RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown
Datasheet
Bit 1 - TEMP3_CFG = ‘1b’ tells the Look Up Table to reference Pushed Temperature 1 instead of
External Diode 3, except that PUSH1_CFG re-directs the logic to reference the PWM Input Duty Cycle
register instead.
Bit 0 - TEMP4_CFG = ‘0b’ tells the LUT to reference the Internal Diode data instead of Forced
Temperature 2 data. This is the default setting.
Table A.9 Fan Speed Control Table Example #3
EXTERNAL
DIODE 1
TEMPERATURE
EXTERNAL
DIODE 2
TEMPERATURE
FAN
SPEED
STEP #
PWM DUTY
CYCLE
TACH
TARGET
(CPU)
(GPU)
INTERNAL DIODE
20% Duty Cycle
(1Ah)
EFh
(1028 RPM)
1
2
3
4
5
6
7
8
35oC
40oC
50oC
60oC
70oC
80oC
90oC
100oC
65oC
75oC
40oC
30% Duty Cycle
(26h)
A3h
(1508 RPM)
45oC
50oC
55oC
60oC
65oC
80oC
100oC
40% Duty Cycle
(33h)
7Ah
(2014 RPM)
85oC
50% Duty Cycle
(40h)
62h
(2508 RPM)
90oC
60% Duty Cycle
(4Dh)
52h
(2997 RPM)
95oC
70% Duty Cycle
(5Ah)
3Dh
(4029 RPM)
100oC
105oC
110oC
80% Duty Cycle
(66h)
31h
(5016 RPM)
90% Duty Cycle
(73h)
29h
(5994 RPM)
Note: The values shown in Table A.9 are example settings. All the cells in the look-up table are
programmable via SMBus.
Table A.10 Fan Speed Determination for Example #2 (using settings in Table A.9)
EXTERNAL
DIODE 1
EXTERNAL
DIODE 2
TEMPERATURE TEMPERATURE PWM INPUT DUTY
(CPU)
(GPU)
CYCLE
INTERNAL DIODE
PWM RESULT
52h (2997 RPM) -
CPU requires highest
target
Example 1:
Example 2:
Example 3:
75°C
45% Duty Cycle
50°C
75°C
31h (5016 RPM) -
PWM requires highest
target
75°C
75°C
90°C
70°C
85% Duty Cycle
31h (5016 RPM) -
DTS2 requires
highest target
97.25°C
75% Duty Cycle
95°C
SMSC EMC2113
Revision 1.2 (10-08-09)
DATA8S5HEET
SMSC [ SMSC CORPORATION ]
