EMC2305_11 Datasheet, PDF (40/56 Pages) SMSC Corporation – Multiple RPM-Based PWM Fan Controller for Five Fans

5.11
Multiple RPM-Based PWM Fan Controller for Five Fans
Datasheet
drive setting is not updated. The algorithm will continue to monitor the fan speed and calculate
necessary drive setting changes based on the error; however, these changes are ignored.
Table 5.16 Error Range Options
ERR_RNGX[1:0]
1
0
0
0
0
1
1
0
1
1
OPERATION
0 RPM (default)
50 RPM
100 RPM
200 RPM
Gain Registers
ADDR R/W
35h
R/W
45h
R/W
55h
R/W
65h
R/W
75h
R/W
REGISTER
Gain 1
Register
Gain 2
Register
Gain 3
Register
Gain 4
Register
Gain 5
Register
Table 5.17 Gain Registers
B7
B6 B5
B4
B3
B2 B1 B0 DEFAULT
-
-
GAIND1[1:0] GAINI1[1:0] GAINP1[1:0]
2Ah
-
-
GAIND2[1:0] GAINI2[1:0] GAINP2[1:0]
2Ah
-
-
GAIND3[1:0] GAINI3[1:0] GAINP3[1:0]
2Ah
-
-
GAIND4[1:0] GAINI4[1:0] GAINP4[1:0]
2Ah
-
-
GAIND5[1:0] GAINI5[1:0] GAINP5[1:0]
2Ah
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
Table 5.18.
Bits 3-2 - GAINIX[1:0] - Controls the integral gain term used by the FSC algorithm as shown in
Table 5.18.
Bits 1-0 - GAINP[1:0] - Controls the proportional gain term used by the FSC algorithm as shown in
Table 5.18.
Revision 1.3 (05-18-11)
40
DATASHEET
SMSC EMC2305