PCA9955ATWJ datasheet by NXP Semiconductors

PCA9955ATWJ Frequently Asked Questions (FAQs)

• What is the maximum current that the PCA9955ATWJ can sink or source per output?
  The PCA9955ATWJ can sink or source up to 10mA per output, but it's recommended to limit the current to 5mA per output to ensure reliable operation.
• How do I ensure that the PCA9955ATWJ is properly powered up and initialized?
  To ensure proper power-up and initialization, make sure to follow the recommended power-up sequence, which includes applying VCC, then VEE, and finally the clock signal. Also, ensure that the reset pin is properly tied to VCC through a pull-up resistor.
• What is the maximum clock frequency that the PCA9955ATWJ can operate at?
  The PCA9955ATWJ can operate at clock frequencies up to 25MHz, but it's recommended to operate at 10MHz or lower to ensure reliable operation and minimize power consumption.
• How do I configure the PCA9955ATWJ for 8-bit or 16-bit bus width?
  The PCA9955ATWJ can be configured for 8-bit or 16-bit bus width by setting the appropriate values on the A0 and A1 address pins. For 8-bit bus width, tie A0 and A1 to GND, and for 16-bit bus width, tie A0 to VCC and A1 to GND.
• What is the purpose of the internal oscillator on the PCA9955ATWJ?
  The internal oscillator on the PCA9955ATWJ is used to generate the clock signal for the device when an external clock is not provided. However, it's recommended to use an external clock source for more accurate and reliable operation.