AH280A-PA-A View Datasheet(PDF) - Anachip Corporation

Part Name

Description

View to exact match

AH280A-PA-A

Hall-Effect Smart Fan Driver

Anachip Corporation 

Hall-Effect Smart Fan Driver

AH280

„ Rotation detection

The automatic restart circuit detects a motor lock

condition and automatically turns off the output

current. When the lock condition is cleared, the IC

automatically restarts and allows the motor to run.

In the AH280, automatic restart is performed in the

following manner. A motor lock condition is

detected when the Hall signal stops switching.

The output is ON when CT pin is being charged,

and OFF when CT pin is being discharged.

Hall input

Motor output

CT

ON

OFF

CT

clamp

voltage

Motor locked

Motor locked detected

CT

comparator

voltage

Ton*

Toff*

Motor locked

cleared

Reverts to normal operation

Output ON time (Ton) and OFF time (Toff)

Determined by the CT pin capacitor

Where

Ton=

C

×

(VCL

−

V

CP

)

(sec)

I

CHG

Toff= C × (VCL − VCP ) (sec)

IDHG

C is the capacitance of the CT pin external capacitor

VCL is the CT pin clamp voltage

VCP is the CT pin comparator voltage

ICHG is the CT pin charge current

IDHG is the CT pin discharge current

Anachip Corp.

www.anachip.com.tw

Rev. 0.7 Apr 16, 2004

4/7

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