Philips Semiconductors
PCA9552
16-bit I2C-bus LED driver with programmable blink rates
6.4 Pins used as GPIOs
LED pins not used to control LEDs can be used as general purpose I/Os (GPIOs).
For use as input, set LEDn to high-impedance (01) 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. LED 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 PCA9552 in
a reset condition until VDD has reached VPOR. At that point, the reset condition is released
and the PCA9552 registers are initialized to their default states. Thereafter, VDD must be
lowered below 0.2 V to reset the device.
6.6 External RESET
A reset can be accomplished by holding the RESET pin LOW for a minimum of tw(rst). The
PCA9552 registers and I2C-bus state machine will be held in their default states until the
RESET input is once again HIGH.
This input requires a pull-up resistor to VDD if no active connection is used.
PCA9552_5
Product data sheet
Rev. 05 — 9 March 2006
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
9 of 28