SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 260

• Manufacturer Part Number: SCH3112I-NE
• Description: LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
• Manufacturer: SMSC [SMSC Corporation]

Rev 0.2 (09-28-04)
24.2.17
Register
Address
5Fh
60h
61h
Temperature
Below Fan Temp Limit: Fan is off or at Fan PWM
/Write
Minimum depending on bit[7:5] of register 62h
Read
R/W
R/W
R/W
Registers 5F-61h: Zone Temperature Range, PWM 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 Low 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 by the auto fan control logic.
When the temperature reaches the temperature value programmed in the Zone x Low Temp Limit
register, the PWM output assigned to that zone is at PWMx Minimum Duty Cycle. Between Zone x
Low Temp Limit and (Zone x Low Temp Limit + Zone x Range), the PWM duty cycle increases linearly
according to the temperature as shown in the figure below.
Example for PWM1 assigned to Zone 1:
■
■
■
In this case, the PWM1 duty cycle will be 50% at 50 ° C.
Zone 1 Low Temp Limit (Register 67h) is set to 50 ° C (32h).
Zone 1 Range (Register 5Fh) is set to 8 ° C (7h)
PWM1 Minimum Duty Cycle (Register 64h) is set to 50% (80h)
Zone 1 Range / Fan 1 Frequency
Zone 2 Range / Fan 2 Frequency
Zone 3 Range / Fan 3 Frequency
and bit 2 of register 7Fh
SPIN[2:0]
Register Name
000
001
010
011
100
101
110
111
Figure 24.1 Fan Activity Above Fan Temp Limit
Table 24.8 Fan Spin-Up Register
output at MIN FAN SPEED
Temperature LIMIT: PWM
(MSb)
RAN3
RAN3
RAN3
Bit 7
DATASHEET
LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
RAN2
RAN2
RAN2
244
Bit 6
RAN1
RAN1
RAN1
Bit 5
PWM Duty is linear over
RAN0
RAN0
RAN0
Bit 4
this range
FRQ3
FRQ3
FRQ3
250ms (default)
Bit 3
SPIN UP TIME
1000ms
2000ms
4000ms
100ms
400ms
700ms
0 sec
FRQ2
FRQ2
FRQ2
Bit 2
LIMIT+ RANGE: PWM
Output at 100% Duty
FRQ1
FRQ1
FRQ1
Bit 1
SMSC SCH311X
FRQ0
FRQ0
FRQ0
(LSb)
Bit 0
Datasheet
Default
Value
CBh
CBh
CBh