EMC6D103-CK SMSC [SMSC Corporation], EMC6D103-CK Datasheet - Page 41

• Manufacturer Part Number: EMC6D103-CK
• Description: FAN CONTROL DEVICE WITH HIGH FREQUENCY PWM
• Manufacturer: SMSC [SMSC Corporation]

Fan Control Device with High Frequency PWM Support and Hardware Monitoring Features
Datasheet
SMSC EMC6D103
RRX-
[2:0]
Ramping Duty Cycle
Calculate Duty Cycle
PWM Duty Cycle
Ramping Duty Cycle
011
100
101
110
Calculate Duty Cycle
PWM Duty Cycle
111
Example 1: PWM period < Ramp Rate Step Size
PWM frequency = 87.7Hz (11.4msec) & PWM Ramp Rate = 38.46Hz (26msec)
Example 2: PWM period > Ramp Rate Step Size
PWM frequency = 11Hz (90.9msec) & PWM Ramp Rate = 38.46Hz (26msec)
Notes:
■
■
PWM RAMP TIME (SEC)
100% DUTY CYCLE)
The PWM Duty Cycle latches the Ramping Duty Cycle on the rising edge of the PWM output.
The calculated duty cycle, ramping duty cycle, and the PWM output duty cycle are asynchronous
to each other, but are all synchronized to the internal 90kHz clock source.
(TIME FROM 33%
DUTY CYCLE TO
7.0
4.4
3.0
1.6
0.8
Figure 7.4 Illustration of PWM Ramp Rate Control
70h
70h
70h
70h
70h
70h
Table 7.1 PWM Ramp Rate (continued)
11.4ms
71h
71h
71h
PWM RAMP TIME (SEC)
26ms
CYCLE TO 100% DUTY
26ms
(TIME FROM 0% DUTY
71h
DATASHEET
11.4ms
CYCLE)
71h
10.455
1.275
6.63
4.59
2.55
74h
74h
41
11.4ms
72h
72h
72h
26ms
26ms
71h
90.9msec
11.4ms
72h
11.4ms
73h
(PWM STEP SIZE =
PWM STEP
73h
TIME PER
73h
11.4ms
41 msec
26 msec
18 msec
10 msec
73h
5 msec
1/255)
11.4ms
73h
11.4ms
74h
Revision 0.4 (04-04-05)
74h
74h
11.4ms
74h
74h
RAMP
RATE
PWM
24.39
38.46
55.56
100
200
(HZ)
74h