Overview
The PCF8574NG4, produced by Texas Instruments, is an 8-bit remote I/O expander designed for use with the I2C bus interface. This device provides general-purpose remote I/O expansion for most microcontroller families, operating within a voltage range of 2.5 V to 6 V. It features an 8-bit quasi-bidirectional I/O port (P0–P7) and an open-drain interrupt output (INT) that can be connected to the interrupt input of a microcontroller. The PCF8574NG4 is suitable for various applications requiring additional I/O ports and efficient communication via the I2C interface.
Key Specifications
| Parameter | Description | Value |
|---|---|---|
| VCC Operating Voltage | Supply voltage range | 2.5 V to 6 V |
| I/O Port Type | Quasi-bidirectional I/O ports | P0–P7 |
| I2C Bus Interface | Serial clock (SCL) and serial data (SDA) | Up to 100 kHz |
| Interrupt Output | Open-drain interrupt output (INT) | Active LOW |
| Address Inputs | Hardware address inputs | A0, A1, A2 |
| Operating Temperature | Free-air temperature range | –40°C to 85°C |
| Supply Current | Typical static supply current | 2.5 µA |
| Latch-Up Performance | Exceeds 100 mA per JESD 78, Class II |
Key Features
- Quasi-Bidirectional I/O Ports: Each I/O can be used as an input or output without the need for a data-direction control signal.
- Open-Drain Interrupt Output: The INT output can be connected to the interrupt input of a microcontroller to indicate changes in the input state.
- Latched Outputs: High-current drive capability for directly driving LEDs.
- I2C Interface: Supports up to 100 kHz I2C bus interface.
- Hardware Address Inputs: Three address inputs (A0, A1, A2) allowing up to 16 devices on the same I2C bus.
- Low Current Consumption: Typical static supply current of 2.5 µA, suitable for mobile applications.
- Power-On Reset: Initializes I/Os as inputs with a weak internal pull-up current source.
Applications
- Telecom Shelters and Equipment: Filter units, servers, routers, and telecom switching equipment.
- Personal Computers and Electronics: Expanding I/O capabilities in personal computers and other electronic devices.
- Industrial Automation: Used in industrial control systems, PLCs, and other automation equipment.
- Medical Equipment: Suitable for use in medical devices requiring additional I/O ports.
- Mobile Devices and Gaming Machines: Ideal for mobile applications due to low current consumption.
- Instrumentation and Test Measurement: Used in various measurement and testing equipment.
Q & A
- What is the operating voltage range of the PCF8574NG4?
The operating voltage range is 2.5 V to 6 V.
- How many I/O ports does the PCF8574NG4 have?
The device has 8 quasi-bidirectional I/O ports (P0–P7).
- What is the purpose of the INT output?
The INT output is an open-drain interrupt output that indicates changes in the input state to the microcontroller.
- What is the maximum frequency of the I2C bus interface?
The I2C bus interface supports up to 100 kHz.
- How many devices can be connected on the same I2C bus?
Up to 16 devices can be connected on the same I2C bus using the three hardware address inputs.
- What is the typical static supply current of the PCF8574NG4?
The typical static supply current is 2.5 µA.
- What is the operating temperature range of the PCF8574NG4?
The operating temperature range is –40°C to 85°C.
- Can the PCF8574NG4 directly drive LEDs?
Yes, the latched outputs have high-current drive capability for directly driving LEDs.
- What happens during power-on reset?
The I/Os are initialized as inputs with a weak internal pull-up current source.
- What are some common applications of the PCF8574NG4?
Common applications include telecom equipment, personal computers, industrial automation, medical equipment, and mobile devices.
