SMBus Fan Control with 1°C Accurate Temperature Monitoring
Datasheet
Table 6.21 Spin-Up Drive
SPIN_DRIVE[1:0]
1
0
SPIN UP DRIVE
0
1
1
1
0
1
50% (half drive)
75% (3/4 drive)
100% (full drive) (default)
Bit 2-0 - SPIN_TIME[2:0] - determines the length of time that the fan drive will remain at the
SPIN_DRIVE[1:0] setting as shown in Table 6.22.
Table 6.22 Spin-Up Time
SPIN_TIME[2:0]
2
1
0
SPIN UP TIME
0 - Spin-Up Cycle bypassed
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0.05 sec.
0.1 sec.
0.2 sec.
0.4 sec.
0.8 sec.
1.6 sec.
3.2 sec. (default)
6.18
Fan Setting Register
Table 6.23 Fan Setting Register
ADDR.
R/W
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
DEFAULT
R/W
(see
text)
4Ch
Fan Setting
-
-
32
16
8
4
2
1
00h
The Fan Setting Register drives the fan driver when the Fan Control Look-Up Table is not used (see
Section 6.16). Any data written to the Fan Setting registers is applied immediately to the fan driver
(PWM or DAC). When the Fan Control Look-Up Table is being used, any writes to this register will be
ignored. If the Fan Control Look-Up Table is disabled, then the fan drive will be set at the last value
that was used by the Fan Control Look-Up Table.
When the Fan Control Look-Up Table Registers are being used, the register is read-only.
The register applies to the fan driver in both PWM and DAC operating modes. The DAC output is
determined by equation [4] below.
Revision 2.53 (03-13-07)
SMSC EMC2101
DATA4S2HEET
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