emc2106 Standard Microsystems Corp., emc2106 Datasheet - Page 78

• Manufacturer Part Number: emc2106
• Description: Emc2106 Dual Rpm-based Linear Fan Controller With Hardware Thermal Shutdown
• Manufacturer: Standard Microsystems Corp.

Revision 1.74 (05-08-08)
6.32
6.33
ADDR
ADDR
4Ch
4Dh
8Ch
8Dh
4Ah
4Bh
8Ah
8Bh
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
If the TACH Reading Register value exceeds the Valid TACH Count Register (indicating that the Fan
RPM is below the threshold set by this count), then a stalled fan is detected. In this condition, the
algorithm will automatically begin its Spin Up Routine.
If a TACH Target setting is set above the Valid TACH Count setting, then that setting will be ignored
and the algorithm will use the current fan drive setting.
The Valid TACH Count Register is software locked.
The Fan Drive Fail Band Registers store the number of tach counts used by the Fan Drive Fail
detection circuitry. This circuitry is activated when the fan drive setting high byte is at FFh. When it is
enabled, the actual measured fan speed is compared against the target fan speed. These registers
are only used when the FSC is active.
This circuitry is used to indicate that the target fan speed at full drive is higher than the fan is actually
capable of reaching. If the measured fan speed does not exceed the target fan speed minus the Fan
Drive Fail Band Register settings for a period of time longer than set by the DRIVE_FAIL_CNTx[1:0]
bits then the DRIVE_FAIL status bit will be set and an interrupt generated.
Fan Drive Fail Band Registers
TACH Target Registers
R
TACH Target
TACH Target
TACH Target
TACH Target
Fan 1 Drive
Fan 2 Drive
1 High Byte
2 High Byte
REGISTER
REGISTER
1 Low Byte
2 Low Byte
Fan 1 Drive
Fan 2 Drive
High Byte
High Byte
Fail Band
Fail Band
Fail Band
Fall Band
Low Byte
Low Byte
Table 6.47 Fan Drive Fail Band Registers
4096
4096
4096
4096
Table 6.48 TACH Target Registers
B7
B7
16
16
16
16
2048
2048
2048
2048
B6
B6
DATASHEET
8
8
8
8
Dual RPM-Based Linear Fan Controller with Hardware Thermal Shutdown
1024
1024
1024
1024
B5
B5
78
4
4
4
4
512
512
512
512
B4
B4
2
2
2
2
256
256
256
256
B3
B3
1
1
1
1
128
128
128
128
B2
B2
-
-
-
-
B1
B1
64
64
64
64
-
-
-
-
B0
B0
32
32
32
32
-
-
-
-
SMSC EMC2106
DEFAULT
DEFAULT
Datasheet
F8h
FFh
F8h
FFh
00h
00h
00h
00h