TC646B View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

TC646B

PWM Fan Speed Controllers With Auto-Shutdown, Fan Restart and FanSense™ Technology for Fault Detection

Microchip Technology 

TC646B/TC648B/TC649B

Power-Up

Normal

Operation

Power-on

Reset

FAULT = 1

Clear Missing

Pulse Detector

Yes

VIN < VSHDN?

No

Shutdown

VOUT = 0

No

VIN > VREL?

VIN < VAS?

No

Hot Start

Yes

Yes Auto-

Shutdown

VOUT = 0

VIN>

No

(VAS+ VHAS)

Yes

Fire Start-up

Timer

(1 sec)

Fan Pulse

Detected?

Yes

Normal

Operation

Fire Start-up

No

Timer

(1 sec)

Yes Fan Pulse

Detected?

No

Fan Fault

Fan Fault

FAULT = Low,

VOUT = High

VIN< VSHDN?

No

No 16 Pulses

Detected?

Yes

Yes

Shutdown

VOUT = 0

No VIN > VREL? Yes

VIN < VSHDN?

Yes Shutdown

VOUT = 0

No

No

VIN > VREL?

VIN < VAS?

No

VIN > VOTF?

Yes Auto

Shutdown

VOUT = 0

Yes

Power-Up

VIN > No

(VAS + VHAS)

Yes

Yes

Hot Start

FAULT = 0

No

VOUT

Proportional

to VIN

TC646B Only

Yes Fan Pulse No

Detected?

M.P.D.

No Expired?

Yes

Fire

Diagnostic

Timer

(100 msec)

Yes

Fan Pulse

Detected?

No Fire Start-up

Timer

(1 sec)

Yes Fan Pulse

Detected?

No

Fan Fault

Power-Up

Normal

Operation

FIGURE 4-9:

TC646B/TC649B Behavioral Algorithm.

DS21755B-page 16

 2003 Microchip Technology Inc.

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