August , 2011, REV1.0
BCT3228 preliminary
8 Channel LED Driver (Common-Anode & Common-Cathode)
Low Dropout Current Source & Current Sink
General Description
The BCT3228 is a high performance 8 channel
white LED driver. The BCT3228 uses two
internal resistor to set the bias current for four
LEDs. The BCT3228's advantages over ballast
resistors include much lower bias variation with
supply voltage variation, significantly lower
dropout voltage, and in some applications,
significantly improved efficiency. The BCT3228
requires only a 50mV dropout voltage at a
20mA load on each output to match the LED
brightness.
By using two SEL pin, the BCT3228 can
support to drive 8 parallel Co-Anode or
Co-Cathode white LEDs and regulates a
constant current for uniform intensity.
Users can easily configure the LED current
from 2.5mA to 20mA by a serial pulse. The
dimming of white LEDs current can be
achieved by applying a pulse signal to the EN
pin. There are totally 8 steps of current could be
set by users. Internal soft start circuitry
effectively reduces the in-rush current while
both start-up and mode transition.
Features
♦ Drive Common Anode or Common
Cathode LEDs
♦ Low 50mV Dropout at 20mA
♦ 20mA full scale current
♦ One Wire interface for 8-Step Brightness
Control
♦ 2.7V to 5.5V Supply Voltage Range
♦ Thermal Shutdown Protection
♦ Low Input Noise and EMI
♦ RoHS Compliant and 100% Lead
(Pb)-Free, QFN-24L Package
Applications
Cell Phones
PDAs
Digital Cameras, Camcorders
Portable Instrumentation
Battery Powered Equipment
Pin Configurations (Top View)
QFN4x4-24L Package
www.broadchip.com
