NXP PCA9536DP 4-bit I²C-bus I/O Expander, TSSOP Package

The NXP PCA9536DP is a 4-bit CMOS I²C-bus and SMBus I/O Port integrated circuit designed to provide general-purpose parallel input/output (GPIO) expansion for microcontroller-based systems. It enhances a system's capability by adding four configurable I/O lines through a simple two-wire serial interface, solving the common problem of needing additional I/O for peripherals without consuming valuable processor pins.

This expander is built around a flexible register set, including a 4-bit configuration register (for selecting input or output mode), a 4-bit input port register, a 4-bit output port register, and a 4-bit polarity inversion register. The system master (like a microcontroller) can dynamically configure each of the four I/O pins as an input or an output. The polarity inversion feature allows the logic level of the input register to be inverted, supporting both active-high and active-low operation for connected devices such as sensors, switches, or LEDs.

Key Features & Benefits

• Simplified Design: Provides a straightforward solution for adding I/O capacity to I²C-bus or SMBus applications.
• Low Power Consumption: Features low standby current, making it suitable for power-sensitive designs.
• Robust Operation: Includes a noise filter on the SCL and SDA input lines for improved communication reliability in electrically noisy environments.
• Stable Power-Up: Engineered for no glitch during power-up and includes an internal power-on reset circuit, ensuring predictable initialisation.
• Compact Form Factor: Housed in a space-saving TSSOP (Thin Shrink Small Outline Package).

Primary Applications

This I/O expander is ideal for a wide range of electronic applications where additional digital control or monitoring lines are required. Common uses include interfacing with ACPI power switches, reading from various sensors (like temperature or tam