May, 2009, REV1.0
BCT3119
9-Channel 64steps Constant-Current LED Driver
with SPI Control
General Description
The BCT3119 is a constant current driver
incorporating shift register and data latch.
This CMOS device is designed for LED
display applications.
The max output constant current can be set
using an external resistor, and 64 steps of
current could be set through a SPI interface
with MCU. Any channel output could have
any step current levels.
Features
♦
9 channel constant-current outputs, up to
40mA each
♦
Each channel current could be controlled
through a SPI interface with MCU
♦
Power-On Reset(POR), all register bits=0
♦
For common-anode LEDs
♦
High data input rate: < 20MHz
♦
2.7V to 5.5V Supply Voltage Range
♦
RoHS Compliant and 100% Lead
Applications
Cell Phones
Multicolor LED lighting
Display backlighting
Toys/Mp3/Mp4/CD/minidiskplayers
(Pb)-Free
Pin Configurations
(Top view)
Ordering Information
PART
BCT3119EGP-TR
PIN-PACKAGE
QFN-20
（3x3mm）
Temp-Range
-40°C to +85°C
Top Mark
3119
www.broadchip.com
May, 2009, REV1.0
9-Channel 64steps Constant-Current LED Driver
Functional Pin Description
Pin
1
2, 3
4
5
6
7 to 15
16 to 19
20
Name
VDD
GND
SPIDATA
SPICK
SPICS
OUT0 to OUT8
NC
REXT
Logic Supply terminal
Logic supply ground and load supply ground
Serial bus data input
Serial bus clock input
Serial bus selection input
Constant current outputs
No connect
Reference current terminal; set maximum output current for all channels
Function
Absolute Maximum Ratings
Characteristic
Symbol
Notes
Rating
Unit
Supply Voltage
VDD
-0.3 to 5.5
V
OUTx Current(any single output)
IO
40
mA
Input Voltage Range
VI
VSPI
-0.3 to VDD+0.3
V
Operating Temperature Range
TA
-40 to 85
℃
Junction Temperature
TJ(max)
150
℃
Storage Temperature Range
Tstg
-55 to 150
℃
Note: “Absolute Maximum Ratings” may cause permanent damage to the device. This is a
stress only rating and operation of the device at these or any other conditions beyond those
indicated in the operational sections of this specification is not implied
Typical Application Circuit
www.broadchip.com
May, 2009, REV1.0
9-Channel 64steps Constant-Current LED Driver
ELECTRICAL CHARACTERISTICS
(VIN = 2.7V to 5.5V, TA =25°C, unless otherwise noted)
PARAMETER
Supply Voltage
Range
Supply Current
Shut Down Current
Output current
accuracy
SYMBOL CONDITIONS
VDD
I
VDD
I
SHUT
operating
REXT=4K, Out0~Out8 NC,
VDD=5.5V
System enter shutdown mode,
VDD=5.5V
REXT=2K，Vdropout=1V
I
O
REXT=4K，Vdropout=1V
REXT=2K，Vdropout =1V
，
I
O
=40mA
MIN
2.7
TYP MAX
5.5
1.6
2
2
UNITS
V
mA
uA
35
18
40
20
±1
±1
400
300
45
mA
22
±3
%
±3
500
500
V
0.3
VDD
V
mV
Output current match
REXT=4K，Vdropout =1V
，I
O
=20mA
Dropout voltage
Logic Input-Logic
High
Logic Input-Logic
Low
Vdrop
V
IH
V
IL
VDD=3.3V
，
I
O
=40mA
VDD=3.3V
，
I
O
=20mA
0.6
VDD
Serial Port Interface (SPI)
This module is used to receive the commands transmitted by Micro Controller. It will decode the
received data and send corresponding commands to signal processing and analog blocks. The 16-bit
serial interface uses three pins –“SPICS/SPIDATA / SPICK” to enter data. Data read is not available
with the serial interface and data entered must be 16 bits.
The description of three pins is:
Signal Name
SPICK
SPIDATA
SPICS
Attribute
Edge Triggered
Level
Active Low
Direction
MCU->BCT3119
MCU->BCT3119
MCU->BCT3119
Description
Serial bus clock
Serial data
SPI bus selection
www.broadchip.com
May, 2009, REV1.0
9-Channel 64steps Constant-Current LED Driver
Figure 2 shows the timing diagram of this serial interface. When the block is idle, SPICK is forced LOW
and SPICS is forced HIGH. Once the data register contains data and the interface is enabled, SPICS is
pulled LOW and remains LOW for the duration of the transmission.
Figure 2. SPI Interface Transfer Diagram(normal operation)
Figure 3. SPI Interface Timing Diagram
Serial Port Interface Timing
Symbol
Ts
Th
Parameter
SPIDATA to SPICK setup time
SPIDATA to SPICK hold time
Min
4
20
Tye
Max
Unit
ns
ns
Register Definitions
Output Channel Control Register
A7
0
0
0
0
0
0
0
0
0
A6
0
0
0
0
0
0
0
0
0
A5
0
0
0
0
0
0
0
0
0
A4
0
0
0
0
0
0
0
0
0
A3
0
0
0
0
0
0
0
0
1
A2
0
0
0
0
1
1
1
1
0
A1
0
0
1
1
0
0
1
1
0
A0
0
1
0
1
0
1
0
1
0
Output Channel
Out0
Out1
Out2
Out3
Out4
Out5
Out6
Out7
Out8
www.broadchip.com
May, 2009, REV1.0
9-Channel 64steps Constant-Current LED Driver
DIMMING Control Register
D7
0
0
0
0
0
0
0
0
…
0
0
0
0
0
0
0
D6
0
0
0
0
0
0
0
0
…
0
0
0
0
0
0
0
D5
0
0
0
0
0
0
0
0
…
1
1
1
1
1
1
1
D4
0
0
0
0
0
0
0
0
…
1
1
1
1
1
1
1
D3
0
0
0
0
0
0
0
0
…
1
1
1
1
1
1
1
D2
0
0
0
0
1
1
1
1
…
0
0
0
1
1
1
1
D1
0
0
1
1
0
0
1
1
…
0
1
1
0
0
1
1
D0
0
1
0
1
0
1
0
1
…
1
0
1
0
1
0
1
Status
off
2/64 max
3/64 max
4/64 max
5/64 max
6/64 max
7/64 max
8/64 max
….
58/64 max
59/64 max
60/64 max
61/64 max
62/64 max
63/64 max
64/64 max
Note:
“n/64 max” means
Output Current= (max current value
× n) ÷ 64
SHUTDOWN MODE CONTROL REGISTER
A7
1
D7
0
A6
1
D6
0
A5
1
D5
0
A4
1
D4
0
A3
1
D3
0
A2
1
D2
0
A1
1
D1
0
A0
1
D0
0
System enter
shutdown mode
Maximum output current setting
The maximum output current per channel is set by a single external resistor, REXT, which is
placed between the REXT pin and GND pin. The maximum channel output current can be calculated
as:
Io(max)= 0.4*200/REXT.
The max output current REXT values
REXT(K
Ω)
IOmax(mA)
2
3
4
5
40
27
20
16
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