MAX6975

www.DataSheet4U.com 19-0555; Rev 0; 5/06 24-Output PWM LED Drivers for Message Boards General Description The MAX6974/MAX6975 precision current-sinking, 24-output PWM LED drivers drive red, green, and blue LEDs for full-color graphic message boards and video displays. Each output has an individual 12-bit (MAX6974) or 14-bit (MAX6975) PWM-intensity (hue) control and 7-bit (MAX6974) or 5-bit (MAX6975) global PWM intensity (luminance) control. The MAX6974/MAX6975 feature a high-speed, fully buffered cascadable serial interface, open-circuit LED fault detection circuitry, as well as a watchdog timer. The driver has three banks of eight outputs, with each bank intended to drive a different color in RGB applications. The full-scale current for each bank of eight outputs is adjustable from 6mA to 30mA in 256 steps (0.3125% per step) to calibrate each color. The MAX6974/MAX6975 can optionally multiplex by using outputs MUX0 and MUX1, which each drive an external pnp transistor. Multiplexing doubles the MAX6974/MAX6975 drive capability to 48 LEDs. The MAX6974/MAX6975 operate from a 3.0V to 3.6V power supply. The LED power supply can range from 3V to 7V. The LED drivers require only 0.8V headroom above the LEDs’ forward-voltage drop. Using a separate LED supply voltage for each LED minimizes power consumption. The serial interface uses differential signaling for the high-speed clock and data signals to reduce EMI and improve signal integrity. The MAX6974/MAX6975 buffer all interface ...