Monolithic Power Systems Inc. MPQ2451DJ-LF-Z

Overview

MPQ2451DJ-LF-Z 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 current at 2MHz fixed switching frequency across a 3.3V–36V input range. It features internal soft-start, precision current limit without external sense resistor, and 130µA quiescent current-enabling use in automotive body control modules and industrial sensors requiring stable 5V or 3.3V rail generation.

For engineers reviewing the MPQ2451DJ-LF-Z datasheet, MPQ2451DJ-LF-Z pinout, MPQ2451DJ-LF-Z application, or MPQ2451DJ-LF-Z equivalent, key selection criteria include its TSOT23-6L package thermal performance (θJA = 220°C/W), 0.794V feedback reference tolerance, shutdown current ≤30µA, and compatibility with ceramic output capacitors without external compensation.

Technical Context

The MPQ2451DJ-LF-Z employs peak-current-mode control with internal transconductance error amplifier (GCS = 3A/V) and fixed 2MHz oscillator, enabling fast transient response and stable regulation under varying load conditions. Its pulse-skipping mode reduces gate-driving and switching losses at light loads, while frequency fold-back prevents inductor current runaway during startup.

It integrates a bootstrap regulator for high-side driver biasing, UVLO with 2.9V rising threshold and 0.4V hysteresis, and thermal shutdown at 150°C. The device operates across –40°C to +125°C junction temperature and supports adjustable output (0.8V to 0.9·VIN) or fixed 3.3V/5V variants via FB divider or factory-trimmed versions.

Key Specifications

Pinout & Package

MPQ2451DJ-LF-Z is packaged in a thermally enhanced TSOT23-6L (0.95mm pitch, 2.9mm × 1.6mm footprint), optimized for automotive and industrial PCBs with limited board area. The exposed pad variant improves θJA to 220°C/W on standard 4-layer boards.

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 variant trades thermal performance for smaller footprint and lower assembly cost; versus LM61480RQWR, it offers plug-and-play AEC-Q100 compliance and reduced component count at the expense of peak current capability.

Availability

MPQ2451DJ-LF-Z is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor nodes, and distributed CAN network power supplies requiring stable component supply with AEC-Q100 traceability and long-lifecycle support.

Supply support for MPQ2451DJ-LF-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 over 20 years of leadership in DC/DC conversion and motor driver technology.

The MPQ2451 belongs to MPS's automotive-grade buck converter product line, designed specifically for harsh-environment applications demanding AEC-Q100 qualification, wide input range, and minimal external components.

FAQ

What is the maximum recommended output current for MPQ2451DJ-LF-Z in TSOT23-6L at 85°C ambient?

The TSOT23-6L package has θJA = 220°C/W. At 85°C ambient and 125°C max junction temperature, allowable power dissipation is (125–85)/220 = 0.182W. With 500mΩ RDS(ON), continuous current is limited to √(0.182/0.5) ≈ 0.6A - matching the datasheet rating. Derating is required above 85°C ambient.

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

Yes. Using the formula VOUT = 0.794V × (1 + R1/R2), a 2.5V output requires R1/R2 ≈ 2.15. With R1 = 124kΩ (recommended for loop stability), R2 = 57.6kΩ yields VOUT = 2.5V ±1.5% across temperature. This configuration is validated in MPS Application Note AN042.

Does MPQ2451DJ-LF-Z require an external bootstrap diode?

No - the internal bootstrap regulator charges the BST capacitor from VIN during low-side conduction. An external diode (e.g., BAT54) is optional and only beneficial when VIN ≤ 5V and VOUT > 3.3V, or for duty cycles >65%, to improve efficiency and BST voltage stability.

How does the MPQ2451DJ-LF-Z handle short-circuit conditions?

It uses cycle-by-cycle current limiting with a 0.65–1A trip threshold. During short-circuit, the device enters hiccup mode: after ~100µs of overcurrent, it shuts down for ~10ms, then retries. This prevents thermal damage while allowing automatic recovery once fault clears - confirmed in Figure 12 of Rev 1.2 datasheet.

Is the EN pin internally pulled down when left floating?

Yes. The EN pin has an internal pull-down to GND, ensuring the device remains disabled when unconnected. This provides fail-safe behavior in systems where enable control is optional or implemented later in design revision.

What is the minimum output capacitor ESR requirement for stability?

No minimum ESR is required - the MPQ2451DJ-LF-Z is explicitly characterized for stability with zero-ESR ceramic capacitors (e.g., 10µF X5R). Its internal compensation is optimized for ceramic output caps, eliminating the need for intentional ESR addition used in older buck controllers.

Does MPQ2451DJ-LF-Z support synchronization to an external clock?

No. The oscillator is fixed-frequency and not synchronizable. For systems requiring clock alignment (e.g., multi-rail power sequencing), use the MPQ2452 series, which adds SYNC pin functionality while retaining identical pinout and electrical specs.