RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
A.2
Example #2
This example uses the RPM based Fan Speed Control Algorithm. The Spin Level (used by the Spin
Up Routine) should be changed to 50% drive for a total Spin Time of 1 second. For all other RPM
configuration settings, the default conditions are used.
For control inputs, it uses the External Diode 1 channel normally, the External Diode 2 channel
normally, and both Pushed Temperature registers in DTS format. The configuration is set as shown in
while
shows how the table is loaded.
Note that when using DTS data, the USE_DTS_F1 and / or USE_DTS_F2 bits should be set. The
Pushed Temperature Registers are loaded with the normal DTS values as received by the processor.
When the DTS value is used by the Look Up Table, the value that is stored in the Pushed Temperature
Register is subtracted from a fixed temperature of 100°C. This resultant value is then compared
against the Look Up Table thresholds normally. When programming the Look Up Table, it is necessary
to take this translation into account or else incorrect settings may be selected.
Table A.5 Look Up Table Example #2 Configuration
ADDR
REGISTER
Fan 1
Configuration
1
Fan 1 Spin
Up
Configuration
B7
EN_
ALGO
1
B6
B5
B4
B3
B2
B1
UPDATE[2:0]
CBh
1
0
NOKICK
1
0
LUT_LO
CK
1
0
RPM /
PWM
0
0
1
SPIN_LVL[2:0]
1
-
0
0
TEMP3
_CFG
1
0
0
1
1
B0
SETTING
RANGE[1:0]
EDGES[1:0]
42h
46h
DRIVE_FAIL_CNT1
[1:0]
0
USE_DT
S_F1
1
0
USE_D
TS_F2
1
SPINUP_TIME
[1:0]
1
0
TEMP
3_CFG
1
0Ah
50h
LUT 1
Configuration
E5h
Table A.6 Fan Speed Control Table Example #2
EXTERNAL
DIODE 1
TEMPERATURE
(CPU)
35
o
C
40
o
C
50
o
C
60
o
C
70
o
C
80
o
C
EXTERNAL
DIODE 2
TEMPERATURE
(GPU)
65
o
C
75
o
C
85
o
C
90
o
C
95
o
C
100
o
C
FAN
SPEED
STEP #
1
2
3
4
5
6
PUSHED
TEMPERATURE
SETTING (DTS1)
50
o
C
55
o
C
60
o
C
65
o
C
70
o
C
75
o
C
PUSHED
TEMPERATURE
SETTING (DTS2)
40
o
C
45
o
C
50
o
C
55
o
C
60
o
C
65
o
C
TACH
TARGET
3Dh
(1007 RPM)
1Eh
(2048 RPM)
14h
(3072 RPM)
0Fh
(4096 RPM)
0Ch
(5120 RPM)
0Ah
(6144 RPM)
SMSC EMC2103
Revision 0.85 (01-29-08)
78
DATASHEET
SMSC [ SMSC CORPORATION ]
