12-channel LED driver for signage and displays

Diodes has introduced a 12-channel constant-current LED driver arranged as four channels of RGB.

AL58221 has open-drain outputs that can sink up to 60mA and withstand 24V.

Maximum red green and blue currents are set with three resistors, then the individual channels are digitally-modulated to set their brightness.

To reduce flicker, adaptive pulse density modulation is used, with diodes claiming a visual refresh rate of over 1kHz with 16bit greyscale or over 256kHz with 8bits.

Digital control is over a two-wire serial interface, with a 208bit word defining 192bit data plus 16bits of command.

Video signage is one potential application – up to 1,030 devices can be cascaded and the the device supports long connections using clock recovery and pulse re-timing. Data rates between 140kbit/s and 20Mbit/s can be set.

The IC operates over 3 to 5.5V and -40°C to +85°C ambients.

Consumption is typically under 6mA, but to this has to be added ±4.6mA of data drive current.

Packaging is a TSSOP-24, thermally-enhanced to handle up to 4.5W at 25°C ambient with the right heat sinking, and less above 25°C.