A6281: 3-Channel Constant Current LED Driver with Programmable PWM Control

Description

These parts are discontinued. Samples are no longer available. For new customers or new applications, please contact Allegro. Date of status change: December 2, 2014.

The A6281 is a 3-channel constant current LED driver that has a wide range of output currents. The A6281 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 32-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.

The A6281 is designed to minimize the number of components needed to drive LEDs with large pixel spacing. A large number of A6281s can be daisy chained together and controlled by just four control signals (clock, serial data, latch, and output enable). Each of these inputs is buffered to drive the next chip in the chain. Also, VIN can be tied to the LED voltage supply bus, thus eliminating the need for a separate chip supply bus or an external regulator.

The A6281 is supplied in a 3 mm × 3 mm 16-terminal QFN (suffix ‘ES’) package, with 0.75 mm nominal overall height. The package is lead (Pb) free with 100% matte-tin leadframe plating.

Applications

  • Colored, large-character LED signs
  • Scrolling, colored marquees
  • Architectural lighting
  • High intensity monochrome displays
  • Large video and graphic displays

Top Features

  • 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
  • Internally generated PWM clock
  • Serial port operates at up to 5 MHz
  • Data and clock logic architecture allows single microcontroller control of large quantities of serially-connected A6281s at fast data transfer rate
  • Buffered logic outputs to drive cables
  • Thermal shutdown and UVLO protection
  • Power-On Reset

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Compliant
Part Composition /
RoHS Data
Comments Samples Check Stock
A6281EESTR-T 16-lead QFN -40°C to 85°C Yes View Data Discontinued Contact your
local sales rep
Check
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.

Packaging

The A6281 is supplied in a 3 mm × 3 mm 16-terminal QFN (suffix ‘ES’) package, with 0.75 mm nominal overall height. The package is lead (Pb) free with 100% matte-tin leadframe plating.

ES-QFN with exposed pad 16 contact

Design Support Tools