A6280 Datasheet, PDF (1/11 Pages) Allegro MicroSystems – 3 Bit Constant Current LED Driver with PWM Control

A6280
3 Bit Constant Current LED Driver with PWM Control
Features and Benefits
▪ 5 to 17 V operation
▪ Wide output current range (10 to 150 mA per output)
▪ 3 × 7 bit Dot Correction current settings
▪ 31 bit shift register
▪ 3 ×10 bit PWM luminance settings
▪ Buffered output control pins
▪ Up to 5 MHz serial / PWM clock frequency
▪ Thermal Shutdown / UVLO
Packages: 16 pin DIP (suffix A), and
16 pin QFN/MLP (suffix ES)
ES, approximate scale 1:1
Description
The A6280 is a 3 bit constant current LED driver that has a wide
range of output currents. The A6280 controls LED luminance
with a pulse width modulation (PWM) scheme that gives the
application the capability of displaying a billion colors. The
overall maximum current is set by an external resistor.
The LED luminance is controlled by performing PWM control
on the outputs. The luminance data of the PWM signal for each
LED is stored in three 10 bit registers. Each LED can be dot
corrected by a 7 bit scalar register that scales the maximum
current from 100% down to 36.5%. All the internal latched
registers are loaded by a 31 bit serial shift register. One bit is used
to control the type of data loaded into the registers, either dot
correction / clock divider ratio or luminance data. The remaining
30 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 luminance and to load data.
The A6280 is designed to minimize the number of components
needed to drive LEDs with large pixel spacing. Several 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 on chip. Also, the VIN pin
Continued on the next page…
Application Diagram
Power Supply Bus
Clock
Data
Strobe
Output Enable
Microprocessor
Control Board
Cat5 UTP
VLED
VIN OutR OutG OutB
Clock In
Clock Out
Data In
Data Out
Strobe In Strobe Out
OE In
OE Out
V_REG A6280 ^REXT
Pixel Board #1
Cat5 UTP
VLED
VIN OutR OutG OutB
Clock In
Clock Out
Data In
Data Out
Strobe In Strobe Out
OE In
OE Out
V_REG A6280 ^REXT
Pixel Board #2
Cat5 UTP
Pixel Board #N
Figure 1. Functional drawing of daisy chained display application. Additional pixel boards
with A6280 ICs can be applied.
A6280-DS, Rev. 1