Monolithic Power Systems Inc. MP8756GD-P

Overview

MP8756GD-P from Monolithic Power Systems is a synchronous step-down DC/DC converter delivering 6A continuous output current with adaptive constant-on-time (COT) control, 700kHz switching frequency, and 0.6V to 5.5V adjustable output voltage across a 4.5V–26V input range. It integrates high- and low-side MOSFETs (R_DS(ON) = 30mΩ / 15mΩ), supports ultrasonic mode (USM) for audible-noise-free light-load operation, and is deployed in laptop CPU core power rails.

For engineers reviewing the MP8756GD-P datasheet, MP8756GD-P pinout, MP8756GD-P application, or MP8756GD-P equivalent, key selection criteria include its 117µA quiescent current in PFM mode, DC auto-tune loop for ±1% load/line regulation, integrated output discharge, and QFN-12 (2mm×3mm) thermal performance (θ_JA = 70°C/W).

Technical Context

The MP8756GD-P employs adaptive COT control with internal ramp compensation and a DC auto-tune loop that dynamically adjusts the reference comparator input to correct steady-state V_FB–V_REF error without degrading transient response. Its valley-current OCP uses the low-side MOSFET's R_DS(ON) as a sensing element, with a fixed 9–12A trip threshold.

Operation spans forced PWM, PFM-with-USM (MODE floating), and PFM-without-USM (MODE grounded); USM maintains switching >20kHz at light loads by shrinking T_ON and discharging V_OUT when FB falls below 102% of V_REF. Thermal shutdown activates at 150°C with 25°C hysteresis, and UVLO has 4.25V rising threshold with 250mV hysteresis.

Key Specifications

Pinout & Package

MP8756GD-P is housed in a thermally enhanced QFN-12 package (2mm × 3mm, 0.5mm pitch) with exposed thermal pad (PGND-connected) for efficient heat dissipation in space-constrained applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down converter applications.

Compared with RT6253BGQW and TPS546B24A, MP8756GD-P delivers superior light-load acoustic performance via USM, lower quiescent current than the Richtek part, and simpler analog implementation versus the TI digital controller - making it optimal for cost-, size-, and noise-sensitive embedded systems.

Availability

MP8756GD-P is available at Aetrix Electronics and suitable for laptop power delivery, tablet PC SoC rails, and distributed telecom power systems requiring stable component supply, consistent parametric performance, and long-term production continuity.

Supply support for MP8756GD-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-performance analog and power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP8756 belongs to MPS' high-current monolithic buck converter product line, engineered for compact, high-efficiency DC/DC conversion in portable computing and infrastructure equipment where thermal density and acoustic noise are critical constraints.

FAQ

What is the minimum recommended output capacitance for stable operation?

The MP8756GD-P is stable with as little as 22µF of ceramic output capacitance when used with the internal ramp compensation and DC auto-tune loop. For POSCAP or electrolytic outputs, 88µF is recommended per the typical application schematic; stability does not require ESR-based damping networks.

How does the MODE pin affect efficiency and noise performance?

When MODE is floating, the device operates in PFM with ultrasonic mode (USM), maintaining >20kHz switching at light loads to eliminate audible coil whine while achieving ~85% efficiency at 10mA. Grounding MODE disables USM, allowing sub-20kHz skipping - quieter under no load but potentially audible at medium loads.

Can MP8756GD-P safely drive a pre-biased output during start-up?

Yes. The MP8756GD-P features pre-bias start-up protection: if the output is already charged when EN rises, the IC inhibits switching until the internal reference voltage exceeds the sensed FB voltage, preventing reverse current flow and output voltage overshoot.

What is the maximum allowable inductor DCR for accurate valley-current OCP?

The OCP circuit relies on low-side MOSFET R_DS(ON) (15mΩ typ) as the current-sense element, not inductor DCR. Therefore, inductor DCR has no impact on OCP accuracy - enabling use of low-DCR shielded power inductors without calibration or compensation.

Does the MP8756GD-P support output voltage tracking during power sequencing?

No. MP8756GD-P lacks dedicated tracking pins or programmable soft-start delay; output voltage ramps monotonically from 0V to target in ~1.2ms. For multi-rail sequencing, external enable timing control (e.g., RC delay on EN) or a dedicated sequencer IC is required.

How is thermal performance validated in the QFN-12 package?

Thermal resistance is measured per JESD51-7 on a 4-layer PCB with 2oz copper, 1in² thermal pad copper pour, and 6 thermal vias under the exposed pad. θ_JA = 70°C/W and θ_JC = 15°C/W are guaranteed test conditions - actual board layout must replicate this copper area and via count to achieve rated 6A performance.

What happens during an over-voltage fault condition?

When V_FB exceeds 122% of V_REF, the high-side switch turns off and the low-side switch turns on continuously, discharging the output through the LS-FET body diode and R_DS(ON). The device exits OVP regulation once V_FB falls below 117% V_REF, restoring normal COT operation.