RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown
Datasheet
Table A.7 Fan Speed Determination for Example #2 (using settings in Table A.6)
EXTERNAL
DIODE 1
TEMPERATURE TEMPERATURE
EXTERNAL
DIODE 2
PUSHED
TEMPERATURE
(DTS1)
PUSHED
TEMPERATURE
(DTS2)
(CPU)
(GPU)
PWM RESULT
52h (2997 RPM) -
CPU requires highest
target
35°C
50°C
Example 1:
Example 2:
75°C
75°C
(translated as 65°C) (translated as 50°C)
15°C
20°C
29h (5994 RPM) -
DTS1 requires
highest target
75°C
75°C
90°C
(translated as
(translated as 80°C)
85°C)
5°C
31h (5016 RPM) -
DTS2 requires
highest target
30°C
Example 3:
97.25°C
(translated as
(translated as 70°C)
95°C)
A.3
Example #3
This example uses the RPM-based Fan Speed Control Algorithm with default settings.
For control inputs, it uses the External Diode 1 channel normally, the External Diode 2 channel
normally, the PWM input instead of External Diode 3, and the Internal Diode. The configuration is set
as shown in Table A.8 while Table A.9 shows how the table is loaded.
Table A.8 Look Up Table Example #3 Configuration
ADDR
REGISTER
B7
B6
B5
B4
B3
B2
B1
B0
SETTING
USE_
DTS_F1
USE_
DTS_F2
LUT_
LOCK
RPM /
PWM
PUSH1_ TEMP1_ TEMP3_ TEMP4_
LUT
Configuration
CFG
1
CFG
0
CFG
1
CFG
0
90h
2Ah
0
0
1
0
A.3.1
LUT COnfiguration Bit Description
Bit 7 - USE_DTS_F1 = ‘0b’ tells the circuitry that the Forced Temperature 1 register data is not in DTS
format.
Bit 6 - USE_DTS_F2 = ‘0b’ tells the circuitry that the Forced Temperature 2 register data is not in DTS
format.
Bit 5 - LUT_LOCK = ‘1b’ tells the circuitry that the LUT is programmed and is active. This bit must be
set for the LUT to function.
Bit 4 - RPM_PWM = ‘0b’ tells the LUT circuitry that the FSC algorithm is active and that the LUT values
are TACH Target settings. This is the default setting.
Bit 3 - PUSH1_CFG = ‘1b’ tells the Look Up Table to reference the PWM Input Duty Cycle instead of
the Pushed Temperature 1 register.
Bit 2 - TEMP1_CFG = ‘0b’ tells the LUT to reference the External Diode 1 data instead of Forced
Temperature 1 data. This is the default setting.
Revision 1.2 (10-08-09)
SMSC EMC2113
DATA8S4HEET
SMSC [ SMSC CORPORATION ]
