Monolithic Power Systems Inc. MP4008GS

Overview

MP4008GS from Monolithic Power Systems is a current-mode WLED controller IC for high-brightness LED backlighting and illumination systems, operating from 9V–28V input, regulating LED current via external MOSFET with 280mV ±1.8% feedback voltage, fixed 180kHz switching frequency, and fast PWM dimming support up to 10,000:1 ratio in boost or SEPIC topologies.

For engineers reviewing the MP4008GS datasheet, MP4008GS pinout, MP4008GS application, or MP4008GS equivalent, this device is selected for precision constant-current LED driver designs requiring thermal shutdown, short-LED protection, OVP programmability via OVP pin, cycle-by-cycle current limiting, and SOIC-8 layout compatibility in space-constrained industrial and automotive lighting modules.

Technical Context

The MP4008GS implements peak-current-mode control with integrated slope compensation to prevent sub-harmonic oscillation at duty cycles >50%, using an internal error amplifier (GEA = 440 µA/V) and COMP pin-based RC compensation network for loop stability in boost/SEPIC configurations driving strings up to 70V output.

It integrates dual-protection logic: latch-off fault detection for short-LED (FB >580mV for 1µs), short-circuit (OVP <280mV & FB <0.3×REF & COMP >1V), and over-current (CS >535mV for 7 consecutive cycles within 300ns blanking window), all pulling GATE and COMP low to halt switching.

Key Specifications

Pinout & Package

MP4008GS is housed in a standard SOIC-8 package (5.0 mm × 6.0 mm, 1.27 mm pitch), thermally optimized with θ_JA = 96°C/W on 4-layer PCB, suitable for reflow assembly and industrial temperature operation (–40°C to +125°C junction).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM3409MM/NOPB and MAX16832AASA+, MP4008GS provides superior fault coverage (latch-off short-LED/OVP), built-in slope compensation for stable high-duty boost, and direct OVP programming-making it optimal for industrial and automotive LED systems demanding reliability and design simplicity.

Availability

MP4008GS is available at Aetrix Electronics and suitable for LCD backlighting, automotive interior lighting, industrial machine vision illumination, and architectural accent lighting requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.

Supply support for MP4008GS 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 distribution through authorized partners.

The MP4008 belongs to MPS's WLED controller product line, engineered specifically for high-current, high-accuracy LED driving in industrial, automotive, and display applications where thermal resilience, fault robustness, and layout simplicity are critical.

FAQ

What is the recommended inductor value for a 350mA, 70V LED string with 12V input?

For 12V input, 70V output, and 350mA LED current, use a 100 µH shielded power inductor rated ≥1.2A saturation current. Design for 30–60% inductor ripple (ΔI_L ≈ 105–210mA) in continuous conduction mode; ensure DCR <150 mΩ to minimize conduction loss and thermal rise.

How does the MP4008GS implement short-LED protection?

Short-LED protection triggers when FB voltage exceeds 580mV for ≥1 µs-indicating excessive current through R_FB due to LED string open-circuit failure. Upon detection, GATE and COMP are pulled low and the IC latches off until power is cycled, preventing MOSFET overstress and capacitor overvoltage.

Can the MP4008GS operate in SEPIC topology without modification?

Yes-the MP4008GS supports SEPIC topology natively. Its current-mode architecture, fixed 180kHz frequency, and integrated slope compensation eliminate need for external compensation changes. Refer to Figure 7 in the datasheet for the validated SEPIC schematic with component values and layout guidelines.

What is the maximum allowable duty cycle and how is it enforced?

The MP4008GS limits maximum duty cycle to 96% (typical) via internal timing circuitry. This prevents uncontrolled on-time during light-load or fault conditions, ensuring safe operation and enabling reliable current limiting even at low input voltages or high output ratios.

Does the MP4008GS require an external bootstrap capacitor for the gate driver?

No-the MP4008GS does not use a high-side gate driver and therefore does not require a bootstrap capacitor. The GATE pin directly drives the source of an external N-channel MOSFET in low-side configuration (boost) or floating configuration (SEPIC), simplifying layout and reducing BOM count.

How is thermal performance affected by PCB layout in SOIC-8 package?

Thermal resistance θ_JA drops from 96°C/W (standard 2-layer) to 45°C/W (4-layer with 2-in² copper pour under exposed pad) - so routing 4+ thermal vias from the exposed pad (Pin 2 GND) to inner ground planes is essential to maintain T_J ≤125°C at full load in enclosed enclosures.

What PWM frequency range is supported for dimming without audible noise?

MP4008GS supports PWM dimming frequencies from 100 Hz to 25 kHz. Frequencies >20 kHz avoid audible coil whine and enable flicker-free operation; the internal oscillator synchronizes to the PWM signal edge, ensuring jitter-free dimming even at 1% duty cycle.