Monolithic Power Systems Inc. MP2309DS-LF

Overview

MP2309DS-LF from Monolithic Power Systems is a monolithic synchronous buck regulator integrating 140mΩ high- and low-side N-channel MOSFETs, delivering 1A continuous output current across a 4.75V–23V input range. It features fixed 340kHz switching frequency, adjustable 0.923V–20V output via resistive feedback, cycle-by-cycle overcurrent protection, and 1μA shutdown quiescent current - deployed in FPGA/DSP power supplies and notebook DC-DC conversion.

For engineers reviewing the MP2309DS-LF datasheet, MP2309DS-LF pinout, MP2309DS-LF application, or MP2309DS-LF equivalent, key selection criteria include input voltage range compatibility, integrated MOSFET R_DS(ON), soft-start programmability, thermal shutdown threshold (160°C), and SOIC8 package suitability for space-constrained PCB layouts.

Technical Context

The MP2309DS-LF implements current-mode control with an internal transconductance error amplifier (G_EA = 800 μA/V) and COMP-pin-based loop compensation. Its functional block includes a 340kHz oscillator, 0.923V precision feedback reference, and dual comparators for overvoltage (1.1V trip), UVLO (4.1V rising threshold), and EN lockout (2.5V).

It uses bootstrap gate drive architecture requiring a capacitor between SW and BS pins to elevate the high-side gate voltage above VIN. The device supports external Schottky diode paralleling for efficiency improvement under high-duty-cycle conditions and enables stable regulation with low-ESR ceramic output capacitors down to 22μF.

Key Specifications

Pinout & Package

MP2309DS-LF is housed in an 8-pin SOIC package (JEDEC MS-012AC, 3.9mm × 4.9mm × 1.75mm height) with exposed pad not electrically connected. Thermal resistance θ_JA = 90°C/W on 4-layer PCB per JESD51-7.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2307DN-LF and TPS561201, MP2309DS-LF uniquely supports 23V input with matched 140mΩ MOSFETs in SOIC8, offering optimal balance of voltage range, thermal performance, and external component flexibility for mid-power industrial and computing rails.

Availability

MP2309DS-LF is available at Aetrix Electronics and suitable for FPGA power supplies, notebook subsystem regulation, and green appliance MCU power management requiring stable component supply, long-term lifecycle support, and RoHS-compliant lead-free packaging.

Supply support for MP2309DS-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 power ICs, headquartered in Kirkland, WA, with global design and support operations.

The MP2300 series targets cost-sensitive, space-constrained DC-DC conversion in computing, communications, and consumer electronics - emphasizing integration, efficiency, and ease of use without external gate drivers or compensation components.

FAQ

What is the minimum recommended output capacitor for stable operation?

The MP2309DS-LF is optimized for ceramic output capacitors starting at 22μF/6.3V (e.g., 22μF X5R). Lower values may cause instability or excessive ripple; the datasheet validates stability with 22μF and specifies ESR <10mΩ for best transient response and phase margin.

Can MP2309DS-LF operate with input voltage below 4.75V?

No - the absolute minimum operating input is 4.75V per datasheet specifications. Input below 3.80V triggers UVLO shutdown, and operation between 3.80V–4.75V is undefined and unsupported. For sub-4.75V inputs, consider MPS MP2101 or MP2143.

Is an external bootstrap diode required for all applications?

An external Schottky diode (e.g., IN4148) from VOUT to BS is optional but recommended when duty cycle exceeds 65% - such as in 5V or 3.3V outputs from 12V input. It improves high-side gate drive efficiency and reduces thermal stress on the internal charge pump.

How does the COMP pin compensation affect loop stability?

The COMP pin connects to the error amplifier output; its RC network (e.g., 7.5kΩ + 3.3nF) sets a dominant pole-zero pair to achieve ≥45° phase margin. Incorrect values cause oscillation or sluggish load response - compensation must be tuned per inductor value, output cap ESR, and target crossover frequency (<34kHz).

What is the maximum achievable output voltage?

The MP2309DS-LF supports up to 20V output, limited by internal OVP threshold (1.1V at FB corresponds to ~20V with R1/R2 divider). Beyond this, the OVP circuit discharges COMP and SS, forcing shutdown - preventing damage during feedback resistor miscalculation or fault conditions.

Does MP2309DS-LF support forced PWM or PFM mode selection?

No - it operates exclusively in forced continuous conduction mode (CCM) with fixed 340kHz frequency. There is no pulse-frequency modulation (PFM) or skip-cycle mode; light-load efficiency relies on low 1.5mA quiescent current and 1μA shutdown state.

What is the purpose of the SS pin's 6μA constant current source?

The SS pin integrates a 6μA current source that linearly charges an external capacitor to generate a controlled voltage ramp. This ramp modulates the internal current limit, producing smooth output voltage rise and limiting inrush current into output capacitance during startup.