Philips Semiconductors
Product specification
Remote 8-bit I/O expander for I
2
C-bus
CONTENTS
1
2
3
4
5
5.1
5.2
6
6.1
6.2
6.3
6.4
7
7.1
7.2
7.3
8
9
10
11
12
13
13.1
13.2
13.2.1
13.2.2
13.3
13.3.1
13.3.2
13.3.3
13.4
14
15
16
17
FEATURES
GENERAL DESCRIPTION
ORDERING INFORMATION
BLOCK DIAGRAM
PINNING
DIP16 and SO16 packages
SSOP20 package
CHARACTERISTICS OF THE I
2
C-BUS
Bit transfer
Start and stop conditions
System configuration
Acknowledge
FUNCTIONAL DESCRIPTION
Addressing
Interrupt output
Quasi-bidirectional I/Os
LIMITING VALUES
HANDLING
DC CHARACTERISTICS
I
2
C-BUS TIMING CHARACTERISTICS
PACKAGE OUTLINES
SOLDERING
Introduction
Through-hole mount packages
Soldering by dipping or by solder wave
Manual soldering
Surface mount packages
Reflow soldering
Wave soldering
Manual soldering
Suitability of IC packages for wave, reflow and
dipping soldering methods
DATA SHEET STATUS
DEFINITIONS
DISCLAIMERS
PURCHASE OF PHILIPS I
2
C COMPONENTS
PCF8574
2002 Nov 22
2
Philips Semiconductors
Product specification
Remote 8-bit I/O expander for I
2
C-bus
1
FEATURES
PCF8574
•
Operating supply voltage 2.5 to 6 V
•
Low standby current consumption of 10
µA
maximum
•
I
2
C-bus 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 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.10.
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-bus).
3
ORDERING INFORMATION
PACKAGE
TYPE NUMBER
NAME
PCF8574P;
PCF8574AP
PCF8574T;
PCF8574AT
PCF8574TS;
PCF8574ATS
DIP16
SO16
SSOP20
DESCRIPTION
plastic dual in-line package; 16 leads (300 mil)
plastic small outline package; 16 leads; body width 7.5 mm
plastic shrink small outline package; 20 leads; body width 4.4 mm
VERSION
SOT38-4
SOT162-1
SOT266-1
2002 Nov 22
3
Philips Semiconductors
Product specification
Remote 8-bit I/O expander for I
2
C-bus
5
5.1
PINNING
DIP16 and SO16 packages
SYMBOL
A0
A1
A2
P0
P1
P2
P3
V
SS
P4
P5
P6
P7
INT
SCL
SDA
V
DD
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
address input 0
address input 1
address input 2
quasi-bidirectional I/O 0
quasi-bidirectional I/O 1
quasi-bidirectional I/O 2
quasi-bidirectional I/O 3
supply ground
quasi-bidirectional I/O 4
quasi-bidirectional I/O 5
quasi-bidirectional I/O 6
quasi-bidirectional I/O 7
interrupt output (active LOW)
serial clock line
serial data line
supply voltage
DESCRIPTION
PCF8574
handbook, halfpage
A0 1
A1 2
A2 3
P0 4
16 VDD
15 SDA
14 SCL
handbook, halfpage
A0 1
A1
2
16 VDD
15 SDA
14 SCL
A2 3
P0
4
PCF8574P
13 INT
P1 5
PCF8574AP
12 P7
11 P6
10 P5
9
MBD979
P1 5
P2 6
P3 7
VSS
8
PCF8574T
13 INT
PCF8574AT
12 P7
11 P6
10 P5
9
MCE001
P2 6
P3 7
VSS
8
P4
P4
Fig.2 Pin configuration (DIP16).
Fig.3 Pin configuration (SO16).
2002 Nov 22
5
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