Tag Archives: USB Type-C

USB Type C and USB 3.1 Gen 2 – What is the Difference?

With the need for increasing capabilities, USB technology has evolved and improved over several years. Recently, the USB Implementation Forum has released the specifications for the SuperSpeed+1 standard or USB 3.1 Gen 2 signal standard and the USB Type C connector. Data transfer rates have been increasing from USB 1.0, released in January 1996, with a full speed of 1.5 MB/s, to USB 2.0, released in April 2000, with full speed of 60 MB/s, and to USB 3.0, released in Nov 2008, with a full speed of 625 MB/s. The latest standard, USB 3.1 Gen 2 was released in Jul 2013, and has a full speed of 1.25 GB/s.

Confusion between USB Type C and USB 3.1 Gen 2

When discussing the relationship, people are often confused between the USB Type C and the USB 3.1 Gen 2 standard. The major point to note is the USB Type C standard defines the physical connector alone, whereas the USB 3.1 Gen 2 standard defines the electrical signal for communication.

Therefore, system designers have the freedom to select signals conforming to USB 3.1 Gen 2 to pass through USB Type C connectors and cables or through a connector that do not conform to the USB Type C specification. Designers can implement their own proprietary connector and still use the USB 3.1 Gen 2 signal standard in case they want to use their own hardware or to ensure their system remains isolated from other systems.

The reverse is also equally true and applicable. One can use the USB Type C connector to transmit and receive signals that do not conform to the USB signal standards. Although the implementation will benefit from the inexpensive and easily available USB Type C connectors and cables, the OEM must label it correctly, since the user will be at the risk of connecting the proprietary non-conforming system to a USB 3.1 Gen 2 standard system and damaging one or both the systems.

OEMs can also transmit legacy USB signaling configurations using the USB Type C connectors and cables. This is because the USB standard allows using pre-USB 3.1 Gen 2 on USB Type C connectors, as they have designed the standard to cause no damage to either system. However, the most optimum power and data transfer will occur only when both systems are negotiating a common power configuration and communication standard.

Why USB Type C

Compared to the older configurations, the use of the USB Type C connector offers several advantages. Apart from being a smaller package with more conductors, the USB Type C supports higher voltage and current ratings, while offering greater signal bandwidths.

Physically smaller, the USB Type C plugs and receptacles fit in a wide range of applications where space is restricted. Moreover, one can connect the plugs and receptacles any way—either right-side up or up-side down. This allows easier and faster insertions of plugs into their receptacles.

While USB Type A and B connectors can have a maximum of four or five conductors, there are 24 contacts within the USB Type C and it can carry 3 A at 5 V, or 15 W of power.

What is USB Type-C Interface?

All new electronic devices are now coming with the USB-C interface, and this is revolutionizing the way people charge the devices. So far, most electronic devices had the micro-USB type-B connectors. With the USB Type-C connector, it is immaterial what orientation you use for the charging cable—the non-polarized connector goes in either the right side up or upside down. The connecting system is smart enough to figure out the polarity as a part of the negotiation process, and supports bidirectional power flow at a much higher level.

Earlier, the USB connectors handled only the 5 VDC fed into them. The USB-C port can take in the default 5 V, and depending on the plugged in device, raise the port voltage up to 20 V, or any mutually agreed on voltage, and a preconfigured current level. The maximum power delivery you can expect from a USB-C port is 20 V at 5 A or 100 W. This is more than adequate for charging a laptop. No wonder, electronic device manufacturers are opting for incorporating the USB-C into their next-generation products.

With the increasing power delivery through the USB Type-C ports, the computer industry has had to raise the performance requirement of the voltage regulator. Unlike the USB Type-B and the USB Type-A fixed voltage ports, the USB Type-C is a bidirectional port with a variable input, and an output range of 5-20 VDC. This adjustable output voltage feature allows manufacturers of notebooks and other mobile devices to use USB Type-C ports to replace the conventional AC/DC power adapters and USB Type-B and A terminals. Manufacturers are taking advantage of these features and incorporating dual or multiple USB Type-C ports into their devices.

However, using the current system architecture for implementing dual or multiple USB Type-C ports, leads to a complicated situation. It is unable to meet many requirements of the customers. As a solution, Intersil has proposed a new system architecture using the ISL95338 buck-boost type of regulator, and the ISL95521A, which is a combo battery charger. Use of these devices simplifies the design of the USB-C functions and fully supports all features. Applied on the adapter side, manufacturers can implement a programmable power supply, and it offers an adjustable output voltage that matches the USB-C variable input voltage.

In the proposed design, Intersil offers an architecture with two or more ISL95338 devices in parallel. Each of them interfaces a USB Type-C port to the ISL95521A battery charger. As this architecture eliminates several components from the conventional charging circuit, including individual PD controllers, ASGATE and OTG GATEs, it saves manufacturers significant costs. For charging a battery, power is drawn directly from the USB-C input to the ISL95521A, and the multiple ISL95338s offer additional options.

For instance, the user can apply two or more USB-C inputs with different power ratings for charging the battery fast. Therefore, the battery charge power is now higher than that supplied by a single USB-C input power. It also means there is no need for adding external circuitry to determine the different power rating operations of the paralleled ISL95338 voltage regulators.