AH5798

SINGLE PHASE HALL EFFECT LATCH SMART

FAN MOTOR CONTROLLER

AH5798 Rev. 1

1 of 9

OCTOBER 2009

www.diodes.com

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Support single-phase full wave DC fan driver

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Built-in Hall sensor input amplifier

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Lock detection and automatic self-restart

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Soft switching for low noise DC fans

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Without external timing capacitor, Reduces the

numbers of external component required

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Thermal protection

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FG output

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Low profile package: SOT89-5L

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SOT89-5L: Available in “Green” Molding Compound

(No Br, Sb)

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Lead Free Finish/ RoHS Compliant (Note 1)

The AH5798 is a single chip solution for driving single-coil

brush-less DC fans and motors.

The AH5798 employs a

bidirectional full bridge driver output stage for single coil fan

motor applications. The soft switching driver generates the low

noise operating for DC fans. The device includes features such

as Rotor Lock Protection with rotor lock detection and automatic

self-restart to avoid damage to the coil when the rotor is blocked.

The AH5798 also offers an externally controlled Tachometer

(Frequency Generator Pin) open -drain output which makes it

easier to connect with external interface such as hardware

monitoring. The FG is the magnetic change frequency. The

device is packaged in SOT89-5L for SMT applications in DC fans.

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3.3V / 5V Min. BLDC Cooling Fans

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Net-Book/ Note-Book DC fans

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Low Voltage/ Low Power BLDC Motors

V

dd

FG

O1

O2

FG

SYSTEM

POWER

V

SS

SYSTEM

POWER

10Kohm

AH5798

Dz

C1

D1

power supply and Vdd terminal. In such case of using reverse power protection diode D1 because of there is no way to return current to power supply,

please take necessary measures like below.

- Connect Dz (Zener diode) between Vdd and Vss terminal, not to exceed the absolute maximum rating voltage.

- Connect a capacitor C1 between Vdd and Vss terminal, to make the path of return current to power supply.

The AH5798 has an open-drain tachometer FG output that follows the magnetic change frequency. A pull-up resistor (10Kohm, typically for System

Power = 5V) connected to a supply voltage.

Features

General Description

Applications

Typical Application Circuit