AMC7110/1/3/4

Copyright

© 2007 ADDtek Corp.

4

DD028_F

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JUNE 2007

APPLICATION INFORMATION

Enable

The EN pin enables and disables the device. Pulling the EN pin high will enable the device beginning sink

This pin should not be left floating and need to be terminated.

LED Brightness Control

The LED sink current was fixed at 20mA or 15mA. Apply PWM signal to EN pin and control the duty that could

control the LED brightness from 0% to maximum.

Li-Ion

Battery

EN

VDD

GND

LED2

LED1

LED4

PWM Signal

Supply Voltage and Li-ion battery low warning

AMC711X works with supply voltage range from 2.7V to 6V. The white/blue LED forward voltage is in the range

of 2.9V to 3.5V at 20mA current. The supply voltage range and LED forward voltage (Vf) should be set to fully ultilize

Li-ion battery energy. For example, the maximum white LED forward voltage limit at 3.2V (@ 20mA) when Li-ion

battery discharg reaches 3.275V( normally around 1% ~ 3% power left in the battery). When Li-ion battery voltage is

lower than the presetted low level, the LED current(brightness) will start to decrease.

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:

Where, Vf is the forward voltage of LED.