Product category:
Power Supply ICs and Controllers
News Release from: Allegro MicroSystems Europe | Subject: A6280
Edited by the Electronicstalk Editorial
Team on 09 March 2007
Driver cuts LED display component count
A 3bit constant-current LED driver enables users to minimise the number of components needed to drive LEDs with large pixel spacing.
The A6280 from Allegro MicroSystems Europe is a 3bit constant current LED driver that enables users to minimise the number of components needed to drive LEDs with large pixel spacing The new driver controls LED luminance using a pulsewidth modulation (PWM) scheme which gives the application the capability of displaying up to one billion colours
This article was originally published on Electronicstalk on 30 Aug 2000 at 8.00am (UK)
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An external resistor is used to set the overall maximum current, which can be set over a wide range from 10 to 150mA per output.
An integrated linear regulator allows operation at voltages from 5 to 17V.
Several A6280 devices can be daisychained together and controlled by four control signals (clock, serial data, latch and output enable).
Each of these inputs has buffered outputs on the chip.
The input voltage pin can be tied to the LED voltage supply bus, thus eliminating the need for a separate chip supply bus or an external linear regulator.
Performing PWM control on the outputs controls the LED luminance.
The luminance data of the PWM signal for each LED is stored in three 10bit registers.
Each LED can be dot-corrected by a 7bit scalar register which scales the maximum current from 100% down to 36.5%.
A 31bit serial shift register loads all the internal latched registers.
One bit is used to control whether dot correction/clock divider ratio or luminance data is loaded into the registers.
The remaining 30bit is used for the data.
This helps to reduce the pin count of the A6280.
To further lower the 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 supplied in a 16-lead dual-inline package (suffix A) or a 16-lead MLP package (suffix ES).
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