Multiple RPM-Based PWM Fan Controller
Datasheet
The Gain registers store the gain terms used by the proportional and integral portions of each of the
RPM-based Fan Speed Control Algorithms. These gain terms are used as the KD, KI, and KP gain
terms in a classic PID control solution.
Bits 5 - 4 - GAINDX[1:0] - Controls the derivative gain term used by the FSC algorithm as shown in
Bits 3-2 - GAINIX[1:0] - Controls the integral gain term used by the FSC algorithm as shown in
Bits 1-0 - GAINP[1:0] - Controls the proportional gain term used by the FSC algorithm as shown in
Table 5.18 Gain Decode
GAIND OR GAINP OR GAINI [1:0]
1
0
0
1
1
0
0
1
0
1
RESPECTIVE GAIN FACTOR
1x
2x
4x (default)
8x
5.12
Fan Spin Up Configuration Registers
Table 5.19 Fan Spin Up Configuration Registers
ADDR
36h
46h
56h
R/W
R/W
R/W
R/W
REGISTER
Fan 1 Spin Up
Configuration
Fan 2 Spin up
Configuration
Fan 3 Spin up
Configuration
B7
B6
B5
NOKICK1
NOKICK2
NOKICK3
B4
B3
B2
B1
B0
DEFAULT
19h
19h
19h
DRIVE_FAIL_
CNT1 [1:0]
DRIVE_FAIL_
CNT2 [1:0]
DRIVE_FAIL_
CNT3 [1:0]
SPIN_LVL1[2:0]
SPIN_LVL2[2:0]
SPIN_LVL3[2:0]
SPINUP_TIME
1 [1:0]
SPINUP_TIME
2 [1:0]
SPINUP_TIME
3[1:0]
The Fan Spin Up Configuration registers control the settings of Spin Up Routine. The Fan Spin Up
Configuration registers are software locked.
Bit 7 - 6 - DRIVE_FAIL_CNTx[1:0] - Determines how many update cycles are used for the Drive Fail
detection function as shown in
This circuitry determines whether the fan can be driven to
the desired tach target.
SMSC EMC2303
37
Revision 1.1 (10-12-09)
DATASHEET
SMSC [ SMSC CORPORATION ]
