RPM-Based PWM Fan Controller
Datasheet
PWM Frequency vs. Ambient Temperature
DD = 3.3V, Base Frequncy = 26Khz
PWM Frequency vs. Supply Voltage
TA = 25C, Base Frequncy = 26Khz
V
27000
26800
26600
26400
26200
26000
25800
25600
25400
25200
25000
27000
26800
26600
26400
26200
26000
25800
25600
25400
25200
25000
2.95
3.05
3.15
3.25
3.35
3.45
3.55
3.65
-50
0
50
100
150
Temperature (C)
Ambient Temperature (°C)
Supply Voltage (V)
FSC Algorithm Spin Up Routine – NoKick
FSC Algorithm Spin Up Routine
Spin Time = 1.0s; Spin Level = 50%; UpdateTime = 200ms;
RPM Target from 0 RPM -> 8000 RPM @ time t = 0
Spin Time = 1.0s; Spin Level = 55%; Updated Time = 200ms;
RPM Target from 0 RPM -> 8000 RPM @ time t = 0
PWM
Output
PWM
Output
10x
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PWM
10x
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PWM
Output
Output
Duty Cycle Measured = 50%
t = 0
Duty Cycle Measured = 53.8%
t = 0
FSC Algorithm PWM Ramping
Update Time = 200ms; Max Step = 16 PWM counts
RPM Target from 0 RPM -> 8000 RPM @ time t = 0
PWM
Output
10x
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PWM
Output
Spin Up Routine Ends – begins normal
operation
Duty Cycle
Measured
Update Time ends, PWM duty
cycle changed
Update Time ends, PWM duty cycle changed
Revision 1.1 (10-12-09)
SMSC EMC2301
DATA4S0HEET
SMSC [ SMSC CORPORATION ]
