Monolithic Power Systems Inc. MP2481DH-LF-Z

Overview

MP2481DH-LF-Z from Monolithic Power Systems is a 36V, 1.2A white LED driver IC supporting both buck and buck-boost topologies, featuring fixed 1.4MHz switching frequency, integrated 0.30Ω MOSFET, 0.2V feedback reference, and combined EN/DIM control pin for analog and PWM dimming. It delivers up to 95% efficiency in LCD backlight and automotive interior lighting applications.

For engineers reviewing the MP2481DH-LF-Z datasheet, MP2481DH-LF-Z pinout, MP2481DH-LF-Z application, or MP2481DH-LF-Z equivalent, this page provides verified technical context, validated pin functions, confirmed operating conditions (4.5–36V input, –40°C to +125°C), real-world efficiency curves, and alternative selection guidance grounded in functional equivalence and package compatibility.

Technical Context

The MP2481DH-LF-Z implements current-mode control with internal slope compensation and a 1.4MHz oscillator (fold-back to 120kHz under OVP fault), enabling fast transient response and stable loop behavior across wide input and load ranges. Its dual-mode operation supports step-down (VIN > VOUT) and inverting step-up/down (VIN < |VOUT|) configurations without external mode-select logic.

It integrates protection features including cycle-by-cycle current limiting (2.0A typical limit), thermal shutdown (150°C), open-string detection via OVP pin threshold (1.23V), input overvoltage lockout (3.4V rising threshold), and output short-circuit protection - all implemented with dedicated internal comparators and latched shutdown logic.

Key Specifications

Pinout & Package

MP2481DH-LF-Z is housed in an 8-pin MSOP-EP (MSOP8E) package with exposed thermal pad on the underside, requiring solder connection to PCB ground plane for optimal thermal performance. Pin 1 is marked with half-circle indentation per JEDEC MO-187 AA-T.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar white LED driver applications.

Compared with MPQ2481DQ-LF-Z, the MP2481DH-LF-Z trades automotive qualification for lower unit cost and identical core functionality; versus LM3409HVMM/NOPB, it delivers faster time-to-market via full integration but less configurability in frequency and protection thresholds.

Availability

MP2481DH-LF-Z is available at Aetrix Electronics and suitable for LCD backlight panels, automotive interior lighting, and handheld computer illumination requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.

Supply support for MP2481DH-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 design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP2481 belongs to MPS's white LED driver product line, engineered specifically for space-constrained, high-reliability lighting applications demanding integrated protection, multi-topology flexibility, and minimal external components.

FAQ

What is the maximum LED string voltage the MP2481DH-LF-Z can drive in buck-boost mode?

In buck-boost (inverting) configuration, the MP2481DH-LF-Z supports output voltages up to |VOUT| = VIN × (D/(1−D)), where duty cycle D is limited to 89%. With 36V input and 89% max duty, theoretical |VOUT| reaches ~285V; however, practical limits are set by external components - Schottky diode reverse voltage rating and output capacitor voltage rating - not the IC itself.

Can the MP2481DH-LF-Z operate with only one LED in the string?

Yes. The MP2481DH-LF-Z has no minimum LED requirement due to its current-mode architecture and open-string protection logic. It regulates current accurately even with a single LED or zero LEDs (open condition), triggering OVP shutdown only when V_OVP exceeds 1.23V - making it ideal for modular lighting designs with variable string counts.

How does the EN/DIM pin handle simultaneous enable and dimming commands?

The EN/DIM pin uses a single analog voltage level to control both functions: below 0.4V disables the IC; between 0.7V and 1.4V sets analog dimming current linearly from 0% to 100%; above 1.4V enables full current and accepts PWM signals. Internal circuitry separates enable state from dimming modulation, eliminating need for external logic.

What is the purpose of the separate INGND pin, and why must it not connect to VSS in buck-boost mode?

The INGND pin serves as the reference for the EN/DIM signal and enables proper biasing in inverting buck-boost configurations where VSS is at negative potential relative to input ground. Connecting INGND to VSS in such cases would short the internal reference, disabling dimming control and potentially damaging the EN/DIM comparator - hence the strict separation requirement.

Does the MP2481DH-LF-Z require an external bootstrap diode?

No. The MP2481DH-LF-Z integrates bootstrap charging circuitry and only requires a 10nF ceramic capacitor between BST and SW pins. An external diode is unnecessary - unlike discrete gate drivers - because internal charge pump and level-shifting logic manage high-side FET gate drive autonomously.

How does the OVP pin function differ between normal operation and fault condition?

During normal operation, the OVP pin monitors output voltage via a resistor divider; its voltage is held between 0.4V and 1.23V. If voltage drops below 0.4V, the oscillator folds back to 120kHz to reduce stress; if it rises to 1.23V, the IC shuts down the switch and enters latch-off mode until input conditions normalize - providing dual-level overvoltage defense.

What PCB layout practices are critical for achieving 95% efficiency?

To achieve ≥95% efficiency, place the 4.7µF input capacitor within 2mm of VDD/VSS pins using wide copper pours; route SW with ≥0.5mm trace width and minimize loop area with inductor and Schottky diode; connect the exposed thermal pad to a solid inner-layer ground plane with ≥4 thermal vias; and isolate FB traces from noisy nodes using guard rings.