This 16-bit I/O expander for the two-line bidirectional bus (I2C) is designed for 1.65-V to 5.5-V VCC operation. It provides general-purpose remote I/O expansion for most microcontroller families via the I2C interface.
The TCA9555 consists of two 8-bit Configuration (input or output selection), Input Port, Output Port, and Polarity Inversion (active high or active low operation) registers. At power on, the I/Os are configured as inputs. The system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration bits. The data for each input or output is kept in the corresponding Input or Output register. The polarity of the Input Port register can be inverted with the Polarity Inversion register.
The TCA9555 is identical to the TCA9535, except for the inclusion of the internal I/O pull-up resistor, which pulls the I/O to a default high when configured as an input and undriven.
Three hardware pins (A0, A1, and A2) are used to program the I2C address, which allows up to eight TCA9555 devices to share the same I2C bus or SMBus. The fixed I2C address of the TCA9555 is the same as the PCF8575, PCF8575C, and PCF8574, allowing up to eight of these devices in any combination to share the same I2C bus or SMBus.
| Top documentation | Type | Title | Format options | Date |
|---|---|---|---|---|
| * | Data sheet | TCA9555 Low-Voltage 16-Bit I2C and SMBus I/O Expander with Interrupt Output and Configuration Registers datasheet (Rev. E) | PDF | HTML | Apr 1, 2019 |
| Application note | How to Configure an I2C Push-Pull IO Expander to Operate as Open Drain | PDF | HTML | Jul 17, 2024 | |
| Application note | I2C: What is the Auto Increment Feature? | PDF | HTML | Jul 5, 2024 | |
| Application note | Understanding Transient Drive Strength vs. DC Drive Strength in Level-Shifters (Rev. A) | PDF | HTML | Jul 3, 2024 | |
| Application note | I2C Dynamic Addressing | Apr 25, 2019 | ||
| Application note | Choosing the Correct I2C Device for New Designs | PDF | HTML | Sep 7, 2016 | |
| Application note | Understanding the I2C Bus | PDF | HTML | Jun 30, 2015 | |
| Application note | I2C Bus Pull-Up Resistor Calculation | PDF | HTML | Feb 13, 2015 |
For additional terms or required resources, click any title below to view the detail page where available.
The IO expander evaluation module (EVM) lets you evaluate TI's portfolio of SMBus and I2C IO expander line devices. The TCA6424A and TCA9539 come installed on the board. The 24-pin TSSOP footprint also supports TCA6408A, TCA6416A, TCA9534, TCA9534A, TCA9535, TCA9538, TCA9554, TCA9554A and TCA9555.
| Package | Pins | CAD symbols, footprints & 3D models |
|---|---|---|
| SSOP (DB) | 24 | Ultra Librarian |
| VQFN (RGE) | 24 | Ultra Librarian |
| WQFN (RTW) | 24 | Ultra Librarian |
| TSSOP (PW) | 24 | Ultra Librarian |
Recommended products may have parameters, evaluation modules or reference designs related to this TI product.
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