W83627EHF_0611 Datasheet, PDF (35/144 Pages) Winbond – WINBOND LPC I/O

W83627EHF/EF, W83627EHG/EG
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.
DIVISOR
1
2 (default)
4
8
16
32
64
128
NOMINAL RPM
8800
4400
2200
1100
550
275
137
68
TIME PER
REVOLUTION
COUNTS
6.82 ms
153
13.64 ms
153
27.27 ms
153
54.54 ms
153
109.08 ms
153
218.16 ms
153
436.32 ms
153
872.64 ms
153
Table 6.2
70% RPM
6160
3080
1540
770
385
192
96
48
TIME FOR 70%
9.84 ms
19.48 ms
38.96 ms
77.92 ms
155.84 ms
311.68 ms
623.36 ms
1246.72 ms
6.4.2 Fan speed control
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.
Dutycycle(%) = ^{Programmed 8 - bit Register Value} ×100%
255
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 ,
Output Voltage (V) = 3VCC × ^{Programmed 6 - bit Register Value} `
64
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Publication Release Date: Nov. 2006
Revision 1.3