PCA9535CPW,118

I/o Expanders Overview

The PCA9535CPW,118 is a 24-pin CMOS device providing 16 bits of General Purpose parallel Input/Output expansion for I2C-bus/SMBus applications. It operates within an operating power supply voltage range of 2.3 V to 5.5 V and supports clock frequencies from 0 Hz to 400 kHz. The component features high-impedance open-drain outputs on all I/O pins, which reduces power consumption when held LOW compared to the standard PCA9535. It includes an active LOW interrupt output that activates upon input state changes. The device is housed in a TSSOP24 package with a body width of 4.4 mm.

I/o Expanders Feature Summary

• High-impedance open-drain I/O configuration
• Active LOW interrupt output capability
• Polarity inversion register support

I/o Expanders Applications

• ACPI power switches
• Sensor interface connections
• Push button scanning
• LED control circuits
• Fan speed monitoring

I/o Expanders Procurement Notes

Verify the specific ordering suffix ',118' corresponds to the required reel packing method (Reel 13" Q1/T1) as indicated in the manufacturer's ordering information. Confirm the TSSOP24 package variant matches the design footprint requirements. Ensure the high-impedance open-drain nature of the PCA9535C series aligns with the external pull-up resistor strategy intended for the target application circuit.

I/o Expanders Selection Notes

Select this component over the standard PCA9535 when minimizing power consumption during low-level I/O states is critical, due to the removal of internal pull-up resistors. Verify compatibility with the system's I2C bus address constraints, as three hardware pins allow up to eight devices to share the same bus. Ensure the 5 V tolerant I/Os meet the voltage levels of the connected peripherals.

I/o Expanders Part Context

This part belongs to the NXP PCA9535 family of 16-bit I/O expanders. The 'C' designation specifically denotes the variant with high-impedance open-drain outputs, distinguishing it from the standard PCA9535 which retains internal pull-ups. It shares pin-to-pin and I2C address compatibility with the PCF8575 and PCA9555 families, though software adjustments are required due to architectural enhancements.

I/o Expanders Replacement Considerations

PCA9535PW,118

I/o Expanders FAQ

How does the PCA9535C differ electrically from the standard PCA9535?

The PCA9535C removes the internal I/O pull-up resistors found in the standard PCA9535, resulting in high-impedance open-drain outputs that significantly reduce power consumption when I/Os are held LOW.

What is the default state of the I/O pins at power-on reset?

At power-on reset, all 16 I/O pins default to input mode with high-impedance output drivers.

How is the interrupt signal generated and cleared?

The open-drain interrupt output activates when any configured input pin changes state. It deactivates when the input returns to its previous state or when the corresponding Input Port register is read by the master.