A8131
LED BACKLIGHT DRIVER
AiT Semiconductor Inc.
www.ait-ic.com
PWM/PFM AUTOMATIC CONTROLLED DC-DC CONVERTERS
TYPICAL APPLICATION
Figure 1 Typical application circuit
Figure 2 Typical application circuits with PWM dimming signal
Calculate ILED using the following equations
0.1−
R1x(VPWM x DUTY − 0.1)
(R2 +R3)
I
LED =
RSET
Where VPWM is the amplitude of PWM signal.
For example, for 3.3V VPWM, R1=4.7k, R2=100k, R3=47k.
The value of C3 depends on the frequency of PWM dimming; an empirical suggestion is around 0.1uF for
MHz and 10uF for low frequency under kHz.
REV1.1
- JAN 2014 RELEASED, AUG 2017 UPDATED -
- 6 -
AITSEMI [ AiT Semiconductor ]
