A708

Copyright

© 2007 ADDtek Corp.

5

DD076_A

--

AUGUST 2007

APPLICATION INFORMATION

Enable

Pulling the EN pin to high will enable the device sinking constant current on LED pins. Pulling the EN pin to

ground will shutdown the device. This pin should not be left floating and need to be terminated.

LED Number in the String Driven by Each Channel

The breakdown voltage of LEDn pin is 17V so that each channel can drive up to 9 pcs of LEDs in series. When

the chip is disabled, the forward voltage of the LED may drop to half of the rated value because of the extremely small

leakage current.

LED Brightness Control

The LED sink current was fixed at 20mA. Apply PWM signal to EN pin and control the duty that could control

the LED brightness from 0% to maximum.

Enable

A708

EN

LED2

VDD

GND

LED1

LED3

Efficiency

The ACR (Advanced Current Regulator) architecture offers ultra low output dropout that significantly improves

the efficiency compared to Inductive Boost type or Capacitor Charge Pump type LED driver. The system efficiency,

defined as the ratio between the LEDs power and the input supplied power, is: