Monolithic Power Systems Inc. MP9928GF-Z

Overview

MP9928GF-Z from Monolithic Power Systems is a high-voltage synchronous step-down controller IC designed for industrial and PoE power systems. It operates from 4V to 60V input, drives dual N-channel MOSFETs, supports programmable 100–1000kHz switching frequency, features cycle-by-cycle current limiting with 75mV nominal sense threshold (ILIM = float), and delivers up to 99.5% maximum duty cycle for low-dropout operation in automotive cold-crank scenarios.

For engineers reviewing the MP9928GF-Z datasheet, MP9928GF-Z pinout, MP9928GF-Z application, or MP9928GF-Z equivalent, key selection considerations include its dual-gate driver architecture, AAM/CCM mode selection via CCM/AAM pin, external soft-start capacitor control, precision 0.800V ±12mV feedback reference, and integrated OVP/OCP/thermal shutdown protections.

Technical Context

The MP9928GF-Z implements current-mode PWM control with slope compensation and cycle-by-cycle peak current limiting. Its error amplifier compares FB voltage against a trimmed 0.800V internal reference and generates COMP voltage to modulate top-gate on-time. The controller supports both forced CCM and AAM (Advanced Asynchronous Mode) for light-load efficiency optimization, with AAM entry triggered when COMP falls below VAAM + ~720mV.

It integrates dual gate drivers (TG and BG) with 2Ω pull-up/1Ω pull-down strength, bootstrap supply management via BST/SW, and flexible biasing options: VCC1 can be sourced either from VIN (via internal LDO) or externally from VCC2 (5–12V), reducing dissipation and improving system efficiency. Synchronization capability allows external clock injection at EN/SYNC pin across 100–1000kHz range.

Key Specifications

Pinout & Package

MP9928GF-Z is packaged in TSSOP-20 EP (exposed pad), optimized for thermal performance in high-power DC/DC controllers. Pin functions are validated per Monolithic Power Systems Rev. 1.1 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM5116PW and TPS40210DGQ, MP9928GF-Z offers superior light-load efficiency via AAM, integrated VCC2 biasing for thermal optimization, and complete protection suite (OVP/OCP/thermal/PG) in a single TSSOP-20 EP package-reducing BOM count and layout complexity for mid-power industrial and PoE applications.

Availability

MP9928GF-Z is available at Aetrix Electronics and suitable for PoE-powered devices, USB charging adapters, industrial PLC power modules, and battery-fed linear charger pre-regulators requiring stable component supply across extended temperature and voltage ranges.

Supply support for MP9928GF-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 MP9928 belongs to MPS's high-voltage DC/DC controller product line, engineered for robust, efficient, and compact power conversion in industrial, automotive, and communications infrastructure applications where wide input range and integrated protection are critical.

FAQ

What is the minimum input voltage required for reliable startup of MP9928GF-Z?

The MP9928GF-Z has an input UVLO rising threshold of 4.5V to 5.0V (typical 5.0V). Startup requires VIN ≥ 5.0V; once running, it sustains regulation down to 4.0V due to hysteresis. This enables operation during automotive cold-crank events where battery voltage dips transiently to ~4.5V.

How does the ILIM pin setting affect current limit accuracy and design flexibility?

The ILIM pin selects one of three fixed current-sense thresholds: 25mV (ILIM = GND), 50mV (ILIM = VCC1), or 75mV (ILIM = float). Each setting directly defines the peak inductor current trip point. Choosing 75mV allows higher R_DS(on) MOSFETs or smaller sense resistors, reducing conduction loss while maintaining accurate overcurrent detection.

Can MP9928GF-Z operate without an external VCC2 supply?

Yes. When VCC2 is left open or biased below 4.45V, the MP9928GF-Z automatically sources VCC1 from VIN via its internal 5V LDO. However, using VCC2 (5–12V) reduces power dissipation in the controller, improves overall system efficiency, and lowers thermal stress-especially beneficial in high-input-voltage or high-output-current designs.

What is the functional difference between AAM and CCM modes, and how is mode selection implemented?

AAM (Advanced Asynchronous Mode) disables bottom-FET conduction at light loads to eliminate reverse recovery losses, improving efficiency below ~10% load. CCM (Continuous Conduction Mode) maintains fixed-frequency PWM for predictable EMI and faster transient response. Mode is selected by pulling CCM/AAM pin low (≥480mV threshold) for AAM, or leaving it floating/tied to VCC1 for CCM.

Is the MP9928GF-Z RoHS-compliant and lead-free?

Yes. All MP9928 variants, including MP9928GF-Z, are lead-free, halogen-free, and fully compliant with the EU RoHS directive. MPS confirms green status on its official quality assurance portal, and the TSSOP-20 EP package uses matte tin lead finish compatible with standard Pb-free reflow profiles.

How is the power-good (PG) signal used in system-level power sequencing?

The open-drain PG pin asserts low when VOUT deviates more than ±10% from the regulated setpoint (e.g., 5.0V ±0.5V). It requires an external pull-up resistor (typically 100kΩ to 3.3V or 5V) and provides a 25µs delay for glitch immunity. PG is commonly used to hold microcontroller reset, enable downstream regulators, or trigger system fault logging.

What thermal considerations apply to the TSSOP-20 EP package in high-current designs?

The TSSOP-20 EP package has θ_JA = 40°C/W (4-layer PCB). At 125°C max junction and 85°C ambient, max continuous power dissipation is ~1.0W. For high-current applications, use the exposed pad tied to a large copper pour with multiple thermal vias to internal ground planes to maintain safe operating temperature and avoid thermal shutdown.