To USB or Not to USB

 

Simplest, Smartest and Lowest Cost USB Type-C

We have been seeing a lot of interest in all things USB Type-C from basic USB 2.0 Type-C support all the way to the higher end USB Type-C Alt Mode with DisplayPort. Actually, the latter is getting the most focus as it’s far more complex than traditional standalone USB operation and it’s a highly desirable use mode. Many of the questions are asking for our recommendation as to how to handle the high power, high voltage power delivery and Type-C Port Controller hardware. This is a complex HW partitioning, SW partitioning and system architecture question.

Type-C-Detail

We actually answered this and more in our recent web seminars but I wanted to share the key points in this blog.

Many years ago when we started the original solution development we pondered the architecture very carefully especially in the area of the Type-C Port controller and Power Delivery needs. Very quickly we drew our conclusion that these blocks did not belong in the SoC. The main reasons for this architectural decision is that newer SoC nodes such as 16nm FinFET are not suitable for the high power, high voltage requirements that the USB Spec puts on the blocks. Adding to this, the end product needs vary greatly changing what function would be needed. Many of todays designs target creating a single SoC with potentially multiple markets. If you hard code the TCPC and PD elements into the SoC this would restrict the use modes significantly.

The simple solution, have the TCPC and PD elements external to the SoC.

We were not the only company to come to this conclusion proven by the fact that there are a boat load of Type-C off-the-shelf chips available for this purpose. The SoC handles the main datapath operation and there is a simple interface from it to the external chips. Chip manufactures such as TI, Cypress, Fresco Logic, NXP, Fairchild, Microchip, Prolific, ST Micro, Pericom, Richtek, Weltrend, Analogix, VIA Labs, Paradetech, Canyon, Richtek, Fintek…… and the list goes on….  offer devices meeting the needs of many application spaces….

Type-C-system

There are three groups of chips depending on your system. The first and most basic is the Type-C Port Controller group, these offer basic configuration channel (CC) functionality. These include the Programmable Pull Resistors, CC Level Detection for cable orientation and current detection and typically have a GPIO/SPI/I2C interface to SoC. This is a very popular chip as it easily enables basic Type-C function.

Typical Basic Type-C Port Controller chip capabilities

Basic-CC-Chip

The next group enables additional capabilities specific to power delivery and power delivery messaging. You would select a chip like this is your design needs to support one of the alt modes for example

Typical Type-C Port Controller w/Embedded Type-C Port Manager chip capabilities

TCPC-Chip-W-embedded-TCPC

Finally these is the all singing, all dancing, advanced Type-C Port Controller & Port manager chips which add power supply and battery charger capabilities.

Typical advanced Type-C Port Controller & Port manager chip functionality

Advanced-Type-C-Chip

Based on the easy availability of off the shelf solutions you can see why you would never bother to design this into your SoC. When I made this statement last week in a customer meeting the customer said to me “but what about PCB BOM cost!”. Yes it’s a trade-off I responded. The cost of these devices are minimal but yes, increase your PCB BOM cost, however, it’s an insignificant cost to that of trying to design in this capability into your SoC. I then asked if they planned to design this into their SoC…… the answer…. NO WAY, it’s not worth their time or effort to put this capability into the SoC. In addition, this was a newer process node and not suitable for the high power, high voltage needs…. (Isn’t this what I said at the start…..)

The Synopsys solutions for USB Type-C and alt mode DisplayPort was designed to make use of these off the shelf solutions. This ensures that the SoC design delivers the maximum of flexibility enabling tailoring to meet the needs of multiple end markets and usage models.

Over the week of October 17th I also attended the USB-IF Hong Kong Developer days. The vendor participation also reflected the above information with many Type-C/PD chip providers showing off their solutions.

Here I am with the Synopsys Senior Product Manager for USB/DP Mixed Signal PHY products. In the middle you can see our USB 3.1 Gen 2 (10Gb/s) Type-C demo. Many customers were impressed with the full 10G transfer rates we were able to demonstrate in hardware as well as the USB Type-C cable flipping. We even ended up doing a little ad-lib plugfest slash performance bake-off with a number of the cable manufacturers. We plugged in a number of different cables and ran the performance tests between our systems, including flipping of the cable.

Booth

It was really great to interact with so many USB knowledgeable folks.

Interaction1

The only downside was that Hong Kong experienced a pretty bad Typhoon, Signal 8 status. The good news was that Hong Kong is very well prepared for such weather and did not sustain very much damage at all. Of course I will say seeing this sign as you check into your hotel is not comforting

Signal8

Ah the joys of business travel. All Synopsys employees made it home safe and sound.

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