Texas Instruments

PCA9555PW

PCA9555PW Description

The PCA9555PW from Texas Instruments is a 16-bit I²C-bus and SMBus I/O expander designed for 2.3V to 5.5V voltage operation. Housed in a 24-pin TSSOP package, this surface-mount IC provides flexible bidirectional I/O expansion for microcontrollers via the I²C/SMBus interface (clock frequency up to 400 kHz). With 16 configurable I/O pins, each capable of sourcing/sinking 10mA (default) or 25mA (per-pin programmable), it is ideal for driving LEDs, sensors, or relays. The device includes Power-On Reset (POR) and interrupt output for efficient system monitoring. Though marked obsolete, it remains RoHS3 compliant and REACH unaffected, ensuring compatibility with modern environmental standards.

PCA9555PW Features

• 16 I/O Pins: Configurable as inputs or outputs with individually programmable pull-up/pull-down resistors.
• High Drive Capability: 10mA (default) or 25mA (per pin) for robust peripheral control.
• Wide Voltage Range: 2.3V–5.5V operation suits mixed-voltage systems.
• I²C/SMBus Interface: Supports 400 kHz clock frequency for fast communication.
• Interrupt Output: Minimizes MCU polling by signaling input state changes.
• Power-On Reset (POR): Ensures predictable startup conditions.
• Low Standby Current: Optimized for power-sensitive applications.

PCA9555PW Applications

• LED Matrix Control: Drives multiple LEDs with programmable current sink capability.
• Industrial Automation: Expands I/O for PLCs, sensors, and actuator interfaces.
• Consumer Electronics: Keypad scanning, display backlight control in smart devices.
• Embedded Systems: GPIO extension for microcontrollers with limited pins (e.g., Arduino, Raspberry Pi).
• Telecom Equipment: Hot-swappable module status monitoring via interrupt-driven alerts.

Conclusion of PCA9555PW

The PCA9555PW excels in I/O expansion for I²C/SMBus systems, offering high drive strength, low-voltage operation, and interrupt efficiency. Its obsolete status may limit new designs, but its robust feature set (e.g., POR, 25mA sink capability) makes it a reliable choice for legacy or cost-sensitive projects requiring 16-bit GPIO expansion. Ideal for LED control, industrial I/O, and embedded systems, it balances performance with ease of integration. Engineers should evaluate alternatives for future-proof designs but can leverage this IC for proven, stable performance in existing applications.