Diodes Incorporated AH5794-FDC-7

Overview

AH5794-FDC-7 from Diodes Incorporated is a single-phase Hall-effect latch fan motor driver IC designed for single-coil BLDC cooling fans. It integrates a Hall sensor, amplifier, full-bridge driver with soft switching, rotor lock protection, thermal shutdown, and open-drain FG tachometer output. Operates from 1.8V to 6V supply, delivers up to 1000mA peak output current, and supports speed control via VDD modulation in netbook, instrumentation, and low-voltage fan applications.

For engineers reviewing the AH5794-FDC-7 datasheet, AH5794-FDC-7 pinout, AH5794-FDC-7 application, or AH5794-FDC-7 equivalent, key selection criteria include its integrated Hall sensing, dual-package availability (U-DFN2020C-6), rotor lock auto-restart behavior, FG output timing alignment with magnetic transitions, and soft-switching EMI reduction-critical for noise-sensitive portable and instrumentation cooling systems.

Technical Context

The AH5794 implements a closed-loop commutation controller using an on-chip Hall sensor to detect rotor position and drive complementary O1/O2 outputs through a full-bridge stage with controlled slew rate (200μs typical). Its lock detection logic monitors stalled conditions by analyzing FG and output state persistence, triggering shutdown and automatic restart upon recovery.

Thermal protection activates at 175°C junction temperature with 25°C hysteresis; the FG output reflects magnetic change frequency-not motor RPM directly-and requires an external 10kΩ pull-up. No external timing capacitor is needed, simplifying layout while maintaining precise commutation timing across 1.8–6V operation.

Key Specifications

Pinout & Package

Available in U-DFN2020C-6: 2.0mm × 2.0mm, 0.5mm pitch, exposed thermal pad, low-profile (0.43mm max height), RoHS-compliant "Green" package.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AH9485 and AH9486, the AH5794-FDC-7 uniquely combines FG tach output, rotor lock auto-restart, and soft switching in a 2mm × 2mm package-making it optimal for compact, self-monitoring, low-noise fan designs where both speed feedback and stall resilience are required.

Availability

AH5794-FDC-7 is available at Aetrix Electronics and suitable for netbook cooling fans, instrumentation thermal management, and low-voltage industrial ventilation systems requiring stable component supply, consistent parametric performance, and long-term lifecycle support.

Supply support for AH5794-FDC-7 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

Diodes Incorporated is a global manufacturer of high-performance discrete semiconductors and analog ICs, serving automotive, industrial, computing, and consumer markets with a focus on power efficiency and reliability.

The AH5794 belongs to Diodes' fan motor driver product line, engineered specifically for integrated, low-noise BLDC fan control in space- and power-constrained applications-emphasizing Hall sensing accuracy, thermal robustness, and EMI mitigation.

FAQ

What is the function of the NC pin on AH5794-FDC-7?

The NC (No Connection) pin is an unconnected die pad with no internal bond wire or circuit connection. It must remain electrically floating-no trace routing, solder mask opening, or grounding is permitted. This pin serves only as a mechanical alignment marker and has zero electrical function.

How does rotor lock detection work in the AH5794-FDC-7?

Rotor lock detection monitors persistent static states on the FG output and O1/O2 terminals. If FG stops toggling while outputs remain active beyond a timeout, the IC interprets this as mechanical stall, disables both outputs, and initiates automatic restart once FG resumes activity-without requiring external microcontroller intervention.

Can the FG output be used to calculate exact motor RPM?

No-the FG output frequency equals the magnetic pole transition rate, not motor RPM. For a 2-pole magnet, FG frequency = RPM/60; for a 4-pole magnet, FG frequency = 2×RPM/60. Accurate RPM calculation requires knowing the magnet pole count and applying the appropriate scaling factor in the host system.

Is AH5794-FDC-7 qualified for automotive use?

No-AH5794-FDC-7 is not AEC-Q100 qualified. Diodes explicitly states that automotive-grade variants (e.g., AEC-Q100-compliant versions) require separate part numbers and PPAP-capable manufacturing. This device is intended for industrial, computing, and instrumentation applications only.