1 Introduction

The TPS65992S is a single-port USB Type-C and USB Power Delivery (PD) controller that integrates various digital interfaces for communication with other devices. Notably, TPS65992S provides three I2C ports: I2C1 and I2C2 function as I2C peripheral interfaces (for host or EC communication), and I2C3 serves as an I2C controller. This I2C controller port allows the TPS65992S to directly control external components on the board. In the design discussed here, I2C3 is used to manage two key devices: the TPS55288 buck–boost converter and the TUSB1044 linear redriver.

The TUSB1044 is a USB Type-C Alternate Mode redriver-switch (a linear repeater for high-speed signals) that supports SuperSpeed data rates up to 10Gbps and is protocol-agnostic. This means TUSB1044 can pass USB3.1 Gen2 signals and also route DisplayPort lanes over the USB-C connector in DisplayPort Alternate Mode. The device can be configured either through fixed pin settings or through an I2C interface for dynamic control. The internal registers allow control of operating modes, flipping of high-speed lane mapping, equalization (EQ) settings, and other features (see the TUSB1044 data sheet register map for details). Using the TPS65992S as an I2C controller, the system can command the TUSB1044 to switch between USB3-only operation and various DisplayPort Alt Mode configurations depending on the cable orientation and negotiated mode.

The TPS55288 is a synchronous four-switch buck–boost converter designed for USB Power Delivery source applications. The TPS55288 can regulate the output voltage below, equal to, or above the input voltage, supporting a wide input range (2.7V to 36V) and an output range from 0.8V up to 22V. The TPS55288 features a 10-bit DAC for setting the internal reference voltage that determines the output level, with 1 LSB ≈ 1.129mV. Through the I2C interface, the output voltage and current limit can be programmed, enabling compliance with USB PD requirements (including Programmable Power Supply [PPS]). In practice, this converter can deliver up to 100W (for example, 20V at 5A) from a typical 12V source. Key configuration registers on the TPS55288 include the REF registers (0x00 and 0x01) which set the internal reference voltage, the IOUT_LIMIT register (0x02) for current limit, and others for slew rate, feedback selection, and so on. For example, the REF registers (0x00/0x01) form a 10-bit value that programs the converter reference voltage; writing the appropriate value adjusts the output voltage according to the internal feedback ratio.

This application note describes how the TPS65992S PD controller I2C3 controller interface is configured to control the TPS55288 and TUSB1044 in a coordinated manner. We explain the necessary settings in the TPS65992S Application Customization Tool, the configuration of I2C command sequences (with proper peripheral addresses and register addresses), and the event-triggered I2C transactions that allow these devices to function seamlessly during PD negotiation and USB-C Alternate Mode operation. Each section below covers the setup for the power converter and redriver, respectively, followed by a summary of all I2C events used in this design.