EMC2112 Datasheet, PDF (53/65 Pages) SMSC Corporation – RPM-Based Linear Fan Controller with Hardware Thermal Shutdown

RPM-Based Linear Fan Controller with Hardware Thermal Shutdown
Datasheet
Bits 4 - 2 - SPIN_LVL[2:0] - Determines the final drive level that is used by the Spin Up Routine as
shown in Table 6.36.
Table 6.36 Spin Level
SPIN_LVL[2:0]
2
1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
SPIN UP DRIVE LEVEL
0
0
30%
1
35%
0
40%
1
45%
0
50%
1
55%
0
60% (default)
1
65%
Bit 1 -0 - SPINUP_TIME[1:0] - determines the maximum Spin Time that the Spin Up Routine will run
for (see Section 5.2). If a valid tachometer measurement is not detected before the Spin Time has
elapsed, then an interrupt will be generated. When the RPM-based Fan Speed Control Algorithm is
active, the fan driver will attempt to re-start the fan immediately after the end of the last spin up attempt.
The Spin Time is set as shown in Table 6.37.
Table 6.37 Spin Time
SPINUP_TIME[1:0]
1
0
0
0
0
1
1
0
1
1
TOTAL SPIN UP TIME
250 ms
500 ms (default)
1 sec
2 sec
6.22 Fan Max Step Register
Table 6.38 Fan Max Step Register
ADDR
R/W
REGISTER
B7 B6 B5 B4 B3 B2
B1
B0
DEFAULT
47h
R/W Fan Max Step
-
-
32 16 8
4
2
1
10h
The Fan Max Step Register, along with the Update Time, controls the ramp rate of the fan driver
response calculated by the RPM-based Fan Speed Control Algorithm. The value of the registers
represents the maximum step size each fan driver will take between update times (see Section 6.18).
SMSC EMC2112
53
DATASHEET
Revision 0.88 (11-20-09)