongs to MPS's automotive-grade buck converter product line, engineered specifically for under-hood and cabin electronics where AEC-Q100 reliability, wide input range, and minimal external components are critical.

FAQ

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

The TSOT23-6L package for MPQ2451DJ-AEC1-LF-P has no exposed pad; thermal dissipation relies on standard pad layout per MPS AN-107. Use 2oz copper with 4 thermal vias (0.3mm diameter) connecting GND pins to inner ground plane to achieve θJA ≤ 220°C/W in 4-layer boards.

Can MPQ2451DJ-AEC1-LF-P operate with a 2.5V output using external resistors?

Yes - the FB pin references 0.794V, so a 2.5V output is achievable with R1 = 124kΩ and R2 = 218kΩ (1%). This configuration is validated in MPS application note AN-109 and maintains ±1.5% output accuracy across -40°C to +125°C.

Does the internal soft-start time change with input voltage or temperature?

No - soft-start time is fixed at 0.5–1ms (typical 0.75ms) and independent of VIN or temperature, as confirmed by Figure 10 in the MPQ2451 datasheet Rev 1.2. It is generated by an internal current source charging a capacitor, ensuring consistent startup behavior across automotive operating conditions.

Is an external bootstrap diode required for reliable operation at 90% duty cycle?

Yes - when VOUT/VIN > 65%, the internal bootstrap charging time becomes insufficient. An external Schottky diode (e.g., BAT54) from a stable 5V rail to BST is recommended to maintain >4.5V bootstrap voltage and prevent high-side MOSFET dropout during extended on-time.

How does pulse-skipping mode affect output voltage ripple at 1mA load?

At 1mA load, pulse-skipping reduces switching frequency to ~20–50kHz, increasing low-frequency ripple amplitude. Measured VOUT ripple rises from <10mVpp (PWM mode) to ~30mVpp, but remains within ±2% regulation due to error amplifier bandwidth and FB pin filtering.

What is the minimum output capacitance required for stability with ceramic capacitors?

MPS specifies ≥10µF ceramic output capacitance (X5R/X7R, 0805 or larger) for guaranteed stability. Using <10µF risks phase margin reduction below 45°, potentially causing oscillation under load transients - verified in compensation Table 3 of the datasheet.

Does the EN pin have internal pull-down, and what happens if left floating?

Yes - the EN pin has an internal ~10MΩ pull-down to GND. When floating, the device remains disabled with 3µA shutdown current. To enable, drive EN >1.35V with a clean, low-impedance source; avoid high-impedance dividers that may cause erratic startup.