Monolithic Power Systems Inc. MP8638GQ-P

Overview

MP8638GQ-P from Monolithic Power Systems is a fully integrated, synchronous step-down DC/DC converter delivering up to 12A continuous output current with adjustable current limit (7–16A), adaptive constant-on-time control, and internal 11mΩ/6mΩ MOSFETs. It operates from 4.5V–16V input, supports 0.6V–5.5V output, and targets high-density POL applications in servers and networking equipment.

For engineers reviewing the MP8638GQ-P datasheet, MP8638GQ-P pinout, MP8638GQ-P application, or MP8638GQ-P equivalent, key selection criteria include its QFN-16 (3mm×3mm) package, CLM-based current limit configuration, MODE1/MODE2 dual-mode selection for fSW and VCC sourcing, and PG open-drain power-good signaling with 95%/90% VREF thresholds.

Technical Context

The MP8638GQ-P implements adaptive constant-on-time (COT) control with DC auto-tune loop and remote differential sense, enabling fast transient response without external compensation while maintaining stability with ceramic or POSCAP output capacitors. Its valley-current sensing OCP uses the LS-FET's R_DS(ON) as the current-sense element, eliminating need for external sense resistors.

It integrates dual-mode VCC supply selection (internal 3.3V regulator or external 3.3V via MODE2), programmable switching frequency (700 kHz or 1000 kHz via MODE1 resistor), and configurable current limit (7A/10A/13A/16A via CLM-to-PGND resistor). The device transitions seamlessly between CCM and DCM, using skip-mode at light loads to maintain >90% efficiency down to 10mA.

Key Specifications

Pinout & Package

MP8638GQ-P is housed in a thermally enhanced QFN-16 (3mm × 3mm, 0.5mm pitch) package with exposed thermal pad. Pin 1 is marked by dot; top-side marking includes "BZG" product code, year code, and lot number.

Key Features

Applications

Equivalent & Alternatives

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

Compared with RTQ2132BGQW and TPS546D24RSAR, MP8638GQ-P offers superior design simplicity for 12A POL use cases-requiring zero external compensation, supporting analog current limit tuning, and delivering tighter reference accuracy (±1%) in a smaller QFN-16 package.

Availability

MP8638GQ-P is available at Aetrix Electronics and suitable for server power delivery, telecom base station POL, and high-end graphics card voltage regulation requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for MP8638GQ-P 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-efficiency, high-reliability power management ICs for computing, automotive, and industrial markets.

The MP8638 belongs to MPS's high-current monolithic buck converter product line, engineered specifically for dense, thermally constrained POL applications where minimal external components and predictable current-limit behavior are critical.

FAQ

What is the minimum recommended input capacitance for MP8638GQ-P at 12V input and 12A load?

A minimum 100µF low-ESR input capacitor is required-typically implemented as one 100µF POSCAP (25mΩ) paralleled with three 22µF X7R ceramics. This combination suppresses high-frequency switching noise and limits VIN ripple to <200mV_pp under 12A load steps, preventing UVLO triggering.

How does the CLM pin configure the current limit, and what resistor values yield 10A and 13A settings?

The CLM pin sets ILIMIT by connecting a resistor between CLM and PGND. Per Table 3 in the datasheet, 90kΩ yields 10A and 150kΩ yields 13A-both using 1% tolerance metal-film resistors. No calibration or trimming is needed; the device reads the resistor value directly to configure internal current-sense gain.

Can MP8638GQ-P operate with only ceramic output capacitors, and what is the minimum recommended value?

Yes-it is fully stable with ceramic-only output capacitors due to internal ramp compensation. Minimum recommended value is 100µF total (e.g., one 100µF X7R or four 22µF 0805 ceramics), placed within 3mm of the FB and SW pins. This achieves <30mV_pp ripple at 12A/5V without requiring POSCAP or aluminum electrolytics.

What happens during a short-circuit event, and how does recovery occur?

Upon short-circuit, valley-current OCP triggers immediately, disabling PWM. The LS-FET remains on until inductor current reaches zero, then the device enters hiccup mode-restarting every ~20ms. Recovery is automatic once the fault clears; no manual reset is needed unless latched by UVP2 (VFB <50% VREF), which requires EN toggle or VIN cycle.

Is the PG signal compatible with 1.8V logic, and what pull-up voltage is recommended?

PG is an open-drain output rated for 4mA sink at 0.4V. It is compatible with 1.8V, 3.3V, or 5V logic-simply pull up to the target logic rail (e.g., 3.3V) via a 100kΩ resistor. The 95%/90% VREF thresholds ensure clean assertion/deassertion even with 100mV of noise on the feedback divider.

Does MP8638GQ-P support pre-biased output startup, and how is it managed?

Yes-when EN is asserted and FB senses a pre-charged output voltage above the target VREF, both HS- and LS-FETs remain off until the internal soft-start ramp exceeds the sensed FB voltage. This prevents reverse current flow and ensures monotonic startup without output voltage overshoot or oscillation.

What thermal derating applies above 70°C ambient, and how is θJA measured?

With θJA = 55°C/W on a 4-layer JEDEC JESD51-7 PCB, maximum continuous power dissipation drops linearly: at 70°C ambient, PD_MAX = (150°C − 70°C)/55°C/W = 1.45W. Derating begins immediately above 25°C; full 12A output requires adequate copper pour and thermal vias under the exposed pad to sustain TJ <125°C.