Monolithic Power Systems Inc. MP8642DU-LF-Z

Overview

MP8642DU-LF-Z from Monolithic Power Systems is a dual-channel synchronous step-down DC/DC converter with integrated 80mΩ high-side MOSFETs per channel, delivering 3A continuous output current per channel across 4.5V–23V input and 0.8V–20V adjustable output ranges. It operates at fixed 600kHz switching frequency with cycle-by-cycle over-current protection, thermal shutdown, and power-good indicators - deployed in flat-panel TV power rails and broadband communication point-of-load regulation.

For engineers reviewing the MP8642DU-LF-Z datasheet, MP8642DU-LF-Z pinout, MP8642DU-LF-Z application, or MP8642DU-LF-Z equivalent, key selection considerations include dual-channel synchronization capability, bootstrap-driven gate drive architecture, 32-pin QFN thermal performance, and end-of-life migration path to MP2393.

Technical Context

The MP8642DU-LF-Z implements peak-current-mode control with independent error amplifiers and COMP nodes per channel, enabling fast transient response and simplified loop compensation using internal optimized networks. Each channel features dedicated EN/SYNC pins supporting both enable/disable control and external clock synchronization up to 1.4MHz.

It integrates dual 5V internal regulators (VCC1/VCC2) for gate driver bias, with bootstrap circuits (BST1/BST2) driving external low-side MOSFETs via BG1/BG2 outputs. Fault management includes UVLO (4.1V rising threshold), latch-off mode on output undervoltage, and thermal shutdown at 150°C with 140°C hysteresis.

Key Specifications

Pinout & Package

MP8642DU-LF-Z is housed in a thermally enhanced 5mm × 5mm, 32-pin QFN package with exposed thermal pad. The package supports high-power density designs and requires PCB copper area under the pad for effective heat dissipation (θ_JA = 36°C/W on 4-layer board).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP8642DU-LF-Z, MP2393DN-LF-Z reduces integration scope to single-channel operation with full integration, while RTQ2132B-QT trades external MOSFET flexibility for higher integration density and simplified layout - neither offers identical dual-channel autonomy or BST-driven gate drive architecture.

Availability

MP8642DU-LF-Z is available at Aetrix Electronics and suitable for flat panel television power rails, digital set-top box core supplies, and broadband communications line cards requiring stable component supply despite its end-of-life status.

Supply support for MP8642DU-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 power management ICs, with design focus on efficiency, integration, and thermal robustness.

The MP8642 belongs to MPS's high-current synchronous buck converter product line, engineered for distributed power architectures in consumer electronics where dual-rail independence, thermal resilience, and EMI-controlled switching are critical.

FAQ

Is MP8642DU-LF-Z still in active production?

No - MP8642DU-LF-Z is officially marked End-of-Life (EOL) by Monolithic Power Systems, with MP2393 recommended as the designated migration path. Aetrix Electronics maintains limited legacy stock with full traceability and supports last-time-buy programs for ongoing production continuity.

What is the function of the BST1 and BST2 pins?

BST1 and BST2 are bootstrap supply terminals that generate a floating voltage rail above SW1/SW2 to fully enhance the external low-side synchronous MOSFETs. Each requires a 0.1–1µF ceramic capacitor connected between BSTx and SWx, and supports optional external diode (e.g., IN4148) for improved efficiency at high duty cycles.

Can MP8642DU-LF-Z operate with only one channel enabled?

Yes - Channel 1 and Channel 2 operate independently. Leaving EN/SYNC2 unconnected or pulled low disables Channel 2 while Channel 1 remains fully functional with its own FB2, PG2, and power path. Grounding unused FB2 or PG2 is not required but must avoid shorting to VOUT or GND.

What thermal derating applies above +85°C ambient?

With θ_JA = 36°C/W on a 4-layer PCB, maximum allowable power dissipation drops linearly: at +100°C ambient, PD_MAX = (150°C − 100°C)/36°C/W ≈ 1.39W. Layout with thermal pad soldering and ≥2 in² copper pour is essential to sustain 3A/channel above 70°C ambient.

Does MP8642DU-LF-Z support forced PWM or PFM mode selection?

No - MP8642DU-LF-Z operates exclusively in fixed-frequency peak-current-mode control. It does not include pulse-frequency modulation (PFM) or mode-select pins. Light-load efficiency relies on reduced switching losses via internal frequency foldback below 250mV FB voltage, not true discontinuous conduction mode.

How is output voltage adjusted on each channel?

Each channel uses a resistor divider from VOUTx to GNDx, with the midpoint connected to FBx. With internal 0.808V reference, output voltage is calculated as VOUT = 0.808V × (1 + R1/R2). Recommended R1 = 40.2kΩ; R2 values for common outputs (e.g., 3.3V → 13kΩ) are provided in the datasheet Table 1.

What failure modes trigger latch-off versus auto-recovery?

Latch-off occurs only during output undervoltage (FB < 0.56V for >100µs), requiring EN or VIN cycling to reset. Cycle-by-cycle overcurrent and thermal shutdown are auto-recovering: current limiting repeats each cycle; thermal shutdown resumes operation once die cools below 140°C.