PCF8574N - 8-Bit 100kHz I2C I/O Expander | Texas Instruments
MPN: PCF8574N ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
PCF8574N Overview
What is an I2C I/O expander? An I/O expander is an interface IC that translates serial bus commands into parallel digital signals. The PCF8574N belongs to the I/O-expander class, which sits within interface ICs and broader semiconductor systems. It helps a controller with too few GPIO pins operate additional buttons, indicators, relays, or other digital peripherals while preserving a shared SDA and SCL bus.
Key features include eight I/O ports, 100kHz I2C operation, a 2.5V to 6V supply range, and an interrupt output. Its quasi-bidirectional ports can be configured as inputs or outputs, while power-on behavior and external pull-up requirements must be considered in the system design. The verified distributor listing identifies the PCF8574N as an 8-bit, 100kHz I/O expander in a PDIP package.
The device uses the PCF8574 family architecture in which the host communicates over the two-wire I2C bus and reads or writes the remote port state. Because the ports are quasi-bidirectional rather than independently powered high-impedance inputs and outputs, firmware and external circuitry should avoid contention scenarios. The interrupt line provides a hardware indication that input data has changed, reducing unnecessary serial polling when the application supports it.
Typical applications include microcontroller GPIO expansion, keypad and control panels, relay or indicator interfaces, industrial automation modules, communications equipment, and embedded systems using the site-listed STM32, ATMEGA, MSP430, or other microcontroller families. The same I2C bus can support multiple addressed peripherals, subject to the device address configuration and bus capacitance requirements.
Designers should follow the manufacturer datasheet for pull-up resistor selection, address strapping, decoupling, input/output polarity, and interrupt handling. Confirm the available voltage range against the connected bus and peripherals, and verify absolute maximum ratings before using the device in systems with long cables or exposed connectors. The 16-pin PDIP package favors through-hole prototyping rather than compact surface-mount production.
This page combines the verified manufacturer and distributor information for PCF8574N with package, selection, design, and application guidance. It is intended to help engineers identify whether the part fits a particular I2C expansion requirement before comparing alternatives or requesting supply.
Drop-in alternatives for PCF8574N — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PCF8574AN
✅ Drop-In📋 Reference alternative (not in catalog)
PCF8574APW
✅ Drop-In📋 Reference alternative (not in catalog)
PCF8574AP
✅ Drop-In📋 Reference alternative (not in catalog)
PCF8574NE4
✅ Drop-In📋 Reference alternative (not in catalog)
TCA9548ARGER
✅ Drop-In📋 Reference alternative (not in catalog)
PCF8574N Specifications
| Product Type | 8-bit I2C I/O expander |
| Supply Voltage Range | 2.5V to 6V |
| I2C Bus Frequency | 100kHz |
| Number of I/O Ports | 8 |
| Interface | I2C two-line bidirectional bus |
| Interrupt Function | Interrupt output |
| Package | 16-pin PDIP |
| Mounting Type | Through-hole |
| Operating Voltage | 2.5V to 6V VCC operation |
| Device Description | Remote 8-bit input/output expander |
| Port Configuration | Quasi-bidirectional I/O |
| Pin Count | 16 pins |
PCF8574N 16-pin pdip Pin Configuration Guide
Pin configuration for PCF8574N (16-pin pdip package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for PCF8574N.
Refer to the datasheet for full pin configuration.
Typical Applications
PCF8574N is suitable for 6 applications: Microcontroller GPIO Expansion, Embedded Keypad and Control Panel, Relay and Indicator Interface, Industrial Automation Module, Communications Equipment Control, IoT Sensor Hub.
Microcontroller GPIO Expansion
The PCF8574N adds eight remote digital lines to a microcontroller through its verified 100kHz I2C interface, reducing the need to select a larger host package when the application has additional buttons, indicators, or control signals. Place the expander between the host and external circuitry, configure address straps, and use suitable SDA and SCL pull-ups. Its quasi-bidirectional ports require firmware to avoid contention, so initialize outputs carefully and validate each attached circuit against the datasheet.
Recommended
Embedded Keypad and Control Panel
The PCF8574N can scan a compact keypad or expose panel-control signals through eight I/O ports while sharing the host I2C bus. The verified 2.5V to 6V supply range supports integration with low-voltage embedded systems, but the input and output modes must be managed according to the quasi-bidirectional architecture. Address selection, debounce behavior, pull-up requirements, and interrupt use should be tested together because mechanical contacts and external circuitry can affect the final host-firmware design.
Recommended
Relay and Indicator Interface
The PCF8574N can provide a compact serial-to-parallel control path for indicators and suitable external control loads when the selected external devices stay within the applicable electrical limits. Its eight ports provide more parallel control points than many small microcontroller packages, while the 100kHz I2C link keeps wiring compact. Because the PCF8574N ports are quasi-bidirectional and are not intended as unrestricted high-current drivers, use appropriate transistor or driver stages for relays and larger loads, and verify all pull-up and supply arrangements.
Recommended
Industrial Automation Module
The PCF8574N is useful when an industrial or building-automation controller needs additional digital status and command lines without expanding its main GPIO count. The verified I2C interface and interrupt feature allow remote I/O to share wiring with other addressed peripherals, while the 2.5V to 6V range helps align with embedded control rails. Production designs should verify isolation, surge, grounding, cable-length, and environmental requirements separately because the supplied data does not establish industrial or automotive qualification.
Recommended
Communications Equipment Control
The PCF8574N can extend a communications controller with local control and status signals for indicators, resets, enables, or configuration inputs. Using the same SDA and SCL bus for addressable peripherals reduces wiring compared with dedicating separate host pins. The verified 100kHz bus rate and eight-port capacity make the device appropriate for modest control tasks, while the 16-pin PDIP package simplifies through-hole prototypes. Firmware must account for the device address and for the distinction between input monitoring and output-driving behavior.
Recommended
IoT Sensor Hub
The PCF8574N can add discrete sensor-enable, reset, or status lines to an IoT sensor hub built around a microcontroller. Its eight ports provide a practical expansion interface for devices that do not themselves require high-speed serial data. The 2.5V to 6V operating range and 100kHz I2C operation align with many embedded platforms, but sensor leakage, pull-up loading, and power sequencing should be checked. The interrupt output may help the host respond to external input changes, subject to the datasheet timing and polarity requirements.
Recommended
Recommended Products Summary
Engineering reference data for PCF8574N — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PCF8574AN | PCF8574APW | PCF8574AP | PCF8574NE4 | TCA9548ARGER |
|---|---|---|---|---|---|---|
| Product Type | 8-bit I2C I/O expander | PCF8574-family I/O expander | PCF8574-family I/O expander | PCF8574-family I/O expander | PCF8574-family I/O expander | I2C switch/multiplexer |
| Number of I/O Ports | 8 | 8 | 8 | 8 | 8 | Not applicable; I2C switch |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
Key Differentiators
- Eight-port parallel expansion with a simple I2C interface (vs TCA9548ARGER)
- 100kHz verified bus operation for standard embedded control (vs PCF8574AN)
- Through-hole PDIP-16 package for prototyping (vs TCA9548ARGER)
Design Notes
Use the verified 2.5V to 6V operating range as the design boundary, but confirm the exact PCF8574N electrical limits in the manufacturer datasheet. Place the device's supply decoupling close to VCC and ground pins, and account for the voltage drop and current required by attached external circuitry. Because the I/O architecture is quasi-bidirectional, avoid circuits that force an output high while firmware or another device drives it low.
Route SDA and SCL as a compact I2C bus and place pull-up resistors at locations calculated for the bus voltage, capacitance, sink current, and number of devices. Keep the address-strap and interrupt connections accessible for configuration and testing. The PCF8574N is verified as a PDIP-16 part, so provide adequate through-hole spacing, pin-1 orientation, and soldering clearance in the PCB footprint.
Do not treat the eight ports as ordinary independently buffered GPIOs. Configure their intended input or output state before enabling external loads, prevent simultaneous opposing drive paths, and account for the power-on state in firmware. The verified 100kHz interface is a design constraint; do not assume higher-speed operation without a separate manufacturer specification. Use the interrupt only with the correct polarity and acknowledge sequence.
Compliance Information
The supplied verified data does not include explicit RoHS, REACH, lead-free, halogen-free, conflict-minerals, or AEC-Q100 declarations for PCF8574N. AEC-Q100 is marked not_applicable because no automotive qualification is stated.