SDC281 datasheet(7/10 Pages) SDC

7 / 10 page

Datasheet

December, 2013 Rev. 1.1

7/10

2013 Shaoxing Devechip Microelectronics Co., Ltd.

www.sdc-semi.com

Smart Two-Phase DC Fan Driver

SDC281

Function Description

Lock Detection and Auto-restart

SDC281 detects the rotation of the motor by internal

Hall sensor signal, and adjusts lock detection ON time

(tON) and lock detection OFF time (tOFF) by internal

counter.

VDD

DOB

tOFF

Nomal

Spining

Start-up

Spining

tON

Start-up

Spining

Nomal

Spining

Figure 11. Lock Detection and Auto-restart Waveform

Thermal Protection

SDC281 has a thermal protection. When the internal

junction temperature reaches 165°C, the output devices

will be switched off. When the IC’s junction temperature

cools by 30°C, the thermal sensor will turn the output

devices on again, resulting in a pulse output during

continuous thermal protection.

Output Switch Principle

SDC281 built in a Hall-effect sensor plane to sense the

vertical magnetic flux density (B).There are two output

drivers in SDC281 to drive two-phase DC brushless motor.

When the south pole magnetic field is close to the IC

marking surface and the magnetic flux density higher

than operating point(BOP), the DO pin output will turn

ON and the DOB pin output will turn OFF. When the

south pole magnetic field is far away the IC marking

surface and the north pole magnetic field close to the

magnetic flux density until the magnetic flux density

higher than releasing point(BRP), the DOB pin output will

turn ON and the DO pin output will turn OFF.

BOP

BRP

Making Surface

Marking Surface

BOP

BRP

VDO

BOP

BRP

VDOB

BOP

BRP

VDO

BOP

BRP

VDOB

Figure 12. Output Switch Principle

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