Rainbow Electronics MAX6645 - Manual (Page 9)

MAX6643/MAX6644/MAX6645
Automatic PWM Fan-Speed Controllers with
Overtemperature Output
_______________________________________________________________________________________ 9
MAX6644
1
2
3
4
TH1
TL2
TL1
FANFAIL
TACHSET
DXP2
GND
DXP1
V DD
TH2
OT1
OT2
PWM_OUT
FAN_IN1
FAN_IN2
OT
5
6
7
8
16
15
4.7k Ω 4.7k Ω
+V FAN (5V OR 12V) V DD (+3.0V TO +5.5V) +V FAN (5V OR 12V)
2.0 Ω 2.0 Ω
4.7k Ω
TO FANFAIL
ALARM
0.1 µF
0.1 µF
14
13
CURRENT-SENSE
MODE
CURRENT-SENSE
MODE
TO OVERTEMPERATURE
ALARM
12
11
10
9
N
N
MAX6645
1
FANFAIL
TACHSET
DXP2
GND
DXP1
V DD
PWM_OUT
FAN_IN1
FAN_IN2
OT
2
3
4
5
4.7k Ω 4.7k Ω
+V FAN (5V OR 12V) V DD (+3.0V TO +5.5V) +V FAN (5V OR 12V)
4.7k Ω
TO FANFAIL
ALARM
10
TACHOMETER MODE
TACHOMETER MODE
TO OVERTEMPERATURE
ALARM
9
8
7
6
N
Figure 3. MAX6644 Using Two External Transistors to Measure Remote Temperatures and Control Two 2-Wire Fans. The fan’s power-
supply current is monitored to detect failure of either fan. Connect pin 10 to pin 11 if only one fan is used.
Figure 4. MAX6645 Using Two External Transistors to Measure Remote Temperatures and Control Two 2-Wire Cooling Fans. The
fan’s power-supply current is monitored to detect failure of either fan. Connect FAN_IN1 to FAN_IN2 if only one fan is used.