BCT3220
4 Channel LED Driver (Common-Anode & Common-Cathode)
Low Dropout Current Source & Current Sink
General Description
The BCT3220 is a high performance white
LED driver. The BCT3220 uses an internal
resistor to set the bias current for four LEDs,
which are matched to +/-1.5%. The BCT3220'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 BCT3220 requires
only a 50mV dropout voltage at a 20mA load on
each output to match the LED brightness.
By using one SEL pin, the BCT3220 can
support to drive 4 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
♦ <2% LED Current Matching (TYP)
♦ 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, DFN-8L Package
Applications
Cell Phones
PDAs
Digital Cameras, Camcorders
Portable Instrumentation
Battery Powered Equipment
Pin Configurations
(Top View)
DFN2x2-8L Package
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4 Channel LED Driver (Common-Anode & Common-Cathode)
Ordering Information
PART
BCT3220ELA-TR
PIN-PACKAGE
DFN2x2-8L
Temp-Range
-40° to +85°
C
C
Top Mark
BCT3220
Supplied as:
3000units/Tape & Reel
Functional Pin Description
Pin
1
2
3
4
5
6
7
8
Name
D1
D2
D3
D4
GND
SEL
EN
VIN
Function
LED Pin1, leave it NC if unused.
LED Pin2, leave it NC if unused.
LED Pin3, leave it NC if unused.
LED Pin4, leave it NC if unused.
Ground
When SEL is Low, it’s a Co-Anode LED driver (see Figure 1).
When SEL is High, it’s a Co-Cathode LED driver (see Figure 2).
Chip Enable (Active High), and connects to GPIO pin of MCU.
Input voltage
Typical Application Circuit
Figure 1: Application Circuit for Co-Anode Connection.
www.broadchip.com
4 Channel LED Driver (Common-Anode & Common-Cathode)
Figure 2: Application Circuit for Co-Cathode Connection.
Figure 3: Application Circuit for Co-Anode & Co-Cathode Connection.
www.broadchip.com
4 Channel LED Driver (Common-Anode & Common-Cathode)
ABSOLUTE MAXIMUM RATINGS
VIN to GND.........................................-0.3V to 6V
All Other Pins to GND ......-0.3V to (VCC + 0.3V)
Continuous Current (D1- D4)………...... ±30mA
Continuous Power Dissipation (TA = +70°
C)
8-Pin DFN (derate 10.5mW/° above
C
+70° ......................................................0.84W
C)
Operating Temperature
Range ..................................-40° to +85°
C
C
Storage Temperature
Range.................................-65° to +150°
C
C
Junction Temperature.......................+150°
C
Lead Temperature (soldering, 10s)...+300°
C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress
ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational
sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device
reliability.
ELECTRICAL CHARACTERISTICS
(VIN = 2.7V to 5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VIN = 3.3V, TA = +25°
C.)
PARAMETER
POWER SUPPLY
Supply Voltage
Range
Supply Current
Shut Down Current
SYMBOL CONDITIONS
MIN
TYP MAX
UNITS
VIN
I
VIN
I
SHUT
EN= high, SEL= ‘0’ or ‘1’, D_ floating
EN= low
2.7
150
5.5
200
1
V
uA
uA
Analog Outputs ( D1-D4)
Drop Out Voltage
(Current Source
mode)
Drop Out Voltage
(Current Sink mode)
Current Accuracy
Current Matching
Between Channels
Logic Inputs (EN, SEL)
Input-Logic High
Input-Logic Low
Input Leakage
Current
IC junction thermal
shutdown threshold
V
IH
V
IL
I
IN
TJ-TH
V(EN or SEL) = 0 or VIN
155
1.4
0.4
±1
V
V
uA
°
C
V
DROP1
SEL=1, ID_ = 20mA, VIN- VD_
V
DROP2
SEL=0, ID_ = 20mA, VD_ - GND
I
D_
△
I
D_
Current Source or Sinck mode
Max(△ I
D_
) /Iavg ,
Current Source or Sinck mode
18
60
55
20
1.5
80
75
22
3
mV
mV
mA
%
Note : Devices are 100% tested at TA = +25° Limits across the full temperature range are guaranteed by design and
C.
correlation.
www.broadchip.com
4 Channel LED Driver (Common-Anode & Common-Cathode)
Functional Block Diagram
Functional Description
The BCT3220 is a four-channel current sink and current source driver, offering ultra-high efficiency for
driving parallel LEDs.
When pin SEL is low, The BCT3220 enters current sink mode and can support to
drive 4 parallel Co-Anode LEDs, when pin SEL is high, The BCT3220 enters current source mode
and can drive 4 Co-Cathode LEDs. Also users can easily configure the LED current from 2.5mA to
20mA by a serial pulse input pin(EN), so the dimming of white LEDs current can be achieved by
applying a pulse signal to the EN pin. The number of falling edges are detected internally and decoded
as illustrated in Table 1.There are totally 8 steps of current value could be set by users. When the EN
pin is held low for 180us or more, the BCT3220 enters the shutdown mode and draw “zero” current
from VIN.
www.broadchip.com
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