1. General description
The PCA9500 is an 8-bit I/O expander with an on-board 2-kbit EEPROM.
The I/O expander's eight quasi-bidirectional data pins can be independently assigned as
inputs or outputs to monitor board level status or activate indicator devices such as LEDs.
The system master writes to the I/O configuration bits in the same way as for the
PCF8574. The data for each input or output is kept in the corresponding Input or Output
register. The system master can read all registers.
The EEPROM can be used to store error codes or board manufacturing data for
read-back by application software for diagnostic purposes and is included in the I/O
expander package.
The PCA9500 has three address pins with internal pull-up resistors allowing up to eight
devices to share the common two-wire I
2
C software protocol serial data bus. The fixed
GPIO I
2
C-bus address is the same as the PCF8574 and the fixed EEPROM I
2
C-bus
address is the same as the PCF8582C-2, so the PCA9500 appears as two separate
devices to the bus master.
The PCA9500 supports hot insertion to facilitate usage in removable cards on backplane
systems.
The PCA9501 is an alternative to the functionally similar PCA9500 for systems where a
higher number of devices are required to share the same I
2
C-bus or an interrupt output is
required.
2. Features and benefits
Eight general purpose input/output expander/collector
Drop-in replacement for PCF8574 with integrated 2-kbit EEPROM
Internal 256 8 EEPROM
Self timed write cycle
4 byte page write operation
I
2
C-bus and SMBus interface logic
Internal power-on reset
Noise filter on SCL/SDA inputs
Three address pins allowing up to eight devices on the I
2
C-bus/SMBus
No glitch on power-up
Supports hot insertion
Power-up with all channels configured as inputs
Low standby current
PCA9500
8-bit I
2
C-bus and SMBus I/O port with 2-kbit EEPROM
Rev. 4.1 — 5 May 2017 Product data sheet
