FAN5609 Fairchild Semiconductor, FAN5609 Datasheet - Page 6

• Manufacturer Part Number: FAN5609
• Description: LED Driver with Adaptive Charge Pump DC/DC Converter
• Manufacturer: Fairchild Semiconductor

FAN5609
Digital Control with PWM
A is PWM and B is Low.
A is High and B is PWM.
Notes:
2. Proportionally select the duty cycle to achieve a typical LED current between 1mA to 6mA.
3. If either input A or B is continuously high, the other input can be modulated at a maximum rate of 30kHz. Otherwise the
4. Proportionally select the duty cycle to achieve a typical LED current between 8mA to 19mA.
6
maximum rate of modulation should be limited to 1kHz.
A Input
B Input (PWM)
I LED
A Input (PWM)
B Input (0)
I LED
0mA
0mA
I
LED
I
LED
(Average) =
Duty Cycle
Duty Cycle
(Average) = 6mA +
1KHz
30%
1KHz
30%
I
LED
(Average) = 7mA + 0.3 x 14mA = 11.2mA
I
LED
(Average) = 0.3 x 7mA = 2.1mA
δ
x 7mA, where
δ
x 12mA, where
δ
is Duty Cycle. (Note 2)
I
LED
δ
is Duty Cycle. (Note 3, 4)
(Average) = 7mA +
I
Duty Cycle
LED
Duty Cycle
1KHz
70%
1KHz
70%
(Average) = 0.7 x 7mA = 4.9mA
0.7 x 14mA = 16.8mA
PRODUCT SPECIFICATION
REV. 1.0.2 5/30/03
OFF
OFF