Part Number: TCA9534APWR

Manufacturer: Texas Instruments

Description: IC XPNDR 400KHZ I2C 16TSSOP

Shipped from: Shenzhen/HK Warehouse

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The demand for diverse and efficient solutions to enhance input and output capabilities has become increasingly important in the ever-changing world of electronics. Enter the TCA9534APWR, an 8-bit I/O expander that enhances your project’s capabilities. In this detailed tutorial, we will explore the TCA9534APWR’s features, uses, and best practices to maximize its potential.

Understanding the TCA9534APWR

The TCA9534APWR is a 16-pin device that expands general-purpose parallel I/O by 8 bits. It operates seamlessly within the I2C bus (or SMBus) protocol, providing adaptability for various applications. Let’s dissect its main characteristics:

Voltage Flexibility

The TCA9534APWR has a wide power supply voltage range, from 1.65 V to 5.5 V, allowing it to work with a variety of devices.

Clock Frequencies

This device supports both 100-kHz (Standard-mode) and 400-kHz (Fast-mode) clock frequencies, ensuring efficient communication with your microcontroller and peripheral devices.

I/O Expansion

● Input Mode

When an I/O is configured as an input, FETs Q1 and Q2 are turned off, resulting in a high-impedance input. This means the input pin has minimal impact on the connected circuit and can handle external voltages up to 5.5 V, ideal for projects with varying voltage levels.

● Output Mode

In output mode, depending on the output port register’s state, either Q1 or Q2 is enabled, providing low-impedance paths to VCC or GND. Ensure that external voltage applied to this I/O pin stays within recommended levels for proper device operation.

● Interrupt Functionality

The TCA9534APWR offers interrupt capability, generating signals on the INT pin. This notifies your master controller when input port states change, enabling timely responses to events.


● Addressing Flexibility

With hardware-configurable address pins (A0, A1, and A2), you can connect up to eight TCA9534APWR devices on the same I2C bus, facilitating scalability for large projects.

● Reset Mechanism

Reset the device to its default state by cycling the power supply and initiating a power-on reset, simplifying setup management.

● Low Standby Current Consumption

Designed for energy efficiency, the TCA9534APWR boasts low standby current consumption, reducing power usage during idle periods.

● Noise Filtering

Incorporating a noise filter on SCL/SDA inputs eliminates interference and glitches during data transfer, ensuring reliable communication.

Applications of the TCA9534APWR

Now that we’ve covered the basics, let’s explore real-world uses for the TCA9534APWR:

● LED Management

The TCA9534APWR’s high-current drive capabilities make it perfect for directly driving LEDs, simplifying LED control for lighting systems or indicator panels.

● Integration of Sensors

Easily integrate multiple sensors into your projects. The TCA9534APWR’s I/O extension capabilities provide a versatile platform for sensor interfacing, whether it’s temperature sensors, motion detectors, or environmental sensors.

● HMI (Human-Machine Interface)

Enhance user interaction by incorporating pushbuttons and switches into your designs. The TCA9534APWR enables you to expand the number of inputs for HMI applications.

● Power Administration

Utilize the device for power management tasks like fan control and voltage monitoring, thanks to its wide voltage range and efficient I/O handling.

Best Practices for Using the TCA9534APWR

Consider these best practices to maximize the TCA9534APWR’s potential:

● Addressing

Plan your addressing strategy carefully to accommodate multiple devices on the same I2C bus, preventing address conflicts by utilizing hardware address pins (A0, A1, and A2).

● Restarting the Device

When necessary, employ the power-on reset option to ensure the device restarts in a known condition after power cycling.

● Handling Interrupts

Use interrupts to swiftly respond to changes in input states, enhancing application responsiveness.

● Current Limitations

Keep latch-up performance and maximum current capacities in mind to avoid overloading the device.

● Energy Conservation

Leverage the low standby current consumption to reduce power usage in battery-powered applications.

Functional Modes and Programming of the TCA9534APWR

The TCA9534APWR is an I/O expander with multiple functional modes and configurable features. Understanding these modes and how to communicate with the device via the I2C interface is crucial for harnessing its capabilities. In this section, we’ll examine the device’s functional modes, power-on reset behavior, and I2C programming.

Functional Modes

● Power-On Reset

Upon connecting power to the VCC pin, the TCA9534APWR undergoes a power-on reset procedure. This reset condition persists until VCC exceeds the VPORR (Power-On Reset Release Voltage) threshold. Resetting the device involves lowering VCC to VPORF (Power-On Reset Falling Voltage) and then raising it to the operational voltage.

Programming via I²C Interface

I² C Interface

The TCA9534APWR uses a bidirectional I2C interface that is managed by a master device. This master device connects with the TCA9534APWR to configure its settings or read its status. It is commonly a microcontroller or another controller. Each slave device on the I2C bus is issued a unique device address.

This device address is critical for distinguishing between slave devices, especially when numerous slave devices use the same I2C bus. The distinct device address ensures that the master device may communicate with the desired slave device. Many slave devices, including the TCA9534APWR, require configuration when they first power on. This configuration is usually performed when the master device accesses the slave’s internal register map.

The register map provides unique register addresses that allow the master to read or write data to the device in order to configure it. Depending on the device, the register map may contain one or more registers where data is saved, written, or read. These registers store configuration settings, status information, or device-related data.

Understanding these functional modes and the I2C interface allows you to properly program and manage the TCA9534APWR to meet the needs of your project. A solid understanding of these functionalities is required for proper integration and operation, whether you need to configure I/O pins, read input statuses, or control interrupts.


The TCA9534APWR stands as a versatile I/O expander, serving as a catalyst for electronics enthusiasts and engineers to effortlessly amplify the capabilities of their projects. Whether you’re orchestrating LED displays, weaving in sensory intricacies, or refining human-machine interfaces, this device emerges as an indispensable asset in your toolkit. By delving into its multifaceted features, exploring its myriad applications, and adopting best practices, you can harness its full potential and elevate your electronic designs to unprecedented heights.

Ready to embark on this transformative journey? To delve deeper into the possibilities presented by this groundbreaking device or to secure your order, reach out to ICRFQ, your trusted partner in electronic components. Our mission is to empower you in unlocking the TCA9534APWR’s limitless potential and ensuring the triumph of your projects. Connect with us today to kick start your voyage towards pioneering power control solutions, where potential metamorphoses into reality. Let us collaborate to bring your innovations to life.

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