PCF8574
www.ti.com ............................................................................................................................................................... SCPS068G–JULY 2001–REVISED MAY 2008
REMOTE 8-BIT I/O EXPANDER FOR I2C BUS
1
FEATURES
•
Low Standby-Current Consumption of
10 µA Max
I2C to Parallel-Port Expander
•
•
Compatible With Most Microcontrollers
Latched Outputs With High-Current Drive
Capability for Directly Driving LEDs
•
•
Open-Drain Interrupt Output
•
Latch-Up Performance Exceeds 100 mA Per
JESD 78, Class II
RGY PACKAGE
(TOP VIEW)
DGV OR PW PACKAGE
(TOP VIEW)
RGT PACKAGE
DW OR N PACKAGE
(TOP VIEW)
(TOP VIEW)
1
20
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
INT
SCL
NC
SDA
VCC
A0
P7
P6
19
18
17
16
15
14
13
12
2
3
4
5
6
7
8
9
SCL
NC
SDA
VCC
A0
A1
NC
A2
P6
NC
P5
P4
GND
P3
VCC
SDA
A0
A1
A2
P0
P1
P2
P3
1
2
3
4
5
6
7
8
16
15
NC
P5
P4
GND
P3
14 SCL
VCC
A0
A1
A2
1
2
3
4
12 P6
11 P5
10 P4
INT
P7
P6
P5
P4
13
12
11
10
9
A1
9
GND
NC
P2
NC
A2
P0
NC
P2
P1
GND
10
11
NC – No internal connection
NC – No internal connection
DESCRIPTION/ORDERING INFORMATION
This 8-bit input/output (I/O) expander for the two-line bidirectional bus (I2C) is designed for 2.5-V to 6-V VCC
operation.
The PCF8574 provides general-purpose remote I/O expansion for most microcontroller families via the I2C
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 VCC is
active. An additional strong pullup to VCC 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.
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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.