16-Port, 36V Constant-Current LED Driver With LED Fault Detection And Watchdog

The MAX6983 serial-interfaced LED Driver provides 16 open-drain, constant-current-sinking LED Driver outputs rated at 36V. The MAX6983 operates from a 3V to 5.5V supply. The MAX6983 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 MAX6983 operates with a 25Mb, industry-standard, 4-wire serial Interface The MAX6983 includes circuitry that automatically detects open-circuit LEDs Fault status is loaded into the serial-interface Shift register when LE goes high and is automatically shifted out on DOUT when the next data transmission is shifted in. The MAX6983 includes a fail-safe feature for safety- related applications, which blanks the Display if the ser- ial Interface fails. If the serial Interface becomes inactive for more than 1s, all driver output Latches are automatically cleared. This turns off all LEDs connected to the outputs. The Shift register data is not disturbed. The outputs remain off until the driver output Latches are updated with data turning them on, so recovery is auto- matic if the transmission failure is temporary. The watchdog function requires no software change to the application driving the MAX6983. The MAX6983 uses the industry-standard shift-register- plus-latch-type serial Interface The driver accepts data shifted into a 16-bit Shift register using data input DIN and Clock input CLK. Input data appears at the output DOUT 16 Clock cycles later to allow cascading of multi- ple MAX6983s. The latch-enable input, LE, loads the 16 bits of shift-register data into a 16-bit output latch to set which LEDs are on and which are off. The output- enable input, OE, Gates all 16 outputs on and off, and is fast enough to be used as a PWM input for LED intensi- ty control. The MAX6983 is one of a family of 12 shift-register-plus- latch-type LED Drivers The family includes 8-port and 16-port types, with 5.5V- or 36V-rated LED outputs, with and without open-circuit LED detection and watchdog. All versions operate from a 3V to 5.5V supply, and are specified over the -40°C to +125°C temperature range. By Maxim Integrated Products