PCF8574ADW datasheet by Texas Instruments

PCF8574ADW Frequently Asked Questions (FAQs)

• What is the maximum frequency of the I2C bus that the PCF8574ADW can support?
  The PCF8574ADW can support I2C bus frequencies up to 400 kHz, but it's recommended to limit it to 100 kHz for reliable operation.
• How do I handle the internal pull-up resistors on the I/O pins?
  The internal pull-up resistors on the I/O pins are enabled by default. To disable them, set the corresponding bit in the configuration register (address 0x04) to 1. You can also use external pull-up resistors if needed.
• What is the maximum current that the PCF8574ADW can sink or source on each I/O pin?
  The PCF8574ADW can sink or source up to 25 mA of current on each I/O pin, but it's recommended to limit it to 10 mA for reliable operation.
• How do I reset the PCF8574ADW?
  The PCF8574ADW can be reset by pulling the RESET pin low for at least 1 ms. You can also reset the device by sending a reset command over the I2C bus (address 0x00, data 0x06).
• What is the purpose of the INT pin?
  The INT pin is an interrupt output that is asserted low when any of the input pins change state. It can be used to wake up a microcontroller from sleep mode or to trigger an interrupt.