Overview
The PCF8574PW, manufactured 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) pins. It operates within a voltage range of 2.5V to 5.5V, making it versatile for various applications. The PCF8574PW features an 8-bit quasi-bidirectional I/O port (P0–P7) with latched outputs, capable of directly driving LEDs without the need for a data-direction control signal. At power-on, the I/Os are set to high, with only a current source to VCC active in this mode.
Key Specifications
| Parameter | Value |
|---|---|
| Operating Voltage (VCC) | 2.5V to 5.5V |
| I/O Port | 8-bit quasi-bidirectional (P0–P7) |
| Interface | I2C (SCL, SDA) |
| Interrupt Output | Open-drain (INT) |
| Package Options | TVSOP (20-pin), SOIC (16-pin), PDIP (16-pin), TSSOP (20-pin), QFN (16-pin), VQFN (20-pin) |
| Body Size (Nominal) | Varies by package (e.g., TVSOP: 5.00 mm × 4.40 mm, SOIC: 10.30 mm × 7.50 mm) |
| Operating Temperature | -40°C to 85°C |
| ESD Ratings | Exceeds 2000V per MIL-STD-883, Method 3015; Exceeds 200V per Machine Model (C = 200 pF, R = 0 Ω) |
Key Features
- 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.
- Open-drain interrupt output (INT) that can be connected to the interrupt input of a microcontroller.
- Interrupt generation by any rising or falling edge of the port inputs in the input mode.
- Compatibility with most microcontroller families via the I2C interface.
Applications
- Telecom shelters: Filter units.
- Servers and routers (telecom switching equipment).
- Personal computers and personal electronics.
- Industrial automation.
- Products with GPIO-limited processors.
Q & A
- What is the operating voltage range of the PCF8574PW? The PCF8574PW operates within a voltage range of 2.5V to 5.5V.
- What type of interface does the PCF8574PW use? The PCF8574PW uses the I2C interface.
- How many I/O ports does the PCF8574PW have? The PCF8574PW has an 8-bit quasi-bidirectional I/O port (P0–P7).
- What is the purpose of the INT pin on the PCF8574PW? The INT pin is an open-drain interrupt output that can be connected to the interrupt input of a microcontroller.
- Can the I/O ports be used as inputs or outputs? Yes, the I/O ports can be used as inputs or outputs without the need for a data-direction control signal.
- What are some common applications of the PCF8574PW? Common applications include telecom shelters, servers, routers, personal computers, personal electronics, industrial automation, and products with GPIO-limited processors.
- What are the package options available for the PCF8574PW? The PCF8574PW is available in TVSOP, SOIC, PDIP, TSSOP, QFN, and VQFN packages.
- How is the interrupt reset on the PCF8574PW? The interrupt is reset when data on the port is changed to the original setting or when data is read from or written to the port that generated the interrupt.
- What is the operating temperature range of the PCF8574PW? The operating temperature range is -40°C to 85°C.
- What are the ESD ratings for the PCF8574PW? The PCF8574PW exceeds 2000V per MIL-STD-883, Method 3015, and exceeds 200V per Machine Model (C = 200 pF, R = 0 Ω).
