1
FEATURES
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
A0
A1
A2
P0
P1
P2
P3
GND
V
CC
SDA
SCL
INT
P7
P6
P5
P4
DW OR N PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
INT
SCL
NC
SDA
V
CC
A0
A1
NC
A2
P0
P7
P6
NC
P5
P4
GND
P3
NC
P2
P1
DGV OR PW PACKAGE
(TOP VIEW)
NC – No internal connection
RGY PACKAGE
(TOP VIEW)
1 20
10 11
2
3
4
5
6
7
8
9
19
18
17
16
15
14
13
12
P6
NC
P5
P4
GND
P3
NC
P2
SCL
NC
SDA
V
CC
A0
A1
NC
A2
INT
P1
P7
P0
NC – No internal connection
RGT PACKAGE
(TOP VIEW)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
P7
INT
SCL
SDA
P0
P1
P2
P3
GND
P4
P5
P6V
CC
A0
A1
A2
DESCRIPTION/ORDERING INFORMATION
PCF8574
www.ti.com
............................................................................................................................................................... SCPS068G – JULY 2001 – REVISED MAY 2008
REMOTE 8-BIT I/O EXPANDER FOR I
2
C BUS
• Low Standby-Current Consumption of • Compatible With Most Microcontrollers
10 µ A Max
• Latched Outputs With High-Current Drive
• I
2
C to Parallel-Port Expander Capability for Directly Driving LEDs
• Open-Drain Interrupt Output • Latch-Up Performance Exceeds 100 mA Per
JESD 78, Class II
This 8-bit input/output (I/O) expander for the two-line bidirectional bus (I
2
C) is designed for 2.5-V to 6-V V
CC
operation.
The PCF8574 provides general-purpose remote I/O expansion for most microcontroller families via the I
2
C
interface [serial clock (SCL), serial data (SDA)].
The device features an 8-bit quasi-bidirectional I/O port (P0 – P7), including latched outputs with high-current drive
capability for directly driving LEDs. Each quasi-bidirectional I/O can be used as an input or output without the use
of a data-direction control signal. At power on, the I/Os are high. In this mode, only a current source to V
CC
is
active. An additional strong pullup to V
CC
allows fast rising edges into heavily loaded outputs. This device turns
on when an output is written high and is switched off by the negative edge of SCL. The I/Os should be high
before being used as inputs.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Copyright © 2001 – 2008, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
