How to Test USB Power Delivery Over the Type-C Connector

Application Notes

This application note is one in a series of five covering the challenges and solutions for USB Type-C design and test. 

  • cable and connector 
  • power delivery 
  • transmit/receive 
  • simulation-measurement correlation 
  • Alternate Mode (ALT)(DisplayPort, Thunderbolt, MHL) 

Introduction 

USB Type-C is a breakthrough standard designed to meet the demand for technology that supports compact and ultra-thin computers and devices, high-speed data, and more power. Key USB Type-C areas of focus include the connection between devices, managing power, and ensuring valid data transmissions. The USB Type-C connection provides

  • dynamic power and transmission of USB 2.0 with other protocols 
  • key interface for current and future devices 
  • backward compatibility 
  • reversibility enables ease-of-use 

Design and test engineers face several challenges as they integrate USB Type-C into their products while ensuring interoperability and test compliance. USB Type-C compliance test standards are more complex due to higher data transmission speeds, more power, and additional functionality. Successful testing requires highly accurate and standard-compliant test instruments, software, and fixtures. 

Type-C Power Delivery 

The USB Type-C connection has broadened the range of USB usability by incorporating a dynamic power system called Power Delivery (PD). Increased USB capability is achievable by providing up to 20 volts, 5 amps, and 100 watts for powering and charging many more device types including expanded data transfer capabilities. The USB power delivery’s intelligent and flexible system-level power management supports 

bidirectional power that can switch direction for the connected provider (sourcing power) and consumer (sinking power) devices. This dynamic power makes it possible for the USB Type-C to support other standards for video and audio signals, such as DisplayPort or Thunderbolt, through the ALT mode.

How Power Delivery Works 

The end-to-end USB Type-C connection is made between devices, and cable orientation is determined through the configuration channel (CC) line. The USB connection initialization begins with the power delivery. The power delivery learns the functionality of the connected cable through an electronic connection between the power delivery circuit and any full-featured Type-C cable, which includes an E-mark chip. The E-mark chip provides cable configuration information and is recognizable electronically and configured to its current carrying capability (3 A or 5 A), performance (USB 2.0 or USB 3.1, Gen 1 or Gen 2), and vendor identification (USB Type-C cable ID function). Following the cable recognition, the power delivery circuit and the connected device use the dedicated CC1 / CC2 lines to send and receive biphase marked coding (BMC) messages to begin the power negotiation process. 

Flexible bidirectional charging is new to USB Type-C and is now possible using the power delivery’s dynamic control of higher voltage and currents. The power delivery can quickly charge device batteries using its charge adapter, which is capable of outputting different and higher voltage levels from 5 V up to 20 V, and current of either 3 A or 5 A, depending on the Type-C cable and connector. Devices can request a higher voltage when they are charging using CC1 / CC2 lines. 

When a device charges, all other connected devices must negotiate the amount of power required. Devices can renegotiate power if another device requires additional power. Power delivery can also optimize to a lower battery voltage and higher charging current, making the recharging time much faster. The bidirectional power makes it possible to supply power to several devices. In addition to the power management of connected devices, the power delivery also manages power to support Type-C Alternate modes (ALT). 

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