PCA9551D,118

The PCA9551D,118 is a 8-bit I?C-bus LED Driver with programmable blink rates. The LED blinker blinks LEDs in I?C-bus and SMBus applications where it is necessary to limit bus traffic or free up the I?C-bus masters (MCU, MPU, DSP, chip set) timer. The uniqueness of this device is the internal oscillator with two programmable blink rates. To blink LEDs using normal I/O expanders like the PCF8574 or PCA9554, the bus master must send repeated commands to turn the LED on and off. This greatly increases the amount of traffic on the I?C-bus and uses up one of the masters timers. The PCA9551 LED blinker instead requires only the initial set-up command to program blink rate 1 and blink rate 2 (i.e., the frequency and duty cycle) for each individual output. From then on, only one command from the bus master is required to turn each individual open-drain output on, off or to cycle at blink rate 1 or blink rate 2.