1.

General description

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

PCA9552 LED blinker instead requires only the initial setup command to program

BLINK RATE 1 and BLINK RATE 2 (that is, 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. Maximum output sink current is 25 mA per bit and 200 mA per package.

Any bits not used for controlling the LEDs can be used for General Purpose Parallel

Input/Output (GPIO) expansion.

The active LOW hardware reset pin (RESET) and Power-On Reset (POR) initializes the

registers to their default state, all zeroes, causing the bits to be set HIGH (LED off).

Three hardware address pins on the PCA9552 allow eight devices to operate on the same

bus.

2.

Features

0.172 Hz and 44 Hz (5.82 seconds and 0.023 seconds)

PCA9552

Rev. 05 — 9 March 2006

Product data sheet