Description
The A6280 is a 3-channel constant current LED driver that
has a wide range of output currents. The A6280 controls LED
brightness with a Pulse Width Modulation (PWM) scheme
that gives the application the capability of displaying a billion
colors in an RGB cluster. The maximum current is set by an
external resistor.
The LED brightness is controlled by performing PWM control
on the outputs. The brightness data of the PWM signal for
each LED is stored in three 10-bit registers. The peak value
for each LED can be adjusted (dot-corrected) to compensate
for mismatch, aging, and temperature effects. All the internal
latched registers are loaded by a 31-bit shift register. One
address bit controls whether dot correction/clock divider ratio
or brightness data is loaded into the registers. The remaining
bits are used for the data. This helps reduce the pin count of
the A6280. To further lower the A6280 pin count, the PWM
clock and the serial bus clock share the same pin and work
concurrently to control LED brightness and to load data.
The A6280 is designed to minimize the number of components
needed to drive LEDs with large pixel spacing. A large number
of A6280s can be daisy chained together and controlled by
just four control signals (clock, serial data, latch, and output
enable). Each of these inputs has buffered outputs to drive
the next chip in the chain. Also, VIN can be tied to the LED
A6280-DS, Rev. 7
3-Channel Constant-Current LED Driver
with Programmable PWM Control
Continued on the next page…
Packages: 16-pin DIP (suffix A), and
16-contact QFN (suffix ES)
Application Diagram
ES, approximate scale 1:1
A6280
Clock
Data
Output Enable
Latch Enable
Microprocessor
Control Board
Clock Out
Data Out
Latch Out
OE Out
Clock In
Data In
Latch In
OE In
V
LED
Out
B
Out
G
Out
R
V
IN
Power Supply Bus
A6280
Pixel Board #1
R
EXT
V
REG
Clock Out
Data Out
OE Out
Clock In
Data In
OE In
V
LED
Out
B
Out
G
Out
R
V
IN
A6280
Pixel Board #2
R
EXT
V
REG
Pixel Board #N
Latch OutLatch In
Cat5 UTP Cat5 UTP Cat5 UTP
Figure 1. Functional drawing of daisy chained display application. Additional pixel boards
with A6280 ICs can be applied.
Features and Benefits
▪ 3 × 10-bit PWM brightness settings
▪ 3 × 7-bit dot correction current settings
▪ 5 to 17 V operation
▪ Wide output current range, 10 to 150 mA per channel
▪ Serial port/PWM clock operates at up to 5 MHz
▪ Data and clock logic architecture allows single
microcontroller control of large quantities of serially-
connected A6280s at fast data transfer rate
▪ Buffered logic outputs to drive cables
▪ Thermal shutdown and UVLO protection
▪ Power-On Reset
