PCA9551BS

8位I2C总线LED驱动器，具有可编程闪烁速率 8-bit I2C-bus LED driver with programmable blink rates

General description

The PCA9551 LED blinker blinks LEDs in I2C-bus and SMBus applications where it is necessary to limit bus traffic or free up the I2C-bus master"s MCU, MPU, DSP, chip set, etc. 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 I2C-bus and uses up one of the master"s 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.

Features

8 LED drivers on, off, flashing at a programmable rate

2 selectable, fully programmable blink rates frequency and duty cycle between 0.148 Hz and 38 Hz 6.74 seconds and 0.026 seconds

Input/outputs not used as LED drivers can be used as regular GPIOs

Internal oscillator requires no external components

I2C-bus interface logic compatible with SMBus

Internal power-on reset

Noise filter on SCL/SDA inputs

Active LOW reset input

8 open-drain outputs directly drive LEDs to 25 mA

Edge rate control on outputs

Maximum output sink current is 25 mA per bit and 100 mA per package.