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PCF8574 Expander: Datasheet, Pinout, Circuit

  • Contents

The PCF8574 is an I2C bus to 8-bot parallel bus IO expander IC. It provides GPIO  expansion for many microcontrollers in a simple and cost-effective method. The interface for this IC is I2C  (or I2C) using SDA  (Data) and SCL  (Clock) lines. So, if your microcontroller has a limited number of IO pins and has I2C capability, then you can use this IC to expand the IO pins.

Here is a video of PCF8574 I2C GPIO Expander Tutorial

Catalog

PCF8574 Pinout

PCF8574 Circuit

PCF8574 Application

PCF8574 Feature

PCF8574 Advantage

PCF8574 Package

PCF8574 Parameters

PCF8574 Manufacturer

PCF8574 Documents

PCF8574 Functional Block Diagram

Component Datasheet

FAQ


PCF8574 Pinout

PCF8574 Pinout

PIN

TYPE

DESCRIPTION

NAME

RGT

RGY

DGV or PW

DW or N

A [0..2]

2, 3, 4

6, 7, 9

6, 7, 9

1, 2, 3

I

Address inputs 0 through 2. Connect directly to VCC or ground. Pullup resistors are not needed.

GND

9

15

15

8

Ground

INT

14

1

1

13

O

Interrupt output. Connect to VCC through a pullup resistor.

NC

-

3, 8, 13, 18

3, 8, 13, 18

-

Do not connect

P[0..7]

5, 6, 7, 8, 10, 11, 12, 13

10, 11, 12, 14, 16, 17, 19, 20

10, 11, 12, 14, 16, 17, 19, 20

4, 5, 6, 7, 9, 10, 11, 12

I/O

P-port input/output. Push-pull design structure.

SCL

15

2

2

14

I

Serial clock line. Connect to VCC through a pullup resistor

SDA

16

4

4

15

I/O

Serial data line. Connect to VCC through a pullup resistor.

VCC

1

5

5

16

Voltage supply


PCF8574 Circuit

PCF8574 four-key four-LED control circuit

PCF8574 four-key four-LED control circuit


PCF8574 Application

1. Telecom Shelters: Filter Units

2. Servers

3. Routers (Telecom Switching Equipment)

4. Personal Computers

5. Personal Electronics

6. Industrial Automation

7. Products with GPIO -Limited Processors


PCF8574 Feature

1. Low Standby-Current Consumption of 10 μA Max

2. I2C to Parallel-Port Expander

3. Open-Drain Interrupt Output

4. Compatible with Most Microcontrollers

5. Latched Outputs with High-Current Drive Capability for Directly Driving LEDs

6. Latch-Up Performance Exceeds 100 mA Per JESD 78, Class II


PCF8574 Advantage

PCF8574

PCF8574 8-bit input/output (I/O) expander

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 device provides general-purpose remote I/O expansion for most microcontroller families by way of 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.


PCF8574 Package

PART NUMBER

PACKAGE (PIN)

BODY SIZE (NOM)

PCF8574

TVSOP (20)

5.00 mm × 4.40 mm

SOIC (16)

10.30 mm × 7.50 mm

PDIP (16)

19.30 mm × 6.35 mm

TSSOP (20)

6.50 mm × 4.40 mm

QFN (16)

3.00 mm × 3.00 mm

VQFN (20)

4.50 mm × 3.50 mm


PCF8574 Parameters

Number of I/Os

8

Features

Interrupt pin

Supply voltage (Min) (V)

2.5

Supply voltage (Max) (V)

6

Addresses

8

Rating

Catalog

Frequency (Max) (kHz)

100

Operating temperature range (C)

-40 to 85


PCF8574 Manufacturer

TI Logo

Texas Instruments Inc. (TI)  is an American technology company that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globally. Its headquarters are in Dallas, Texas, United States. TI is one of the top ten semiconductor companies worldwide, based on sales volume. Texas Instruments's focus is on developing analog chips and embedded processors, which accounts for more than 80% of their revenue. TI also produces TI digital light processing (DLP) technology and education technology products including calculators, microcontrollers and multi-core processors. To date, TI has more than 43,000 patents worldwide.


PCF8574 Documents

PCF8574 and PCF8574A Application Clip

Aug. 18, 2004

Improving System Interrupt Management Using the PCF8574 and PCF8574A I/O Expande   

Jul. 27, 2001


PCF8574 Functional Block Diagram

PCF8574 Simplified Block Diagram of Device

 

Simplified Block Diagram of Device

 

PCF8574 Simplified Schematic Diagram of Each P-Port Input/Output

Simplified Schematic Diagram of Each P-Port Input/Output


Component Datasheet

PCF8574 Datasheet


FAQ

  • What is the interface for the PCF8574?

SDA (Data) and SCL (Clock) lines

  • What does the PCF8574 feature?

8-bit quasi-bidirectional I/O port

  • What type of expander is designed for the two-line bidirectional bus?

8-bit input/output (I/O) expander

  • What is PCF8574A?

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 (I2C). The device consists of an 8-bit quasi-bidirectional port and an I2C-bus interface.

  • What is I2C IO Expander?

The I/O expander adds additional GPIO ports. These can be used as both inputs, and outputs at either 3.3V or 5V. ... I2C is a two wire bus, the connections are called SDA (Serial Data) and SCL (Serial Clock).

 

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