The MAX6972/MAX6973 precision current-sinking, 16-output PWM LED drivers drive red, green, and/or blue LEDs for full-color graphic message boards and video
displays. Each output has an individual 12-bit (MAX6972) or 14-bit (MAX6973) PWM-intensity (hue) control and 7-bit (MAX6972) or 5-bit (MAX6973) global PWM intensity (luminance) control. The MAX6972/MAX6973 also feature open-circuit LED fault-detection circuitry, as well as a watchdog timer.
The driver has two banks of eight outputs, with each bank intended to drive a different color in RGB applications. The standard application uses three MAX6972/MAX6973s to drive eight RGB LEDs. The full-scale current for each bank of eight outputs is adjustable from 11mA to 55mA in 256 steps (0.3125% per step) to calibrate each color.
The MAX6972/MAX6973 can optionally multiplex by using outputs active-low MUX0 and active-low MUX1, which each drive an external pnp transistor. Multiplexing doubles the MAX6972/MAX6973 drive capability to 32 LEDs.
The MAX6972/MAX6973 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 MAX6972/MAX6973 buffer all interface signals to simplify cascading devices in modules that use a large number of drivers.
An internal watchdog timer, when enabled, automatically clears the pixel-data registers and blanks the display if any of the signal inputs fail to toggle within 40ms.
The MAX6972/MAX6973 are available in 32-pin TQFN packages and operate over the -40°C to +125°C temperature range.
Refer to the MAX6974/MAX6975 data sheet for a 24-output, 6mA to 30mA software-compatible device.
Applications
- Graphic Panels
- LED Message Boards
- LED Video Display Panels
- Signs
- Variable Message Signs (VMS)
