
PCA9532_4 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 04 — 17 March 2009 9 of 29
NXP Semiconductors
PCA9532
16-bit I
2
C-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
INPUT0 or INPUT1 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 V
DD
, an internal Power-On Reset (POR) holds the PCA9532 in
a reset condition until V
DD
has reached V
POR
. At that point, the reset condition is released
and the PCA9532 registers are initialized to their default states, all the outputs in the
OFF state. Thereafter, V
DD
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 t
w(rst)
. The
PCA9532 registers and I
2
C-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 V
DD
if no active connection is used.
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