MAX6974 Overview
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.
Key Features
- 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
