PCF8574AT/3,518 datasheet by NXP Semiconductors

PCF8574AT/3,518 Frequently Asked Questions (FAQs)

• What is the maximum frequency of the I2C bus that the PCF8574AT can support?
  The PCF8574AT can support I2C bus frequencies up to 400 kHz.
• How do I reset the PCF8574AT?
  The PCF8574AT can be reset by pulling the SCL line low for at least 2 clock cycles.
• What is the maximum current that the PCF8574AT can sink or source per I/O pin?
  The PCF8574AT can sink or source up to 25 mA per I/O pin.
• Can the PCF8574AT be used in a 5V system?
  Yes, the PCF8574AT is 5V tolerant, but it is recommended to use a voltage regulator to ensure a stable 3.3V supply.
• How do I configure the PCF8574AT as an input or output?
  The PCF8574AT can be configured as an input or output by writing to the corresponding register. A '1' in the register sets the pin as an input, while a '0' sets it as an output.