A708 데이터 시트보기 (PDF) - ADDtek Corp
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A708 Datasheet PDF : 8 Pages
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A708
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.
VIN
CBP
VDD
CIN
Enable
LED1 LED2 LED3
VDD
A708
EN
GND
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:
Efficiency = (VF1 × ILED1 + VF2 × ILED2 + VF3 × ILED3 ) / ( VDD × IDD )
Where, VF is the forward voltage of LED.
Copyright © 2007 ADDtek Corp.
5
DD076_A -- AUGUST 2007
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