PCA9553 Datasheet, PDF(1/26 Page) NXP Semiconductors – 4-bit I2C LED driver with programmable blink rates

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PCA9553 Datasheet, PDF (1/26 Pages) NXP Semiconductors – 4-bit I2C LED driver with programmable blink rates

PCA9553

4-bit I2C-bus LED driver with programmable blink rates

Rev. 06 â 29 December 2008

Product data sheet

1. General description

The PCA9553 LED blinker blinks LEDs in I2C-bus and SMBus applications where it is

necessary to limit bus trafï¬c 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 trafï¬c on the I2C-bus and uses up one of the master's timers. The

PCA9553 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). 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 100 mA per package.

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

Input/Output (GPIO) expansion.

Power-On Reset (POR) initializes the registers to their default state, all zeroes, causing

the bits to be set HIGH (LED off).

Due to pin limitations, the PCA9553 is not featured with hardware address pins. The

PCA9553/01 and the PCA9553/02 have different ï¬xed I2C-bus addresses allowing

operation of both on the same bus.

2. Features

I 4 LED drivers (on, off, ï¬ashing at a programmable rate)

I 2 selectable, fully programmable blink rates (frequency and duty cycle) between

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

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

I Internal oscillator requires no external components

I I2C-bus interface logic compatible with SMBus

I Internal power-on reset

I Noise ï¬lter on SCL/SDA inputs

I 4 open-drain outputs directly drive LEDs to 25 mA

I Controlled edge rates to minimize ground bounce

I No glitch on power-up

I Supports hot insertion

I Low standby current

I Operating power supply voltage range of 2.3 V to 5.5 V

I 0 Hz to 400 kHz clock frequency

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