Datasheet

MAX6643/MAX6644/MAX6645
Automatic PWM Fan-Speed Controllers with
Overtemperature Output
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MAX6643
MAX6644
MAX6645
DXP1/(DXP)
DXP2
TEMPERATURE
SENSOR
TEMPERATURE
LOGIC
PWM
GENERATOR
FAN-FAIL
DETECTION
DUTY CYCLE
ANALOG SENSE
TACHOMETER
LOCKED ROTOR IN
ANALOG SENSE
TACHOMETER
LOCKED ROTOR IN
OT TH TL
THRESHOLD
SELECTION
FULLSPD/(FULLSPD)
PWM_OUT
FAN_IN1
FAN_IN2
FANFAILTACHSET
OT1 OT2 TH1 TH2 TL1 TL2
() ARE FOR MAX6643 ONLY.
Block Diagram
TO FANFAIL
ALARM
MAX6643
TH1
16
15
14
13
12
11
(TACHOMETER MODE)
(TACHOMETER MODE)
TO OVERTEMPERATURE ALARM
10
9
TL2
TL1
FANFAIL
TACHSET
FULLSPD
GND
DXP
V
DD
V
DD
(+3.0V TO +5.5V)
+V
FAN
(5V OR 12V)
1
2
3
4
5
6
7
8
TH2
OT1
OT2
PWM_OUT
FAN_IN1
FAN_IN2
OT
4.7kΩ
4.7kΩ
4.7kΩ
N
Typical Operating Circuit