FAN5608 Fairchild Semiconductor, FAN5608 Datasheet - Page 7

• Manufacturer Part Number: FAN5608
• Description: Serial/Parallel LED Driver with Current-Regulated/ Step-Up DC/DC Converter
• Manufacturer: Fairchild Semiconductor

FAN5608
PWM Control
1. A is PWM Controlled, B is Low. I
2. A is High and B is PWM. I
3. A and B are PWM. I
Notes:
3. Proportionally select the duty cycle to achieve a typical LED current between 1mA to 4mA.
4. Maximum PWM frequency can be 30KHz.
5. Proportionally select the duty cycle to achieve a typical LED current between 1mA and 19mA.
REV. 1.0.3 6/28/04
A Input (PWM)
B Input (PWM)
A Input
B Input (PWM)
I LED
A Input (PWM)
B Input (0)
I LED
I LED
0mA
0mA
LED
0mA
(Average) =
LED
Duty Cycle
I
1KHz
LED
30%
Duty Cycle
Duty Cycle
Duty Cycle
1KHz
30%
(Average) = 5mA +
1KHz
1KHz
(Average) = 0.3 x 20mA + 0.7 x 5mA = 9.5mA
30%
30%
I
LED
I
LED
LED
(Average) = 0.3 x 5mA = 1.5mA
δ
(Average) = 0.3 x 20mA = 6mA
x 20mA, where
(Average) =
δ
δ
x 15mA, where
x 5mA, where
δ
is Duty Cycle. (Note 5)
δ
I
δ
LED
is Duty Cycle. (Note 3)
Duty Cycle
is Duty Cycle. (Note 4)
1KHz
70%
(Average) = 0.7 x 20mA + 0.3 x 5mA = 15.5mA
Duty Cycle
I
LED
1KHz
70%
I
LED
Duty Cycle
Duty Cycle
(Average) = 0.7 x 5mA = 3.5mA
1KHz
1KHz
70%
70%
(Average) = 0.7 x 20mA = 14mA
OFF
PRODUCT SPECIFICATION
OFF
OFF
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