The MAX6979 is a MAXIM-released serial interface LED driver chip with 16 open-drain constant current sinking LED driver outputs rated at 5.5V. The MAX6979 operates from a 3V to 5.5V supply. The MAX6979 supply and the LEDs’ supply can power up in any order. The constant-current outputs are programmed together to up to 55mA using a single external resistor. The MAX6979 operates with a 25Mb, industry-standard, 4-wire serial interface. The MAX6979 includes circuitry that automatically detects open-circuit LEDs.
The MAX6979 serial‑interfaced LED driver provides sixteen open‑drain, constant‑current sinking outputs rated at 5.5 V. It operates from a 3 V to 5.5 V supply and uses a 25 Mb, 4‑wire serial interface to program all outputs together up to 55 mA via a single external resistor.
Key features include automatic open‑circuit LED detection, a watchdog that blanks the display if the serial interface fails, 3 % current matching between outputs, 6 % matching between ICs, and operation over a –40 °C to +125 °C temperature range. The device is offered in 24‑pin TSSOP and PDIP packages.
| Supply voltage range | 3 V to 5.5 V |
|---|---|
| Number of LED outputs | 16 |
| Maximum continuous current per output | 55 mA |
| Current matching between outputs | 3 % |
| Current matching between ICs | 6 % |
| Operating temperature range | -40 °C to +125 °C |
| Serial interface speed | 25 Mb/s |
| Package types | 24‑pin TSSOP, 24‑pin PDIP |
Each output can sink up to 55 mA continuous current.
The LED current is programmed by a single external resistor (RSET).
The watchdog clears all driver output latches, turning off the LEDs until new data is latched.
Open‑circuit LEDs set fault status bits D13 and D14 high, which are shifted out on DOUT with the next data transmission.