The Maxim Integrated MAX7219 8-Digit LED Display Driver is a compact, serial input/output common-cathode display driver that interfaces microprocessors to 7-segment numeric LED displays of up to 8 digits, to bar-graph displays, or to 64 individual LEDs. It's an extremely useful chip when you need to control lots of LEDs, such as an LED matrix or a seven-segment display. Each driver can control up to 64 pixels or segments, and you can chain them to control more. They take SPI input to reliably produce a stable display. In addition, this driver natively understands LED matrices and segment displays so you don't have to make your life any harder than it already is by forcing you to map bits to pins.
The device includes an on chip BCD code-B decoder, a multiplex scan circuitry, segment and display drivers, and a 64 Bit (8 x 8) startic RAM memory to store each digit. The memory is used to store the LED settings, so that continuous reprogramming is not necessary. Every individual segment can be addressed and updated separately. Only one external resistor is required to set the current through the LED display. Brightness can be controlled either in an analog or digital way. The user can choose the internal code-B decoder to display numeric digits or to address each segment directly. A convenient 4-wire serial interface connects to all common microprocessors and individual digits may be addressed and updated without rewriting the entire display.
The MAX7219CNG+ features an extremely low shutdown current of only 20µA and an operational current of less than 500µA. The MAX7219CNG+ can be reset by software, an external clock can be used and several test modes support easy debugging. This Maxim Integrated LED display driver includes a 150?A low-power shutdown mode, analog and digital brightness control, a scanlimit register that allows the user to display from 1 to 8 digits, and a test mode that forces all LEDs on.
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