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Diodes AH284 User Manual

Ah284, Hall-effect smart fan motor controller, Description

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AH284

HALL-EFFECT SMART FAN MOTOR CONTROLLER

AH284

Document number: DS31051 Rev. 11 - 2

1 of 10

www.diodes.com

June 2010

© Diodes Incorporated

Description

The AH284 is a single-chip solution for driving two-coil

brushless direct current (BLDC) fans and motors. The device

includes a Hall-effect sensor, dynamic offset correction and

two complementary open-drain output drivers with internal

Zener diode protection.

To help protect the motor coils, the AH284 provides Rotor

Lock Protection which shuts down output drives if rotor lock is

detected. The device automatically re-starts when the rotor

lock is removed.

The AH284 is available in SIP4 and SOT89-5L packages.

Features

• Single-chip

solution

• Operating Voltage: 3.8V to 20V

• Built-in Hall sensor and input amplifier

• Rotor Lock Protection (Lock detection, output shutdown

and automatic re-start)

• Built-in Zener protection for output driver

• Average output current up to 500mA

• Packages: SIP-4L and SOT89-5L

• Green Molding Compound

Pin Assignments

284

1 2

4

3

1 : Vdd

2 : DO

3 : DOB

4 : GND

SIP-4L

(Top View)

1

2

3

74

5

DOB

DO

GND

NC

Vdd

SOT89-5L

284

(Top View)

Applications

• Two-coil BLDC cooling fans

• Low to medium voltage, low power BLDC motors

Typical Application Circuit

(Note 1)

V

dd

DOB

GND

12V

D2

L2

L1

284

1

2

3

4

D1

R1

R2

C1

C2

D3

DO

C3

Notes: 1. Typically it is recommended to us a 56 Ohm resistor for R1 and R2 and a 2.2

μF E-Cap capacitor for C1, C2 and C3. These values

may need to be optimized depending on the coils used.

To help with IC protection it’s advised to add a Zener diode between Vdd and ground. The Zener diode should be chosen to help
prevent the supply voltage exceeding the maximum rating of the device.