Monolithic Power Systems Inc. MP38891DL-LF-P

Overview

MP38891DL-LF-P from Monolithic Power Systems is a synchronous step-down DC/DC converter with integrated 50mΩ high-side MOSFET and external gate driver for low-side FET control. It delivers 6A continuous output current across 4.5V–30V input, supports fixed 420kHz or synchronizable up to 1.4MHz operation, and regulates output from 0.8V to 15V-used in flat-panel TV power rails requiring high efficiency and thermal robustness.

For engineers reviewing the MP38891DL-LF-P datasheet, MP38891DL-LF-P pinout, MP38891DL-LF-P application, or MP38891DL-LF-P equivalent, key selection criteria include its synchronizable gate driver capability, cycle-by-cycle overcurrent protection, thermal shutdown at 150°C, compatibility with low-ESR ceramic output capacitors, and 3mm × 4mm QFN14 package for space-constrained industrial power designs.

Technical Context

The MP38891DL-LF-P implements peak-current-mode control with a fixed 420kHz internal oscillator, extendable to 1.4MHz via EN/SYNC pin synchronization. Its error amplifier compares FB voltage against a 0.808V internal reference and drives COMP to regulate duty cycle through PWM comparator and current-sense amplifier.

It integrates a 5V internal VCC regulator (with 4.5V–5.0V output under 5mA load), bootstrap circuitry for floating gate drive, and hiccup-mode recovery during output short-circuit events. The BG driver provides source/sink impedances of 4Ω/1Ω and senses switch current via 20mV threshold on SW node.

Key Specifications

Pinout & Package

MP38891DL-LF-P is housed in a thermally enhanced 3mm × 4mm 14-pin QFN package with exposed thermal pad. Pin 1 is marked by a dot; the exposed pad must be soldered to PCB ground for optimal thermal performance (θ_JA = 45°C/W, θ_JC = 10°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP38891DL-LF-P, MPQ38891-AEC1 adds automotive qualification but shares identical electrical specs and pinout, while MP2386DL-LF-Z sacrifices gate driver flexibility and current capability for integration simplicity and lower BOM count.

Availability

MP38891DL-LF-P is available at Aetrix Electronics and suitable for flat panel television power rails, digital set-top box core supplies, and broadband communications gateway designs requiring stable component supply, RoHS-compliant packaging, and long-term industrial lifecycle support.

Supply support for MP38891DL-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 mixed-signal ICs for power management, motion control, and interface applications.

The MP38891 belongs to MPS's high-current synchronous buck controller product line, designed specifically for space-constrained, thermally demanding industrial and consumer power systems requiring programmable output voltage and multi-rail synchronization.

FAQ

What is the minimum recommended input capacitance for MP38891DL-LF-P?

A 22µF X5R/X7R ceramic capacitor is recommended at the IN pins to handle high-frequency switching ripple. For optimal performance, place it within 3mm of pins 4–6 and use parallel 0.1µF ceramic for high-frequency decoupling. RMS current rating should exceed 3A based on worst-case VIN=2×VOUT condition.

Can MP38891DL-LF-P operate without an external synchronous MOSFET?

No. MP38891DL-LF-P requires an external low-side MOSFET driven by the BG pin. It does not integrate a second power switch. Omitting the external FET prevents proper inductor freewheeling and will cause immediate failure due to shoot-through or excessive voltage stress on the internal high-side switch.

How is output voltage adjusted on MP38891DL-LF-P?

Output voltage is set using a resistor divider between VOUT and GND, with the FB pin connected to the midpoint. With a standard 40.2kΩ top resistor (R1), R2 is calculated as R2 = 0.8 × R1 / (VOUT − 0.8). For example, 3.3V output uses R2 = 13kΩ, yielding 0.808V feedback reference at FB.

What thermal derating applies above 85°C ambient?

At TA = +85°C, maximum continuous output current drops to ~4.8A due to thermal limits. Derating follows PD(MAX) = (150°C − TA)/45°C/W. At TA = +100°C, max power dissipation falls to 1.11W, limiting practical output to ~3.5A with adequate copper pour and airflow.

Is an external bootstrap diode required for MP38891DL-LF-P?

An external bootstrap diode (e.g., IN4148) is optional and recommended only when VOUT = 3.3V or 5V and duty cycle exceeds 65% (i.e., VIN > 7.7V for 3.3V out). It improves BST capacitor charging efficiency and reduces gate drive losses under high-duty-cycle conditions.

Does MP38891DL-LF-P support forced PWM mode at light load?

No. MP38891DL-LF-P operates exclusively in peak-current-mode PWM and does not include pulse-skipping or forced continuous conduction mode (FCCM) control. Light-load efficiency relies on reduced switching losses and low quiescent current (0.9mA), not mode switching.

What is the purpose of the N/C pin (Pin 7)?

Pin 7 is a no-connect terminal with no internal bond wire. It must remain unconnected on the PCB-neither routed nor stubbed-to avoid parasitic coupling or mechanical stress on the die. Leaving it floating ensures signal integrity and thermal reliability.