PCA9533 datasheet(7/24 Pages) NXP

7 / 24 page

PCA9533_3

Product data sheet

Rev. 03 — 27 April 2009

7 of 24

NXP Semiconductors

PCA9533

4-bit I2C-bus LED dimmer

6.4 Pins used as GPIOs

LEDn pins not used to control LEDs can be used as General Purpose I/Os (GPIOs).

For use as input, set LEDn to high-impedance (00) and then read the pin state via the

INPUT register.

For use as output, connect external pull-up resistor to the pin and size it according to the

DC recommended operating characteristics. LEDn output pin is HIGH when the output is

programmed as high-impedance, and LOW when the output is programmed LOW through

the ‘LED selector’ register. The output can be pulse-width controlled when PWM0 or

PWM1 are used.

6.5 Power-on reset

When power is applied to VDD, an internal Power-On Reset (POR) holds the PCA9533 in

a reset condition until VDD has reached VPOR. At that point, the reset condition is released

and the PCA9533 registers are initialized to their default states, all the outputs in the

OFF state. Thereafter, VDD must be lowered below 0.2 V to reset the device.

PCA9533 データシート(PDF) 7 Page - NXP Semiconductors