Allegro Offers Eight Channel BiCMOS LED Driver
Allegro Microsystems Inc. now offers the A6278, a new eight channel, constant-current latched LED driver with open LED detection, specifically designed for LED-display applications. Each BiCMOS device includes an 8-bit CMOS shift register, accompanying data latches, and 8 npn constant-current sink drivers.
The new device is available in several package options and allowable package power dissipation. This device provides the user with an open LED feature that allows the user to quickly identify system problems. In addition, the A6278 offers an output delay feature that improves ground current spikes. This new device is targeted at the industrial, medical and telecommunications markets.
The CMOS shift register and latches allow direct interfacing with microprocessor-based systems. With a 3.3V or 5V logic supply, typical serial data-input rates are up to 25 MHz. The LED drive current is determined by the user's selection of a single resistor. A CMOS serial output permits cascade connections in applications requiring additional drivelines. Opened LED connections can be detected and fed back to the host microprocessor through the serial data out pin.
The three package styles are provided for through-hole DIP (suffix A), surface-mount SOIC (suffix LW) and exposed pad TSSOP (suffix LP) applications. Under normal applications, a copper lead frame and low logic-power dissipation allow the dual in-line package to sink maximum rated current through all outputs continuously over the operating temperature range (90 mA, 0.75 V drop, +85°C). The A6278 is available in a lead (Pb) free version (suffix -T), with 100% matte tin plated lead-frames.
