emc2103-3-kp-tr Standard Microsystems Corp., emc2103-3-kp-tr Datasheet - Page 61

• Manufacturer Part Number: emc2103-3-kp-tr
• Description: Emc2103 Rpm-based Fan Controller With Hardware Thermal Shutdown
• Manufacturer: Standard Microsystems Corp.

RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
APPLICATION NOTE: If the Fan Speed Control Algorithm is used, the default settings in the Fan Configuration 2
SMSC EMC2103
6.26
6.27
6.28
ADDR
ADDR
ADDR
48h
47h
49h
R/W
R/W
R/W
R/W
R/W
R/W
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
setting that will maintain fan operation is a useful way to avoid potential fan oscillations as the control
circuitry attempts to drive it at a level that cannot support fan operation.
The Fan Minimum Drive Register is software locked.
The Valid TACH Count Register store the maximum TACH Reading Register value to indicate that the
the fan is spinning properly. The value is referenced at the end of the Spin Up Routine to determine
if the fan has started operating and decide if the device needs to retry.
Fan Step Register
Fan Minimum Drive Register
Valid TACH Count Register
REGISTER
Valid TACH
Fan Minimum
REGISTER
Fan Max Step
Count
REGISTER
Register will cause the maximum fan step settings to be ignored.
Section
Drive
Section
6.22).
4096
Table 6.44 Minimum Fan Drive Register
B7
Table 6.45 Valid TACH Count Register
128
B7
6.30)
B7
-
Table 6.43 Fan Step Register
2048
B6
B6
64
B6
DATASHEET
-
1024
B5
B5
32
B5
61
32
512
B4
B4
16
B4
16
256
B3
B3
B3
8
8
128
B2
B2
B2
4
4
B1
64
B1
B1
2
2
Revision 0.88 (06-30-08)
B0
B0
32
B0
1
1
DEFAULT
DEFAULT
DEFAULT
(40%)
F5h
66h
10h