a708ygt ADD Microtech Inc., a708ygt Datasheet - Page 5

• Manufacturer Part Number: a708ygt
• Description: 3 Channels 20ma Advanced Current Regulator
• Manufacturer: ADD Microtech Inc.

Enable
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 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 brightness from 0% to maximum.
Efficiency
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:
Copyright © 2008 ADDtek Corp.
The ACR (Advanced Current Regulator) architecture offers ultra low output dropout that significantly improves
Pulling the EN pin to high will enable the device sinking constant current on LED pins. Pulling the EN pin to
The breakdown voltage of LEDn pin is 17V so that each channel can drive up to 9 pcs of LEDs in series. When
The LED sink current was fixed at 20mA. Apply PWM signal to EN pin and control the duty that could control
Efficiency = (V
Where, V
F
is the forward voltage of LED.
F1
× I
LED1
+ V
F2
APPLICATION INFORMATION
× I
LED2
Enable
+ V
V
V
IN
DD
F3
C
BP
C
× I
IN
5
LED3
) / ( V
EN
VDD
LED1
DD
× I
LED2
A708
GND
DD
)
LED3
DD076_C -- OCTOBER 2008
A708