PCF8574NE4 datasheet by Texas Instruments

PCF8574NE4 Frequently Asked Questions (FAQs)

• What is the maximum frequency of the I2C bus that the PCF8574NE4 can support?
  The PCF8574NE4 can support I2C bus frequencies up to 400 kHz, but it is recommended to operate at 100 kHz or lower for reliable operation.
• Can I use the PCF8574NE4 as a level shifter for 5V to 3.3V or vice versa?
  Yes, the PCF8574NE4 can be used as a level shifter, but it's not recommended as it's not designed for that purpose. The device is intended for I/O expansion and not for level shifting. Using it as a level shifter may lead to reliability issues.
• How do I handle the power-on reset (POR) of the PCF8574NE4?
  The PCF8574NE4 has a built-in power-on reset (POR) circuit that resets the device when the power supply voltage (VCC) rises above 0.5V. To handle POR, ensure that the I2C bus is not active during power-up, and wait for at least 100 μs after power-up before sending I2C commands.
• What is the maximum current that can be sourced or sunk by the PCF8574NE4?
  The PCF8574NE4 can source or sink up to 25 mA per I/O pin, but the total current sourced or sunk by all I/O pins should not exceed 100 mA.
• Can I use the PCF8574NE4 with a 5V microcontroller?
  Yes, the PCF8574NE4 is 5V tolerant, but it's recommended to use a level shifter or voltage divider to ensure that the I2C bus signals are within the recommended voltage range (VCC + 0.5V) to prevent damage to the device.