Components: I/O Expanders Dim LEDs In Microprocessor Buses

The PCA9530/31/32/33 2-, 4-, 8-, and 16-bit I/O expanders with a reset function can dim LEDs in I²C and SMBus applications. Each LED may be dimmed in one of 256 brightness levels. Also, they may switch on and off or flash at one of two programmable rates without tying up the bus master or overloading the bus. Blink rates vary between 0.625 and 1.6 seconds. The duty cycle is programmable in 256 steps. LEDs are dimmed by varying the duty cycle, which changes the average current as the LEDs blink at 160 Hz. The ICs contain a ±10% accurate oscillator and need no external parts. Open-drain outputs directly drive LEDs to a maximum of 25 mA/bit. Free samples are available.