Monolithic Power Systems Inc. MP2403DN-LF

Overview

MP2403DN-LF from Monolithic Power Systems is a monolithic synchronous step-down DC/DC converter integrating 150mΩ high-side and 80mΩ low-side MOSFETs, delivering 3A continuous output current across 4.6V–32V input range with fixed 250kHz switching frequency and 0.80V feedback reference. It regulates down to 0.80V output voltage and supports notebook computers and distributed power systems.

For engineers reviewing the MP2403DN-LF datasheet, MP2403DN-LF pinout, MP2403DN-LF application, or MP2403DN-LF equivalent, key selection criteria include input UVLO threshold (3.95V), thermal shutdown (160°C), soft-start programmability via external capacitor, cycle-by-cycle overcurrent protection, and compatibility with low-ESR ceramic output capacitors.

Technical Context

The MP2403DN-LF employs current-mode control architecture with internal transconductance error amplifier (820μA/V) and ramp-based PWM comparator for fast transient response and inherent cycle-by-cycle current limiting. Its integrated high- and low-side N-channel MOSFETs eliminate external switch requirements while enabling up to 95% efficiency at 3.3V/3A output.

Operation relies on bootstrap capacitor coupling between SW and BS pins to drive the high-side gate above VIN; the 0.80V precision feedback reference enables accurate output regulation across temperature (±0.035V variation from –40°C to +85°C), and EN pin provides digital enable/disable with 1.3V typical turn-on threshold and 205mV hysteresis.

Key Specifications

Pinout & Package

MP2403DN-LF uses an 8-pin SOIC package with exposed thermal pad (SOIC8N), requiring direct connection of the exposed pad and Pin 4 (GND) to a common ground plane for thermal performance and electrical stability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2403DN-LF, MP2451DT-LF-Z trades thermal performance and current capability for compactness, while LM2678SD-ADJ/NOPB sacrifices integration and efficiency for higher peak current and legacy design familiarity.

Availability

MP2403DN-LF is available at Aetrix Electronics and suitable for industrial distributed power, notebook computer core supply, and automotive body control module applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for MP2403DN-LF 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, with global design centers and manufacturing partnerships.

The MP2403 belongs to MPS's integrated synchronous buck converter product line, designed specifically for compact, high-efficiency DC/DC conversion in space- and thermal-constrained applications from 4.6V to 32V input.

FAQ

What is the minimum input voltage required for reliable startup?

The MP2403DN-LF features an input under-voltage lockout (UVLO) with a rising threshold of 3.95V ±0.35V at +25°C. Startup is guaranteed only when VIN exceeds this threshold; operation below 4.6V may result in unstable regulation or shutdown. The 125mV hysteresis prevents oscillation during marginal input conditions.

Can the MP2403DN-LF operate with ceramic output capacitors only?

Yes - the MP2403DN-LF is explicitly characterized for stability with low-ESR ceramic output capacitors, including X5R and X7R dielectrics. Typical designs use 22μF–100μF ceramic arrays; compensation values in Table 3 of the datasheet are optimized for these configurations without requiring additional ESR.

How is thermal performance affected by the exposed pad connection?

The exposed pad in the SOIC8N package must be soldered to a dedicated thermal copper plane connected to Pin 4 (GND). Without this connection, θ_JA degrades from 50°C/W to >80°C/W, causing junction temperature to exceed 125°C at 3A load and triggering thermal shutdown. Minimum recommended solder area is 10.7mm².

What happens during output short-circuit condition?

Under short-circuit, the MP2403DN-LF enters frequency foldback mode, reducing switching frequency from 250kHz to ~55kHz to limit power dissipation. Cycle-by-cycle current limiting caps peak switch current at ~4.8A, and thermal shutdown activates if junction temperature reaches 160°C - ensuring safe, self-protecting behavior.

Is an external bootstrap diode required for standard operation?

No - the internal charge pump suffices for most applications. An external Schottky diode (e.g., IN4148) from VOUT to BS is optional and recommended only when VOUT is 3.3V or 5V *and* duty cycle exceeds 65% (i.e., VIN > 7.7V for 3.3V output), to improve high-duty-cycle efficiency by reducing bootstrap capacitor discharge.

What is the maximum achievable output voltage?

The MP2403DN-LF supports output voltages up to 28V, set by the feedback divider ratio. However, practical limits arise from the 35V absolute maximum input rating and internal 5V bias rail - outputs above 12V require careful attention to voltage stress on external components and PCB creepage/clearance.

Does the COMP pin require external components for basic operation?

Yes - the COMP pin is the error amplifier output and must be compensated with at least a series RC network to GND. Omitting compensation causes instability and oscillation. Table 3 in the datasheet provides validated R3/C3 values for common output voltages and capacitor types; C6 is added only when output capacitor ESR introduces a destabilizing zero.