MAX7219Eight-digit serial LED driver

MAX7219 combines an eight-digit LED driver, display memory and a serial interface in one 24-pin IC. It can control eight common-cathode seven-segment digits or 64 individual LEDs, refreshing the display while the host performs other work. A 16-bit command selects a digit or control register. Code-B decoding handles numbers and a small set of characters; raw segment mode gives direct control of each LED. RSET establishes peak current, while a separate intensity register adjusts PWM brightness. This page uses the industrial-temperature MAX7219ENG+ and MAX7219EWG+ packages with the same pin numbering. The example uses a 5 V host, eight red digits, both ground returns and local bypass capacitors. The MAX7219 clocks data regardless of LOAD, so it must not be treated as a MAX7221 with a clock-gating chip select.