PCAL9555APW,118

I/o Expanders Overview

The PCAL9555APW,118 is a low-voltage 16-bit General Purpose Input/Output (GPIO) expander with interrupt and weak pull-up resistors for I2C-bus/SMBus applications. It operates within a supply voltage range of 1.65 V to 5.5 V and supports up to 400 kHz Fast-mode communication. The device features Agile I/O capabilities, including programmable output drive strength, latchable inputs, programmable pull-up/pull-down resistors, maskable interrupts, and an interrupt status register. It provides open-drain or push-pull outputs with a maximum sink capability of 25 mA. The component is housed in a TSSOP24 package and includes Schmitt-trigger action on SCL and SDA inputs for improved noise immunity.

I/o Expanders Feature Summary

• Agile I/O functionality enabling independent configuration of output drive strength, input latching, and internal pull-up/down resistors
• Interrupt masking and status registers allow selective monitoring of input state changes without spurious signals at power-up
• Open-drain active LOW interrupt output notifies the system master of input changes without continuous bus polling
• Internal weak pull-up resistors are enabled at power-on to replace external components

I/o Expanders Applications

• ACPI power switches
• Sensor interface expansion
• Push button matrix scanning
• LED driving and control
• Fan control systems

I/o Expanders Procurement Notes

Verify the ordering suffix ,118 corresponds to the TSSOP24 package variant when sourcing. Confirm that the specific revision matches the required Agile I/O feature set compared to standard PCA9555 devices. Ensure the supplier provides documentation confirming RoHS compliance and the correct temperature range specifications for the intended operating environment.

I/o Expanders Selection Notes

Select this component when software backward compatibility with PCA9555 is required alongside enhanced Agile I/O features. It is suitable for designs needing reduced rise and fall times through programmable drive strengths or those requiring input state latching to prevent missed interrupts. Verify that the 1.65 V minimum supply voltage aligns with the target microcontroller's logic levels.

I/o Expanders Part Context

The PCAL9555A series serves as a pin-to-pin replacement for the PCA9555 and PCA9555A families while introducing additional configurability. Unlike its predecessors, it powers up with all I/O interrupts masked to prevent spurious signals during board bring-up. This evolution allows designers to maintain existing hardware layouts while leveraging advanced GPIO management features such as individual bit-wise programming and configurable output stages.

I/o Expanders Replacement Considerations

PCAL9555AHF,128 is a direct pin-compatible alternative available in the HWQFN24 package.