Environmental Monitoring and Control Device
Datasheet
Example for PWM1 assigned to Zone 1:
Zone 1 Fan Temp Limit (Register 67h) is set to 50°C (32h).
Range (Register 5Fh) is set to 8°C (7h)
Fan1 PWM Minimum (Register 64h) is set to 50% (80h)
In this case, the PWM1 duty cycle will be 50% at 50°C.
Since (Zone 1 Fan Temp Limit) + (Fan 1 Range) = 50°C + 8°C = 58°C, the fan will run at 100% duty
cycle when the temperature of the Zone 1 sensor is at at 58°C.
Since the midpoint of the fan control range is 54°C, and the median duty cycle is 75% (Halfway between
the PWM Minimum and 100%), PWM1 duty cycle would be 75% at 54°C.
Above (Zone 1 Fan Temp Limit) + (Fan 1 Range), the duty cycle must be 100%.
The PWM frequency bits [2:0] determine the PWM frequency for the fan.
Table 8.8 - Register Setting vs. PWM Frequency
PWM Frequency Selection (Default =011=29.3Hz)
FREQ[2:0]
000
PWM FREQUENCY
11.0 Hz
14.6 Hz
001
010
011
100
101
110
111
21.9 Hz
29.3 Hz
35.2 Hz
44.0 Hz
58.6 Hz
87.7 Hz
Table 8.9 - Register Setting vs. Temperature Range
Range Selection (Default =1100=32°C)
RAN[3:0]
0000
RANGE (°C)
2
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
2.5
3.33
4
5
6.67
8
10
13.33
16
20
26.67
32
40
53.33
80
SMSC EMC6D100/EMC6D101
Page 54
Rev. 09-09-04
DATASHEET
SMSC [ SMSC CORPORATION ]
