EMC2103 Standard Microsystems Corporation, EMC2103 Datasheet - Page 60

• Manufacturer Part Number: EMC2103
• Description: Rpm-based Fan Controller with HW Thermal Shutdown
• Manufacturer: Standard Microsystems Corporation

APPLICATION NOTE: If the Fan Speed Control Algorithm is used, the default settings in the Fan Configuration 2
Revision 0.85 (01-29-08)
6.26
6.27
ADDR
ADDR
48h
47h
R/W
R/W
R/W
R/W
The Fan Spin Up Configuration Register is software locked.
The Fan Step Register, along with the Update Time, control the ramp rate of the fan driver response.
The value of the registers represents the maximum step size each fan driver will take between update
times (see
All modes of operation have the options to use the Fan Step Register (and update times) for ramp rate
control based on the Fan Configuration 2 Register settings. The Fan Speed Control Algorithm will
always use the Fan Step Register settings (but see application note below).
The Fan Step Register is software locked.
The Fan Minimum Drive Register stores the minimum drive setting for the RPM based Fan Speed
Control Algorithm. This register is not used if the FSC is not active. The RPM based Fan Speed Control
Algorithm will not drive the fan at a level lower than the minimum drive unless the target TACH Target
is set at FFh (see
During normal operation, if the fan stops for any reason (including low drive), the RPM based Fan
Speed Control Algorithm will attempt to restart the fan. Setting the Fan Minimum Drive Registers to a
Fan Step Register
Fan Minimum Drive Register
1
0
0
1
1
Fan Minimum
REGISTER
Fan Max Step
REGISTER
Register will cause the maximum fan step settings to be ignored.
Section
Drive
SPINUP_TIME[1:0]
Section
6.22).
Table 6.43 Minimum Fan Drive Register
128
B7
6.30)
B7
-
Table 6.42 Fan Step Register
Table 6.41 Spin Time
B6
64
B6
DATASHEET
-
B5
32
B5
60
32
0
0
1
0
1
B4
16
B4
16
RPM-Based Fan Controller with HW Thermal Shutdown
B3
B3
8
8
B2
B2
4
4
TOTAL SPIN UP TIME
B1
B1
2
2
500 ms (default)
250 ms
B0
B0
1 sec
2 sec
1
1
SMSC EMC2103
DEFAULT
DEFAULT
(40%)
Datasheet
66h
10h