W83792AD/AG/D/G
7.7.2.1. PWM mode :
Programmed8 - bit Register Value
Duty − cycle(%) =
×100%
255
+12V
R1
R2
PNP Transistor
D
G
PWM Clock Input
NMOS
S
+
-
C
FAN
Figure 6.
7.7.2.2. DC mode:
W83792D/G has a 4-bit DAC, which produces 0 to 5 volts DC output that provides maximum 3 sets for
fan speed control. The analog output can be programmed in the Bank0 CR[81], CR[83], CR[94],
CR[A3],CR[A4] and CR[A5]. That is default output value is 5 V. The expression of output voltage can
be represented as follow,
Programmed 4 - bit Register Value
OUTPUT VOLTAGE = AVCC ×
16
The application circuit is shown as follow,
IO+12V
IO+12V
Q1
NPN
R1
0
LM358
1
4
+
3
2
FANOUT
-
C1
Tachometer output
0.1U
3
2
1
11
R3
IO-12V
FAN
47K
R4
33K
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