ANALOG PRODUCTS DIVISION

561 E. Elliot Road #175 Chandler, AZ 85225 Tel: (480) 539-2900. Fax: (480) 632-1715

www.protekanalog.com

8

PA5910

Switching Type LED Driver.

95220 Rev.0. 04/09

NOT FOR USE IN LIFE SUPPORT SYSTEMS

Setting LED Output

When the buck converter topology is used, the peak current sense (CS) is a good representation of the average

current of the LED. There is a certain error associated with this CS method that needs to be accounted for. The

error is introduced by the difference between the the peak and average current in the inductor:

L

L

CS

I

I

mV

R

Δ

+

=

5

.

0

250

e.g. If the peak-to-peak ripple current in the inductor is 10.5mA, to maintain a 350mA LED current, the sense

LED Brightness.

There are two methods of adjusting the brightness of the LED’s.

2. PWM dimming. The brightness of the LED’s is controlled by varying the duty ratio of the output current.

This is achieved by applying a PWM signal at the EN (pin 2).