PCF8574 Datasheet PDF - NXP

Part Number PCF8574
Description Remote 8-bit I/O expander for I2C-bus
Manufacturers NXP 
Logo NXP Logo 

Preview ( 30 pages )
PCF8574 datasheet, circuit
PCF8574; PCF8574A
Remote 8-bit I/O expander for I2C-bus with interrupt
Rev. 5 — 27 May 2013
Product data sheet
1. General description
The PCF8574/74A provides general-purpose remote I/O expansion via the two-wire
bidirectional I2C-bus (serial clock (SCL), serial data (SDA)).
The devices consist of eight quasi-bidirectional ports, 100 kHz I2C-bus interface, three
hardware address inputs and interrupt output operating between 2.5 V and 6 V. The
quasi-bidirectional port can be independently assigned as an input to monitor interrupt
status or keypads, or as an output to activate indicator devices such as LEDs. System
master can read from the input port or write to the output port through a single register.
The low current consumption of 2.5 A (typical, static) is great for mobile applications and
the latched output ports directly drive LEDs.
The PCF8574 and PCF8574A are identical, except for the different fixed portion of the
slave address. The three hardware address pins allow eight of each device to be on the
same I2C-bus, so there can be up to 16 of these I/O expanders PCF8574/74A together on
the same I2C-bus, supporting up to 128 I/Os (for example, 128 LEDs).
The active LOW open-drain interrupt output (INT) can be connected to the interrupt logic
of the microcontroller and is activated when any input state differs from its corresponding
input port register state. It is used to indicate to the microcontroller that an input state has
changed and the device needs to be interrogated without the microcontroller continuously
polling the input register via the I2C-bus.
The internal Power-On Reset (POR) initializes the I/Os as inputs with a weak internal
pull-up 100 A current source.
2. Features and benefits
I2C-bus to parallel port expander
100 kHz I2C-bus interface (Standard-mode I2C-bus)
Operating supply voltage 2.5 V to 6 V with non-overvoltage tolerant I/O held to VDD
with 100 A current source
8-bit remote I/O pins that default to inputs at power-up
Latched outputs directly drive LEDs
Total package sink capability of 80 mA
Active LOW open-drain interrupt output
Eight programmable slave addresses using three address pins
Low standby current (2.5 A typical)
40 C to +85 C operation
ESD protection exceeds 2000 V HBM per JESD22-A114 and 1000 V CDM per

No Preview Available !

1 page
PCF8574 equivalent
NXP Semiconductors
PCF8574; PCF8574A
Remote 8-bit I/O expander for I2C-bus with interrupt
7. Functional description
Refer to Figure 1 “Block diagram”.
7.1 Device address
Following a START condition, the bus master must send the address of the slave it is
accessing and the operation it wants to perform (read or write). The address format of the
PCF8574/74A is shown in Figure 6. Slave address pins A2, A1 and A0 are held HIGH or
LOW to choose one of eight slave addresses. To conserve power, no internal pull-up
resistors are incorporated on A2, A1 or A0, so they must be externally held HIGH or LOW.
The address pins (A2, A1, A0) can connect to VDD or VSS directly or through resistors.
slave address
slave address
0 1 0 0 A2 A1 A0 0
0 1 1 1 A2 A1 A0 0
a. PCF8574
b. PCF8574A
Fig 6. PCF8574 and PCF8574A slave addresses
The last bit of the first byte defines the operation to be performed. When set to logic 1 a
read is selected, while a logic 0 selects a write operation (write operation is shown in
Figure 6).
7.1.1 Address maps
The PCF8574 and PCF8574A are functionally the same, but have a different fixed portion
(A6 to A3) of the slave address. This allows eight of the PCF8574 and eight of the
PCF8574A to be on the same I2C-bus without address conflict.
Table 4. PCF8574 address map
Pin connectivity
Address of PCF8574
Address byte value
A2 A1 A0 A6 A5 A4 A3 A2 A1 A0 R/W Write
Read hexadecimal
without R/W
VSS VSS VSS 0 1 0 0 0 0 0 -
VSS VSS VDD 0 1 0 0 0 0 1 -
VSS VDD VSS 0 1 0 0 0 1 0 -
VSS VDD VDD 0 1 0 0 0 1 1 -
VDD VSS VSS 0 1 0 0 1 0 0 -
VDD VSS VDD 0 1 0 0 1 0 1 -
VDD VDD VSS 0 1 0 0 1 1 0 -
VDD VDD VDD 0 1 0 0 1 1 1 -
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 5 — 27 May 2013
© NXP B.V. 2013. All rights reserved.
5 of 33

5 Page

Information Total 30 Pages
Download[ PCF8574.PDF Datasheet ]

Share Link :

Electronic Components Distributor

SparkFun Electronics Allied Electronics DigiKey Electronics Arrow Electronics
Mouser Electronics Adafruit Element14 Chip One Stop

Featured Datasheets

Part NumberDescriptionManufacturers
PCF8570The function is 256 x 8-bit static low-voltage RAM with I2C-bus interface.NXP
PCF8570CThe function is 128 x 8 Bit / 256 x 8 Bit Static Ram with IC Bus Interface.Philips
PCF8570PThe function is 256 x 8-bit static low-voltage RAM with I2C-bus interface.NXP

Quick jump to:

PCF8  1N4  2N2  2SA  2SC  74H  ADC  BC  BF  BU  CXA  HCF  IRF  KA  KIA  LA  LM  MC  NE  ST  STK  TDA  TL  UA is an Online Datasheet PDF Search Site.
It offers a large amount of data sheet, You can free PDF files download.
The updated every day, always provide the best quality and speed.

keyword : PCF8574 schematic, equivalent, pinout, replacement, circuit, manual   |  2020   |  Privacy Policy |  Contact Us  | New  |  Search