Environmental Monitoring and Control Device
Datasheet
Table 8.7 - Fan Spin-Up Register
SPIN UP
SPIN[2:0]
TIME
0 sec
000
001
010
100ms
250ms
(default)
011
100
101
110
111
400ms
700ms
1000ms
2000ms
4000ms
8.19 Registers 5F-61h: Auto Fan Speed Range, PWM Frequency
BIT 7
BIT 0
(LSB)
REGISTER
ADDRESS
READ/
WRITE
REGISTER
NAME
DEFAULT
VALUE
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
(MSB)
Fan 1
RAN3
RAN3
RAN3
RAN2
RAN2
RAN2
RAN1
RAN1
RAN1
RAN0
RAN0
RAN0
RES
RES
RES
FRQ2
FRQ2
FRQ2
FRQ1
FRQ1
FRQ1
FRQ0
FRQ0
FRQ0
5Fh
60h
61h
R/W
R/W
R/W
C3h
C3h
C3h
Range/Frequency
Fan 2
Range/Frequency
Fan 3
Range/Frequency
These registers become read only when the Lock bit is set. Any further attempts to write to these registers
shall have no effect.
In Auto Fan Mode, when the temperature for a zone is above the Temperature Limit (registers 67-69h) and
below the Absolute Temperature Limit (registers 6A-6Ch) the speed of a fan assigned to that zone is
determined as follows:
When the temperature reaches the Fan Temp Limit for a zone, the PWM output assigned to that zone is at
Fan PWM Minimum. Between Fan Temp Limit and (Fan Temp Limit + Range), the PWM duty cycle
increases linearly according to the temperature as shown in the figure below.
PWM Duty is linear over
this range
Below Fan Temp Limit: Fan is off or at Fan PWM
Minimum depending on bit[7:5] of register 62h
and bit 2 of register 7Fh
Temperature
Temperature LIMIT: PWM
output at MIN FAN SPEED
LIMIT+ RANGE: PWM
Output at 100% Duty
FIGURE 8.1 - FAN ACTIVITY ABOVE FAN TEMP LIMIT
SMSC EMC6D100/EMC6D101
Page 53
Rev. 09-09-04
DATASHEET
SMSC [ SMSC CORPORATION ]
