emc2101 Standard Microsystems Corp., emc2101 Datasheet - Page 44

• Manufacturer Part Number: emc2101
• Description: Emc2101 Fan Control With 1?c Accurate Temperature Monitoring
• Manufacturer: Standard Microsystems Corp.

Revision 2.53 (02-19-08)
6.21
PWM_D[7:0]
ADDR.
SETTING
4Fh
FFh
01h
11h
20h
47h
C0
C1
PWM_D
R/W
R/W
Maximum resolution is achieved by setting the PWM Frequency Register to 1Fh. With maximum
resolution, the desired PWM frequency can be achieved by adjusting the PWM Frequency Divide
Register setting (PWM_D[7:0]) as shown in
For example, if the user desires a 30Hz PWM frequency with maximum PWM resolution, then the
PWM_F[4:0] bits should be set at 1Fh (31d) and the the PWM_D bits should be set at C1h (193d).
The Fan Control Look-Up Table Hysteresis Register determines the amount of hysteresis applied to
the temperature inputs of the fan control Fan Control Look-Up Table. See
Fan Control Look-Up Table Hysteresis Register
RESOLUTION
EFFECTIVE
Table 6.26 Examples of Fan PWM Frequency with Maximum Resolution
=
1.61
1.61
1.61
1.61
1.61
1.61
1.61
Up Table Hysteresis
(%)
⎛
⎝
Fan Control Look-
------------------------------- -
2 PWM_F
×
REGISTER
360k
Table 6.27 Look Up Table Hysteresis Register
FAN_SETTING)
⎞
⎠
DUTY CYCLE
EFFECTIVE
×
(AT 50%
---------------- -
FREQ
51.6%
51.6%
51.6%
51.6%
51.6%
51.6%
51.6%
1
B7
-
PWM_F[4:0] = 1Fh
=
DATASHEET
---------------- -
FREQ
5806
B6
-
FAN_SETTING)
DUTY CYCLE
44
EFFECTIVE
Table
(AT 75%
77.4%
77.4%
77.4%
77.4%
77.4%
77.4%
77.4%
SMBus Fan Control with 1°C Accurate Temperature Monitoring
B5
-
6.26.
B4
16
PWM_D is the setting of the PWM
PWM_F is the setting of the PWM
Frequency Divide Register (4Eh)
FAN_SETTING
B3
FREQ is the desired PWM
DUTY CYCLE
TO GET 75%
8
Frequency register (4Dh)
2Eh (74.2%)
2Eh (74.2%)
2Eh (74.2%)
2Eh (74.2%)
2Eh (74.2%)
2Eh (74.2%)
2Eh (74.2%)
B2
4
Frequency
Where:
Section
B1
2
FREQUENCY (HZ)
EFFECTIVE PWM
B0
5.6.4.
1
SMSC EMC2101
5806.5
341.6
181.5
81.8
30.2
30.0
22.7
DEFAULT
(4°C)
Datasheet
04h
[5]