Allegro MicroSystems A4930METTR-T

Overview

A4930METTR-T from Allegro MicroSystems is a single-phase brushless DC fan pre-driver IC designed to control four external N-channel MOSFETs in full-bridge topology. It integrates synchronous rectification, internal 5 V and 8 V regulators, Hall sensor interface, PWM current limiting, and lock-detect protection. Operates from 8–36 V supply, supports 15–27 kHz internal PWM frequency, and delivers gate drive outputs up to 8.5 V with 700–1300 ns dead time - enabling high-efficiency thermal management in server cooling and industrial blowers.

For engineers reviewing the A4930METTR-T datasheet, A4930METTR-T pinout, A4930METTR-T application, or A4930METTR-T equivalent, this page provides verified functional context, validated pin roles, confirmed thermal and electrical specifications, and real-world selection guidance for fan motor control systems requiring robust rotor lock detection and low-power dissipation.

Technical Context

The A4930METTR-T implements Hall-based commutation logic with 10 mV typical differential threshold and 5–35 mV hysteresis, enabling precise zero-crossing detection for single-phase BLDC fans. Its internal charge pump generates VCP above VBB to drive high-side N-MOSFETs, while synchronous rectification circuitry actively turns on appropriate low-side FETs during current decay to bypass body diode conduction.

Protection architecture includes thermal shutdown at 165°C (15°C hysteresis), VBB undervoltage lockout at 7.5–7.85 V, VCP UVLO at 5.4 V, and lock-detect timing set by CLD capacitor (tLD = CLD × 10 s/µF). Soft start ramp rate is programmable via SS pin capacitor, and current limit is set by external RSENSE using VREF/5 scaling.

Key Specifications

Pinout & Package

Package: 28-pin QFN (5 mm × 5 mm, 0.90 mm nominal height) with exposed thermal pad (suffix ET); RoHS-compliant, 100% matte tin leadframe plating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-phase BLDC fan pre-driver applications.

Compared with A4930GETTR-T, the A4930METTR-T lacks AEC-Q100 qualification but shares identical thermal, electrical, and functional behavior - making it ideal for cost-sensitive industrial designs. Against MP6532DJ-LF-Z, A4930METTR-T offers superior voltage margin, Hall-based accuracy, and external MOSFET flexibility at the expense of component count.

Availability

A4930METTR-T is available at Aetrix Electronics and suitable for data center server cooling, industrial blower control, and telecom base station thermal management requiring stable component supply and long-term production continuity.

Supply support for A4930METTR-T 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

Allegro MicroSystems is a U.S.-based designer of high-performance magnetic sensing and power ICs, specializing in motion control, current sensing, and motor driver solutions since 1989.

The A4930 product line targets single-phase brushless fan control in high-reliability thermal systems, emphasizing integrated protection, Hall interface fidelity, and MOSFET drive efficiency for server, industrial, and medical applications.

FAQ

What is the function of the CLD pin on the A4930METTR-T?

The CLD pin on the A4930METTR-T connects to an external capacitor that sets the locked-rotor detection timeout. The device measures time between FG pulses; if none occur within tLD = CLD × 10 s/µF, it asserts RD high and disables source drivers. For example, a 0.1 µF capacitor yields ~1 s tLD, enabling rapid stall response in safety-critical fans. This timing is independent of ambient temperature and internally calibrated.

Does the A4930METTR-T require external MOSFETs, and what type are supported?

Yes, the A4930METTR-T is a pre-driver and requires four external N-channel MOSFETs arranged in a full-bridge configuration. It drives both high-side (via charge pump) and low-side FETs with 7–8.5 V gate swing and 20 mA peak drive current. The IC's synchronous rectification logic actively controls which low-side FET conducts during current decay, eliminating reliance on body diodes and reducing power loss in the external FETs.

How does the A4930METTR-T implement current limiting during fan startup?

The A4930METTR-T uses a current-sense amplifier referenced to VREF/5 to monitor voltage across an external RSENSE resistor. When sensed current reaches ITRIP = VREF / (5 × RSENSE), the internal PWM comparator resets the source-enable latch, turning off high-side drivers. This cycle repeats at the internal PWM frequency (15–27 kHz), regulating peak winding current. A soft-start capacitor on SS pin further ramps the effective duty cycle to limit inrush.

Can the A4930METTR-T operate without a Hall sensor?

No - the A4930METTR-T requires differential Hall inputs (HP/HN) for commutation timing and cannot operate in sensorless mode. Its block diagram and functional description confirm Hall-based zero-crossing detection is fundamental to its operation. Attempting to run without Hall signals results in undefined state transitions, failed startup, and potential RD fault assertion. For sensorless alternatives, consider Allegro's A4964 or other dedicated sensorless pre-drivers.

What is the purpose of the CP1 and CP2 pins on the A4930METTR-T?

The CP1 and CP2 pins on the A4930METTR-T form the external charge pump network that generates VCP - a voltage above VBB used to drive the high-side N-channel MOSFET gates. CP1 connects to the charge pump flying capacitor, while CP2 connects to the reservoir capacitor (VCP). This two-capacitor topology ensures stable high-side gate drive even during PWM transitions, enabling efficient full-N-MOSFET bridge operation without P-channel devices or external bootstrap circuits.