BL8580/1 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
Due to its uniquely designed current regulator,
BL8580/1 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
BL8580/1’s LEDn output. This can be
accomplished by applying a PWM signal to
the EN pin. In BL8580/1, the internal power
on sequence presents a delay time of 6us
from EN pin to LEDn pin. Hence, In order to
normally modulate the output of LEDn in
every cycle, the width of dimming signal
applied EN 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.