1. General description
The PCA9673 provides general purpose remote I/O expansion for most microcontroller
families via the two-line bidirectional bus (I
2
C-bus) and is a part of the Fast-mode Plus
family.
The PCA9673 is a drop in upgrade for the PCF8575 providing higher Fast-mode Plus
(Fm+) I
2
C-bus speeds (1 MHz versus 400 kHz) so that the output can support PWM
dimming of LEDs, higher I
2
C-bus drive (30 mA versus 3 mA) so that many more devices
can be on the bus without the need for bus buffers, higher total package sink capacity
(400 mA versus 100 mA) that supports having all 25 mA LEDs on at the same time and
more device addresses (16 versus 8) are available to allow many more devices on the
bus without address conflicts.
The difference between the PCA9673 and the PCF8575 is that the A2 address pin is
replaced by a RESET
input on the PCA9673.
The device consists of a 16-bit quasi-bidirectional port and an I
2
C-bus interface. The
PCA9673 has a low current consumption and includes latched outputs with 25 mA high
current drive capability for directly driving LEDs.
It also possesses an interrupt line (INT
) which can be connected to the interrupt logic of
the microcontroller. By sending an interrupt signal on this line, the remote I/O can inform
the microcontroller if there is incoming data on its ports without having to communicate via
the I
2
C-bus.
The internal Power-On Reset (POR), hardware reset pin (RESET
) or software reset
sequence initializes the I/Os as inputs.
2. Features and benefits
1MHz I
2
C-bus interface
Compliant with the I
2
C-bus Fast and Standard modes
SDA with 30 mA sink capability for 4000 pF buses
2.3 V to 5.5 V operation with 5.5 V tolerant I/Os
16-bit remote I/O pins that default to inputs at power-up
Latched outputs with 25 mA sink capability for directly driving LEDs
Total package sink capability of 400 mA
Active LOW open-drain interrupt output
16 programmable slave addresses using 2 address pins
Readable device ID (manufacturer, device type, and revision)
PCA9673
Remote 16-bit I/O expander for Fm+ I
2
C-bus with interrupt and
reset
Rev. 2 — 29 September 2011 Product data sheet
