ACE517 Datasheet, PDF (4/8 Pages) ACE Technology Co., LTD. – WLED Linear Driver for Li-lon Battery Application

Technology
Typical Application Circuit
Li-Ion Battery
ACE517
WLED Linear Driver for Li-lon Battery Application
On/Off Control
VCC
GND
LED 1
LED 2
LED 3
EN
LED 4
Only Available in ACE517
Detailed Description
ACE517 works with a wide range of supply voltage, from 2.7V to 6V. The forward voltage of commercial
white/blue LED is in the range of 2.9V to 3.5V at a current level of 20mA. Proper selection of the LED to
match the supply voltage can fully utilize the Li-ion battery. For example, there is 1% ~ 3% power left in
the Li-ion battery when its voltage reaches 3.275V. So a LED with a forward voltage value of 3.2V can use
up to 99% of the battery power under normal working condition. When the voltage of the battery drops
below 3.2V, the current through the LED (hence the brightness) starts to decrease.
Due to its uniquely designed current regulator, ACE517 offer low output dropout and provide superior
efficiency performance over standard inductive boost type and capacitive charge pump type LED driver.
The EN pin controls the on/off state of the device. A high level state turns on the device and a low level
turns off the device, results in the low off state current. This pin needs to be terminated since a floating
level of the EN pin will cause the instability of the device.
The sink current has a constant value of 20mA. The brightness of the LED can be adjusted by controlling
the duty cycle of the ACE517 LEDn pin. Hence, in order to normally modulate the output of LEDn in every
cycle, the width of dimming signal applied CE pin have to be no less than 6us. For example, when a
dimming signal of 20KHz is applied, the minimum range of dimming is about 12%, that is , the average
output current on each channel is 2.4mA.
VER 1.2 4