Overview
The PCF8574N from Texas Instruments is an 8-bit I/O expander designed to provide general-purpose remote I/O expansion via the two-wire bidirectional I2C-bus. This device is part of TI's I2C logic portfolio and is intended for use with most microcontroller families. It operates within a supply voltage range of 2.5-V to 6-V, making it versatile for various applications. The PCF8574N is pin-to-pin compatible and functionally equivalent to the Philips PCF8574, with additional package options such as TVSOP, QFN, and TSSOP, offering smaller footprint solutions.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Operating Supply Voltage (VCC) | 2.5 to 6 | V |
| Operating Temperature Range | -40 to 85 | °C |
| I2C Bus Frequency | 100 kHz | Hz |
| Number of I/O Ports | 8 | - |
| I/O Port Type | Quasi-bidirectional | - |
| Interrupt Output Type | Open-drain, active LOW | - |
| Maximum Sinking Current per I/O | 25 mA | mA |
| Standby Current Consumption | 2.5 µA (typical, static) | µA |
| Package Options | PDIP, SOIC, TSSOP, TVSOP, QFN | - |
Key Features
- Two-wire I2C-bus to 8-bit bidirectional parallel-bus expander
- Latched outputs with high-current drive capability for directly driving LEDs
- Open-drain interrupt output to signal changes on I/O pins
- Three hardware address inputs allowing up to 16 devices on the same I2C bus
- Low standby current consumption suitable for mobile applications
- Internal Power-On Reset (POR) initializes I/Os as inputs with a weak internal pull-up current source
- Pin-to-pin compatible and functionally equivalent to Philips PCF8574 and PCF8574A
- Smaller package options such as TVSOP and QFN
Applications
- Fan control and monitoring
- LED drivers and displays
- System monitoring and diagnostics
- Temperature sensor monitoring
- Push button and keypad monitoring
- Servers and data centers
- Industrial control and automation
- Medical equipment and devices
- Cellular telephones and mobile devices
- Gaming machines and instrumentation
Q & A
- What is the PCF8574N used for?
The PCF8574N is used for general-purpose remote I/O expansion via the two-wire I2C-bus, allowing microcontrollers to monitor and control several peripheral signals.
- What is the operating voltage range of the PCF8574N?
The operating supply voltage range is from 2.5-V to 6-V.
- How many I/O ports does the PCF8574N have?
The PCF8574N has 8 quasi-bidirectional I/O ports.
- What is the maximum sinking current per I/O port?
The maximum sinking current per I/O port is 25 mA.
- Can multiple PCF8574N devices be used on the same I2C bus?
Yes, up to 16 devices (8 PCF8574 and 8 PCF8574A) can be used on the same I2C bus by setting unique addresses using the hardware address pins.
- What is the purpose of the interrupt output on the PCF8574N?
The interrupt output is used to signal changes on the I/O pins to the microcontroller without continuous polling.
- What are the package options available for the PCF8574N?
The package options include PDIP, SOIC, TSSOP, TVSOP, and QFN.
- How does the Power-On Reset (POR) function on the PCF8574N?
The POR initializes the I/Os as inputs with a weak internal pull-up current source.
- What are some common applications of the PCF8574N?
Common applications include fan control, LED drivers, system monitoring, temperature sensor monitoring, and industrial control.
- Is the PCF8574N compatible with other similar devices?
Yes, it is pin-to-pin compatible and functionally equivalent to Philips PCF8574 and PCF8574A devices.
