Overview
The PCF8574AN, produced by Texas Instruments, is an 8-bit input/output (I/O) expander designed for use with the two-line bidirectional I2C bus. This device is intended for general-purpose remote I/O expansion for most microcontroller families via the I2C interface, which includes serial clock (SCL) and serial data (SDA) lines. It operates within a voltage range of 2.5V to 6V VCC, making it versatile for various applications. The PCF8574AN features an 8-bit quasi-bidirectional I/O port (P0–P7) with latched outputs, capable of driving LEDs directly due to its high-current drive capability.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Operating Voltage (VCC) | 2.5 to 6 | V |
| Operating Free-Air Temperature (TA) | -40 to 85 | °C |
| Standby Current Consumption | 10 | μA |
| High-Level Output Current (IOH) | -1 | mA |
| Low-Level Output Current (IOL) | 25 | mA |
| I2C Clock Low Time | 4.7 | μs |
| I2C Bus Capacitive Load (Cb) | 400 | pF |
| Junction-to-Ambient Thermal Resistance (RθJA) | 112.2 (20-pin), 76.7 (16-pin), 48.3 (16-pin), 94.8 (20-pin), 52.2 (20-pin) | °C/W |
Key Features
- Low standby-current consumption of 10μA max
- I2C to parallel-port expander
- Open-drain interrupt output
- Compatible with most microcontrollers
- Latched outputs with high-current drive capability for directly driving LEDs
- Quasi-bidirectional I/O ports (P0–P7) that can be used as inputs or outputs without a data-direction control signal
- Interrupt generation by any rising or falling edge of the port inputs in the input mode
Applications
- Telecom shelters: filter units
- Servers
- Routers (telecom switching equipment)
- Personal computers
- Personal electronics
- Industrial automation
- Products with GPIO-Limited Processors
Q & A
- What is the operating voltage range of the PCF8574AN?
The PCF8574AN operates within a voltage range of 2.5V to 6V VCC.
- What type of interface does the PCF8574AN use for communication?
The PCF8574AN uses the I2C interface, which includes serial clock (SCL) and serial data (SDA) lines.
- What is the standby current consumption of the PCF8574AN?
The standby current consumption is 10μA max.
- Can the PCF8574AN drive LEDs directly?
Yes, the PCF8574AN has latched outputs with high-current drive capability for directly driving LEDs.
- How does the interrupt output work on the PCF8574AN?
The PCF8574AN generates an interrupt by any rising or falling edge of the port inputs in the input mode. The interrupt is reset when data on the port is changed or read from/written to the port that generated the interrupt.
- What are some common applications of the PCF8574AN?
Common applications include telecom shelters, servers, routers, personal computers, personal electronics, industrial automation, and products with GPIO-limited processors.
- What is the thermal resistance of the PCF8574AN?
The junction-to-ambient thermal resistance (RθJA) varies by package, ranging from 48.3°C/W to 112.2°C/W.
- How does the power-on reset feature work on the PCF8574AN?
The power-on reset feature resets the device to its default conditions by cycling the power supply. This reset occurs during the initial power-on or in the event of a glitch or data corruption.
- What are the layout guidelines for using the PCF8574AN?
Best practices include using a 4-layer PCB with dedicated power and ground planes, placing capacitors close to the device to filter out high-frequency ripple, and using vias to connect to internal layers.
- Can the PCF8574AN be used with most microcontrollers?
Yes, the PCF8574AN is compatible with most microcontroller families.
