FAN5608_06 Datasheet, PDF (7/13 Pages) Fairchild Semiconductor – Serial / Parallel LED Driver with Current-Regulated, Step-Up DC/DC Converter

PWM Control
Figure 8. A is PWM controlled; B is LOW; I_LED (average) – s x 5mA, where s is the duty cycle⁽⁵⁾
A Input
B Input (PWM)
30%
Duty Cycle
1KHz
70%
Duty Cycle
1KHz
ILED
0mA
OFF
Figure 9. A is HIGH and B is PWM controlled; I_LED (average) – s x 15mA +5mA, where s is the duty cycle⁽⁶⁾
A Input (PWM)
30%
Duty Cycle
1KHz
70%
Duty Cycle
1KHz
B Input (PWM)
30%
Duty Cycle
1KHz
70%
Duty Cycle
1KHz
ILED
0mA
OFF
Figure 10. A and B are PWM controlled; I_LED (average) – s x 20mA, where s is the duty cycle⁽⁷⁾
Notes:
5. Proportionally select the duty cycle to achieve a typical LED current from 1mA to 4mA.
6. Maximum PWM frequency can be 30KHz.
7. Proportionally select the duty cycle to achieve a typical LED current from 1mA to 19mA.
© 2006 Fairchild Semiconductor Corporation
FAN5608 Rev. 1.0.5 • 8/8/06
7
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