w83627ef Winbond Electronics Corp America, w83627ef Datasheet - Page 35

• Manufacturer Part Number: w83627ef
• Description: Lpc Super I/o For Desktop & Server
• Manufacturer: Winbond Electronics Corp America

The default divisor is 2 and defined at Bank0 Index 47h.bit7~4, Index 4Bh.bit7~6, Index 4Ch.bit7,
Index 59h.bit7.bit3~2 and Index 5Dh.bit5~7 which are three bits for divisor. That provides very low
speed fan counter such as power supply fan. The followed table is an example for the relation of
divisor, RPM, and count.
6.4.2
W83627EHF/EHG provides two controllable methods for Fan speed control. One is PWM duty cycle
output and the other is DC voltage output. Either PWM or DC output can be programmed at Bank0
Index 04h.bit1~0 , Index 12h.bit0 and Index 62h.bit6.
6.4.2.1. PWM Duty Cycle Output
The W83627EHF/EHG provides maximum 4 sets for fan PWM speed control. The duty cycle of PWM
can be programmed by a 8-bit registers which are defined in the Bank0 Index 01h, Index 03h, Index
11h and Index 61h. The default duty cycle is set to 100%, that is, the default 8-bit registers is set to
FFh. The expression of duty can be represented as follows.
The PWM clock frequency also can be program and defined in the Bank0 Index 00h, Index 02h, Index
10h and Index 60h.
6.4.2.2. DC Voltage Output
The W83627EHF/EHG has a 6 bit DAC which produces 0 to 3.3 volts DC output that provides
maximum 4 sets for fan speed control. The analog output can be programmed in the Bank0 Index 01h,
Index 03h, Index 11h and Index 61h. The default value is 111111YY,YY is reserved 2 bits, that is
default output value is nearly 3.3 V. The expression of output voltage can be represented as follow ,
2 (default)
DIVISOR
128
16
32
64
1
4
8
Fan speed control
Output Voltage (V)
NOMINAL RPM
Dutycycle
8800
4400
2200
1100
550
275
137
68
(%)
= VCC
=
REVOLUTION
3
109.08 ms
218.16 ms
436.32 ms
872.64 ms
Programmed
TIME PER
13.64 ms
27.27 ms
54.54 ms
6.82 ms
W83627EHF/EF, W83627EHG/EG
×
Programmed
Table 6.2
- 29 -
- 8
255
bit
COUNTS
153
153
153
153
153
153
153
153
Register
- 6
64
bit
Register
Value
Publication Release Date: Nov. 2006
70% RPM
6160
3080
1540
770
385
192
96
48
×
Value
100
%
`
TIME FOR 70%
1246.72 ms
155.84 ms
311.68 ms
623.36 ms
19.48 ms
38.96 ms
77.92 ms
9.84 ms
Revision 1.3