NXP PCA9545D 4-Channel I2C Multiplexer

The NXP PCA9545D is a master-driven multiplexer that provides 4 downstream channels to facilitate communication with multiple I2C devices that may otherwise have conflicting addresses. This IC is particularly useful in complex systems where the number of I2C devices exceeds the address space or when multiple identical devices must be accessed independently.

Key Features

• Four bidirectional translating switches: The PCA9545D offers four separate bidirectional translating switches that provide access to four downstream channels.
• 1-of-4 channel selection: Via the I2C bus, the user can select any combination of the four channels, enabling communication with multiple I2C devices.
• Active LOW interrupt input: An interrupt input is provided for each of the downstream channels, allowing for efficient communication with the host controller when an I2C device on any channel requires attention.
• Low standby current: The device is optimized for low power consumption, which is critical for battery-powered and energy-efficient applications.
• 5V tolerant inputs: Inputs can tolerate up to 5V even when the device is powered down, providing design flexibility and protection against higher voltage levels.
• Compliance: The PCA9545D is compliant with the I2C-bus Fast and Standard modes.

Applications

This multiplexer is suitable for a variety of applications, including, but not limited to, server motherboards, telecommunication systems, and consumer electronics where multiple I2C devices are used. It allows a single I2C master to interface with more I2C slaves than would otherwise be possible, by providing additional bus lines that can be selected as needed.

Package and Operation

The PCA9545D is offered in a 20-pin TSSOP (Thin Shrink Small Outline Package) which is designed for space-saving on PCBs. It operates over the -40°C to +85°C temperature range, making it suitable for industrial environments. The device also features an active LOW reset input that initiates a software reset, clearing all the registers and terminating any I2C communication, which is a useful feature during system errors or initializations.