NXP PCA9559 Low Voltage 16-bit I2C-bus and SMBus I/O Expander

The NXP PCA9559 is a versatile 16-bit I/O expander designed to provide a simple solution for expanding I/O capabilities via the I2C-bus and SMBus. This powerful device is ideal for applications where I/O pins on a microcontroller are limited and additional inputs/outputs are necessary. The PCA9559 operates at low voltages ranging from 2.3V to 5.5V, making it suitable for a wide variety of applications in the consumer, industrial, and automotive sectors.

One of the key features of the PCA9559 is its built-in level shifting capability, which allows it to interface with different logic levels, thus facilitating communication between devices operating at different voltages. This makes the PCA9559 an excellent choice for multi-voltage systems or for bridging devices that do not share the same operating voltage.

The PCA9559 provides 16-bit of General Purpose parallel Input/Output (GPIO) expansion through its two 8-bit Configuration (Input or Output selection), Input, Output, and Polarity Inversion (active HIGH or active LOW operation) registers. Each I/O can be configured independently, providing the user with the flexibility to address a wide range of applications. Additionally, the PCA9559's I/Os can sink or source up to 25 mA, allowing them to drive LEDs or other low-power devices directly.

With its built-in oscillator, the PCA9559 does not require an external clock, which simplifies the design and reduces the component count. The device also features an interrupt output that can be connected to the interrupt logic of the host microcontroller. When any input state differs from its corresponding Input Port register state, the device triggers an interrupt, thereby reducing the need for the microcontroller to poll the expander.

For addressing, the PCA9559 offers three hardware address pins, allowing up to eight devices to share the same I2C-bus or SMBus, which is particularly useful in complex systems that require a large number of I/Os. The PCA9559 is also equipped with a power-on reset feature, ensuring that the I/Os are configured as inputs at power-up.

In summary, the NXP PCA9559 is a flexible, low-voltage I/O expander that is easy to interface with and is perfect for expanding the I/O functionality of any I2C or SMBus-compatible device.