Data Sheet

1997 Apr 02 3
Philips Semiconductors Product specification
Remote 8-bit I/O expander for I
2
C-bus
PCF8574
1 FEATURES
• Operating supply voltage 2.5 to 6 V
• Low standby current consumption of 10 µA maximum
• I
2
C to parallel port expander
• Open-drain interrupt output
• 8-bit remote I/O port for the I
2
C-bus
• Compatible with most microcontrollers
• Latched outputs with high current drive capability for
directly driving LEDs
• Address by 3 hardware address pins for use of up to
8 devices (up to 16 with PCF8574A)
• DIP16, or space-saving SO16 or SSOP20 packages.
2 GENERAL DESCRIPTION
The PCF8574 is a silicon CMOS circuit. It provides general
purpose remote I/O expansion for most microcontroller
families via the two-line bidirectional bus (I
2
C).
The device consists of an 8-bit quasi-bidirectional port and
an I
2
C-bus interface. The PCF8574 has a low current
consumption and includes latched outputs with 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. This means that
the PCF8574 can remain a simple slave device.
The PCF8574 and PCF8574A versions differ only in their
slave address as shown in Fig.9.
3 ORDERING INFORMATION
TYPE NUMBER
PACKAGE
NAME DESCRIPTION VERSION
PCF8574P;
PCF8574AP
DIP16 plastic dual in-line package; 16 leads (300 mil) SOT38-1
PCF8574T;
PCF8574AT
SO16 plastic small outline package; 16 leads; body width 7.5 mm SOT162-1
PCF8574TS SSOP20 plastic shrink small outline package; 20 leads; body width 4.4 mm SOT266-1