Monolithic Power Systems Inc. MP24875DN-LF

Overview

MP24875DN-LF from Monolithic Power Systems is a fixed-frequency, peak-current-mode step-down LED driver IC integrating a 220mΩ high-side 55V MOSFET and delivering up to 1.5A constant current for high-power LED strings. It operates from 4.5V–55V input, supports programmable switching frequency up to 200kHz via external resistor, and features 200mV reference voltage for precise current regulation-used in automotive headlight modules, industrial high-bay lighting, and outdoor signage requiring stable thermal performance.

For engineers reviewing the MP24875DN-LF datasheet, MP24875DN-LF pinout, MP24875DN-LF application, or MP24875DN-LF equivalent, key selection criteria include its 130µA quiescent current in active operation, SOIC8E package with exposed pad for thermal management, 12µA shutdown current for battery-backed systems, and internal soft-start preventing LED current overshoot during startup.

Technical Context

The MP24875DN-LF implements peak-current-mode control with a 200mV feedback reference and an error amplifier (400V/V gain, 350µA/V transconductance) driving the COMP node to regulate LED current via external sense resistor. Its programmable oscillator sets switching frequency between 150–250kHz using a resistor from FREQ to GND, enabling EMI optimization.

Thermal protection includes 150°C junction shutdown with 20°C hysteresis, while UVLO ensures operation only above 3.0V VIN (with 0.4V hysteresis). The bootstrap driver powers the high-side gate via BST–SW capacitor, with dedicated UVLO (2.2V rising threshold) and internal 4V regulation.

Key Specifications

Pinout & Package

MP24875DN-LF uses SOIC8 with exposed thermal pad (SOIC8E), where the exposed pad must be soldered to PCB ground plane for optimal thermal dissipation (θ_JA = 50°C/W, θ_JC = 10°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-power LED driver applications.

Compared with LT3474EMS#TRPBF and TPS92630QPWPRQ1, MP24875DN-LF offers superior integration (55V MOSFET + 200kHz programmability) and lowest BOM count for non-automotive industrial lighting, while trading off diagnostic features and ultra-high-frequency operation.

Availability

MP24875DN-LF is available at Aetrix Electronics and suitable for automotive headlamp modules, industrial high-bay luminaires, and outdoor digital signage requiring stable component supply across extended temperature and voltage ranges.

Supply support for MP24875DN-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, with design centers in the US, China, and Taiwan.

The MP24875 belongs to MPS's high-voltage LED driver product line, engineered specifically for efficient, thermally robust constant-current regulation in automotive and industrial lighting where input voltage variation and reliability under thermal stress are critical.

FAQ

What is the minimum input voltage required for MP24875DN-LF to start switching?

The MP24875DN-LF has a VIN UVLO rising threshold of 3.0V ±0.3V. It begins normal operation only when input voltage exceeds this level; below 2.6V, the device remains latched in shutdown regardless of EN state. This ensures stable startup under cold-cranking or low-battery conditions common in automotive applications.

Can MP24875DN-LF drive LEDs in series with total forward voltage exceeding 55V?

No. While the input voltage range is 4.5V–55V, the maximum output voltage is limited by the input minus dropout losses. With internal 220mΩ MOSFET and typical diode drop, practical output voltage is VIN − (I_LED × R_DS(on)) − V_F, so total LED string V_F must remain below VIN. For 55V input, maximum usable LED string voltage is ~52V at 1.5A.

How does the COMP pin function during startup and fault conditions?

During startup, the internal soft-start circuit overrides the error amplifier reference until the SS voltage reaches 2.6V, limiting COMP to ≤2.0V to prevent current overshoot. In shutdown (EN low or thermal fault), COMP is actively pulled to GND. Under normal operation, COMP is clamped between 0.9V and 2.0V and serves as the control voltage for peak-current limit setting.

Is an external bootstrap diode required for reliable operation?

An external bootstrap diode (e.g., BAT54) is recommended when VIN ≤ 5V, V_OUT is 3.3–5V, or when duty cycle exceeds 85%, as these conditions reduce natural BST capacitor recharge time. The diode from 5V rail to BST improves bootstrap voltage stability and prevents driver UVLO-induced reset during high-duty cycles.

What is the maximum allowable LED current ripple with standard compensation?

With typical 2.2–4.7µF ceramic output capacitance and proper CCOM1/RCOM compensation, the MP24875DN-LF achieves <10% peak-to-peak LED current ripple at 1.5A output. Ripple is further reduced by selecting inductor value to yield 30–40% inductor current ripple relative to LED current, per design equations in the datasheet.

Does MP24875DN-LF support analog dimming via the FB pin?

No. The FB pin is strictly for current-sense feedback referenced to 200mV; applying external voltage violates regulation and may cause instability. Dimming must be implemented externally via PWM signal applied to EN pin (200Hz–20kHz typical) or by modulating the sense resistor voltage using a transistor-controlled shunt path.

What thermal derating applies above +85°C ambient?

At TA = +85°C, full 1.5A output is supported if θ_JA ≤ 50°C/W and PCB thermal design maintains TJ ≤ 125°C. Above +85°C, output current must be linearly derated: I_OUT = 1.5A × (1 − (TA − 85)/40), reaching zero at TA = +125°C, per absolute maximum junction temperature of 150°C and thermal shutdown threshold.