w83627thg Winbond Electronics Corp America, w83627thg Datasheet - Page 35

• Manufacturer Part Number: w83627thg
• Description: Winbond Lpc I/o
• Manufacturer: Winbond Electronics Corp America

5.4.2
The W83627THF 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 Index 01h, Index 03h
and Index 11h. The default value is 0xFY,Y is reserved nibble, that is default output value is 5 V. The
expression of output voltage can be represented as follow ,
OUTPUT Voltage
The application circuit is shown as follow,
Must be take care when choosing the OP-AMP and the transistor. The OP-AMP is used for amplify the
5V range of the DC output up to 12V . The transistor should has a suitable β value to avoid its base
current pulling down the OP-AMP ’s output and gain the common current to operate the fan at fully
speed.
5.5
SmartFan
Speed Cruise mode. No matter which mode you use, the FAN will full speed run at beginning.
FANOUT
SmartFan
Fan speed control
TM
Control provides two mechanisms. One is Thermal Cruise mode and the other is Fan
R1
TM
0
= AVCC
Control
C1
0.1U
×
Programmed
R4
20K
3
2
IO-12V
IO+12V
4
11
+
-
Figure 5-8
LM358
- 28 -
28K
- 4
1
R3
16
bit
W83627THF/W83627THG
Register
IO+12V
NPN
Q1
Value
FAN
3
2
1
Tachometer output