Diodes Incorporated AH5795-FDC-7

Overview

AH5795-FDC-7 from Diodes Incorporated is a single-phase Hall-effect latch fan motor driver IC integrating a Hall sensor, amplifier, and full-bridge output stage in a DFN2020C-6 package. It drives single-coil BLDC fans with 1.8–6 V supply, supports dual speed control (PWM input or Vdd modulation), delivers up to 1000 mA peak output current, and features rotor lock protection with auto-restart and open-drain FG tachometer output for speed monitoring in low-noise cooling applications.

For engineers reviewing the AH5795-FDC-7 datasheet, AH5795-FDC-7 pinout, AH5795-FDC-7 application, or AH5795-FDC-7 equivalent, key selection considerations include its soft-switching commutation for EMI reduction, dual-speed-control flexibility, thermal shutdown at 175°C, FG output timing alignment with magnetic transitions, and compatibility with space-constrained 3.3 V/5 V fan designs requiring integrated Hall sensing.

Technical Context

The AH5795 implements a closed-loop commutation system using an on-chip Hall sensor to detect rotor position and drive complementary O1/O2 outputs via a soft-switching full-bridge. Its logic block includes lock detection that disables outputs after 65 ms of PWM low and initiates automatic restart upon recovery.

Functional operation relies on magnetic hysteresis (Bop = 10–50 G, Brp = −50 to −10 G) and generates FG pulses synchronized to magnetic edge transitions-not motor rotation frequency directly. The FG output is open-drain with ≤0.4 V low-level voltage at 5 mA sink current and ≤5 µA leakage.

Key Specifications

Pinout & Package

AH5795-FDC-7 is housed in a 2.0 mm × 2.0 mm × 0.6 mm DFN2020C-6 package with exposed thermal pad, optimized for compact fan modules and thermally constrained PCB layouts.

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 A3920KLPTR-T, AH5795-FDC-7 uniquely integrates Hall sensing, FG tachometer, and autonomous rotor lock recovery in a 2 mm × 2 mm package-reducing component count, PCB area, and firmware overhead for compact, low-noise fan control.

Availability

AH5795-FDC-7 is available at Aetrix Electronics and suitable for 3.3 V notebook cooling fans, 5 V instrumentation fan modules, and low-power industrial sensor enclosure fans requiring stable component supply, consistent thermal performance, and RoHS-compliant packaging.

Supply support for AH5795-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 discrete semiconductors and ICs, specializing in power management, signal integrity, and precision analog solutions for high-volume industrial and consumer applications.

AH5795 belongs to Diodes' fan motor driver product line, designed specifically for space-constrained, low-noise BLDC cooling systems requiring integrated Hall sensing, soft switching, and autonomous fault recovery.

FAQ

What is the function of the FG pin, and how should it be interfaced?

The FG pin is an open-drain frequency generator output that pulses at each magnetic polarity transition detected by the internal Hall sensor-not per motor revolution. It requires an external 10 kΩ pull-up resistor to Vdd. The output sinks up to 5 mA with ≤0.4 V low-level voltage, making it compatible with standard 3.3 V or 5 V microcontroller GPIO inputs for tachometer counting or stall detection.

How does rotor lock protection operate, and what happens after detection?

Rotor lock is detected when the PWM input remains low for longer than 65 ms, triggering immediate shutdown of O1 and O2 outputs. Once the PWM signal returns high, the device automatically re-starts commutation without host intervention. This behavior is implemented entirely in hardware and does not require firmware polling or reset sequences.

Can AH5795-FDC-7 drive a 12 V fan?

No. AH5795-FDC-7 has a maximum supply voltage of 7 V absolute rating and recommended operating range of 1.8–6 V. Attempting to operate it at 12 V will cause permanent damage. For 12 V fans, consider Diodes' AH9485 (2.7–18 V range), which uses an external Hall sensor but lacks integrated FG output and auto-restart.

What is the significance of soft switching in this driver?

Soft switching controls the slew rate of O1/O2 voltage transitions to limit dv/dt and di/dt during coil current reversal. This reduces electromagnetic interference (EMI) emissions by over 10 dB and eliminates audible switching noise-critical for fan applications in audio-sensitive or EMC-regulated environments like medical devices and notebooks.