Allegro® recently announced the release of two new LED driver ICs for use in displays, signs, and control panels. The A6282 and A6285 both have 16 constant‐current output channels. They have serial data inputs and outputs, which can be cascaded to create large, megapixel text or video displays. They can also be used in smaller applications such as LCD backlighting or controlling LEDs in an instrument or control panel.

The brightness of all channels may be adjusted simultaneously by pulse width modulating (PWM) the output enable (OE) input. The serial interface can be coupled directly to microprocessor or FPGA-based systems with speed up to 30 MHz, while a serial data output permits cascading of multiple devices in applications requiring more than 16 channels. Open LED connections can be detected and reported to the host controller through the same serial data output. The FAULT output flags an LED open circuit condition or an over temperature (thermal shutdown) condition. The Open LED detection allows remote diagnosis of failed LEDs. 

Both the A6282 and A6285 operate with LED supply voltages up to 12V, which allows stacking of three or more LEDs per channel. Logic supply voltage can range from 3.3V to 5V, in many cases allowing the device to be powered from the same supply as the LEDs it is driving. The maximum LED drive current can be set by a single external resistor. Both devices feature an undervoltage lockout (UVLO) protection and power-on reset (POR). Staggered delays on the drive outputs during ON/OFF transitions help to reduce noise on the ground line and minimize radiated EMI.

The A6282 is a basic 16-channel driver. Each output can drive up to 50mA. Its excellent channel-to-channel output current matching of ±3% ensures high quality displays and is improved over several alternate sources. It includes an input shift register, accompanying data latches, and 16 constant-current sink drivers. The CMOS shift registers and latches allow direct interfacing with microprocessor-based systems and supply voltages of 3.3 to 5V.

The A6285 has additional features that enable it to be used in video applications. Each of the 16 channels can sink a constant current up to 80 mA. Each channel’s drive current can be individually adjusted from 0 to 100% of the maximum value via a 7-bit Dot Correction register. Dot correction allows the user to adjust each channel’s output current to compensate for initial device mismatch and LED gain. The drive outputs have active pull-ups for high-speed refresh of video and graphic displays, eliminating ghosting and improving picture quality for moving images.

The A6282 is available in 24-lead surface-mount packages: QFN, SOIC, and TSSOP. The A6285 comes in a 32-lead QFN. Samples of both devices in all packages are available now.