Dual RPM-Based PWM Fan Controller with Hardware Thermal Shutdown
Datasheet
B.3
Example #3
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
Table B.8 while Table B.9 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 else incorrect settings may be selected.
Table B.8 Look Up Table Example #3 Configuration
ADDR
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
SETTING
EN_
ALGO
Fan 1
Configuration
1
RANGE[1:0]
EDGES[1:0]
UPDATE[2:0]
1
42h
46h
50h
CBh
1
1
0
0
0
1
0
0
1
DRIVE_FAIL_CNT
1 [1:0]
NOKICK
1
SPINUP_TIME
[1:0]
Fan 1 Spin
Up
Configuration
SPIN_LVL[2:0]
1
0Ah
EAh
0
0
0
1
0
USE_D
TS_F1
USE_D LUT_LO
TACH /
DRIVE
TEMP3_CFG
[1:0]
TEMP4_CFG
[1:0]
LUT 1
Configuration
TS_F2
CK
1
1
1
0
1
0
1
0
Table B.9 Fan Speed Control Table Example #3
EXTERNAL
FAN
SPEED
STEP #
EXTERNALDIODE
1 TEMPERATURE
(CPU)
DIODE 2
TEMPERATURE
(GPU)
PUSHED
TEMPERATURE
SETTING (DTS1)
PUSHED
TEMPERATURE
SETTING (DTS2)
TACH
TARGET
3Dh
(1007 RPM)
1
2
3
4
5
6
35oC
40oC
50oC
60oC
70oC
80oC
65oC
75oC
85oC
90oC
95oC
100oC
50oC
55oC
60oC
65oC
70oC
75oC
40oC
45oC
50oC
55oC
60oC
65oC
1Eh
(2048 RPM)
14h
(3072 RPM)
0Fh
(4096 RPM)
0Ch
(5120 RPM)
0Ah
(6144 RPM)
SMSC EMC2104
Revision 1.74 (05-08-08)
DATA9S5HEET
SMSC [ SMSC CORPORATION ]
