Monolithic Power Systems Inc. MP6545GF-Z

Overview

MP6545GF-Z from Monolithic Power Systems is a three-phase half-bridge power stage IC designed for brushless DC motor drive applications. It integrates six N-channel MOSFETs (three high-side, three low-side), operates from 4.5V to 45V input, delivers up to 2.5A per phase, features 150mΩ typical R_DS(ON) per FET, and includes OCP, OVP, UVLO, and thermal shutdown with open-drain nFAULT reporting. Used in laser printer paper feed systems requiring compact, thermally robust motor control.

For engineers reviewing the MP6545GF-Z datasheet, MP6545GF-Z pinout, MP6545GF-Z application, or MP6545GF-Z equivalent, this page provides verified technical context, package-specific pin mapping, real-world timing behavior, protection threshold values, and validated alternative options for BLDC power stage selection.

Technical Context

The MP6545GF-Z implements independent three-channel half-bridge gate driving with separate HSx/LSx logic inputs per phase, enabling direct microcontroller PWM control without external level-shifting. Its internal charge pump (VCP) generates >VIN+5V for high-side gate drive, while VREG supplies 5V for low-side logic and drivers.

Protection is fully autonomous: over-current detection triggers within 1µs deglitch window on both sourcing and sinking paths; UVLO activates at 4.5V rising threshold with 300mV hysteresis; OVP trips at 45V–48V; thermal shutdown engages at 165°C with 15°C hysteresis. Fault state is latched until nRESET assertion or power cycle.

Key Specifications

Pinout & Package

TSSOP-28EP package (9.7mm × 4.4mm × 1.2mm max height) with exposed thermal pad; 0.65mm pitch; JEDEC MO-153 compliant; MSL Level 2a.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar three-phase half-bridge power stage applications.

Compared with MP6545GF-Z, MP6550GF-Z offers higher current headroom at the cost of increased thermal demand, while STSPIN32F0A trades external control flexibility for integrated intelligence and smaller footprint-making MP6545GF-Z optimal for high-reliability, externally controlled 2.5A BLDC stages.

Availability

MP6545GF-Z is available at Aetrix Electronics and suitable for laser printer paper feed systems, industrial textile spindle drives, compact BLDC fan modules, and automated office copier drum motors requiring stable component supply, consistent tape-and-reel packaging (2500/reel), and long-term lifecycle assurance.

Supply support for MP6545GF-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, founded in 1997 and headquartered in Kirkland, Washington.

The MP6545 belongs to MPS's Simple Three-Phase Power Stage product line, engineered for compact, thermally efficient BLDC motor drive in space- and reliability-constrained industrial and office equipment.

FAQ

What is the maximum allowable continuous output current per phase for MP6545GF-Z at 60°C ambient?

At TA = 60°C, the maximum continuous output current per phase is approximately 2.1A. This derating is based on the TSSOP-28EP package's θJA = 32°C/W and thermal shutdown threshold of 165°C: PD(MAX) = (165 – 60)/32 ≈ 3.3W; with RDS(ON)_LS ≈ 165mΩ and RDS(ON)_HS ≈ 152mΩ, IOUT is limited by conduction loss (I²×R) plus switching loss. Full 2.5A requires TA ≤ 40°C with optimized PCB copper.

Can MP6545GF-Z be used with 3.3V logic-level microcontrollers without level shifters?

Yes. The HSx/LSx inputs accept VIH ≥ 2.0V and VIL ≤ 0.8V, making them compatible with standard 3.3V CMOS outputs. Each input has an internal 100kΩ pull-down resistor, ensuring defined low state when not driven-no external level shifting is required for GPIO-controlled commutation.

How does automatic synchronous rectification improve efficiency in BLDC applications?

During inductive flyback, the MP6545GF-Z turns on the appropriate FET (LS-FET if VOUTx < GND, HS-FET if VOUTx > VIN) instead of relying on lossy body diodes. With typical body diode VF ≈ 1.1V, synchronous rectification reduces conduction loss by >60% at 2A, lowering junction temperature and improving overall system efficiency by 3–5% in continuous operation.

What external capacitors are mandatory for stable operation of MP6545GF-Z?

Four capacitors are mandatory: two 100nF X7R ceramics on VIN pins (one per pin), one 100nF X7R between CPA and CPB, one 1µF X7R from VCP to VIN, and one 1µF X7R from VREG to GND. All must be placed within 2mm of respective pins; bulk electrolytic (e.g., 100µF) is recommended upstream for transient suppression.

Is nFAULT asserted during startup or only during fault conditions?

nFAULT is asserted only during active fault conditions (OCP, OVP, OTP) and remains latched until nRESET is pulsed low or VIN is cycled. It is not asserted during normal startup, sleep entry/exit, or reset recovery-allowing clean system initialization without false fault interrupts.

Does MP6545GF-Z support 100% duty cycle operation on any output channel?

No. Due to charge pump dependency for high-side drive, MP6545GF-Z cannot sustain 100% duty cycle on HS-FETs. Maximum practical HS duty cycle is ~95% at 24V; beyond that, VCP voltage droops, causing HS-FET turn-off. For 100% duty, use LS-FET only (e.g., low-side switch mode) or external bootstrap circuitry.

What is the recommended PCB layout practice for thermal management of MP6545GF-Z?

Maximize copper area on the exposed thermal pad (Pin 28), connect it directly to inner-layer ground planes using ≥9 thermal vias (0.3mm diameter, 0.65mm pitch), extend copper pours under OUT1–OUT3 and PGND pins, and avoid routing signal traces under the IC. Per Figure 3 in the datasheet, ≥200mm² total copper area is required for 2.5A continuous operation at TA = 60°C.