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TPS65982: Use TPS65982 to detect between USB2.0 or USB3.0

1898541
Expert 1105 points
Part Number: TPS65982
Other Parts Discussed in Thread: TPS65983B

Hi,

I had a question for one of my designs. I need to design a device, which would use USB2.0 to communicate with my PC.

This would look something like:

Now because I would have the option to connect to both USB2.0 port (500mA) or a USB3.0 port (900mA/1.5A), I was looking for a solution where I can detect ports and negotiate for highest available power.

Would TPS65982  work here?

 

Thanks,

AQ

 

  • 0
    TI__Mastermind 36756 points
    Hi AQ,

    Are you required to provide more than 5V/3A?
    Does your system require the use of a USB Type-C connection?
    I'd like to know more about your system requirements so I can better provide a suggestion.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Expert 1105 points
    Hi Eric,
    Thanks for a reply. My system can make use of the 20V supply from USB. My weakest link here is the cable. I cannot have USB3.0 cable or a Type-C connector. I would be using 4 pin only.
    USB-PD can deliver power over VBus. I am interested to make use of that portion. For the communication protocol, i guess Ill have to fall back on USB2.0.

    Thanks,
    AQ
  • 0 in reply to 1898541
    TI__Mastermind 36756 points
    Hi AQ,

    20V is only possible over a Type-C connection. This is due to the fact that USB PD (Power Delivery) used the configuration channels (CC lines) to communicate with the connected USB PD device. When using a standard 4 pin USB connection, you are limited to a maximum of 5V at 500mA.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Expert 1105 points

    Hi Eric, 

    I thought that power communication is carried over Vbus. I guess you would need CC for cable detection. Is that correct assumption? 

    So how would we know if a USB3.0 port on a PC is PD enabled?

    Thanks, 

    AQ

  • 0 in reply to 1898541
    TI__Mastermind 36756 points
    Hi AQ,

    power communication in USB PD Spec is carried over the CC lines. You could read more about the USB PD Spec from the following link: www.usb.org/.../

    A standard USB Type-A port will not be PD enabled. Regardless if it is USB 2.0 or USB 3.0.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Expert 1105 points

    Thanks Eric for a reply.

    I have been reading about Type-C and USB-PD now.

    Going back now to my question, can I use TPS65983B for my application?

    I am assuming I would have a custom cable now with CC, D+/- and VBus/Gnd. I assume that I don't need to connect SBU.

    This should give me 20V/5A when connected to USB Type-C DFP and normal 5V/500mA when connected to the standard Type-A USB port.

    Thanks,

    AQ

  • 0 in reply to 1898541
    TI__Mastermind 36756 points
    Hi AQ,

    I would recommend using the TPS65982 for this application. If you want your device to be USB compliant, you will have to use a standard Type-C connection as custom cables are not permitted by USB-IF.
    If you want to support alternate modes like DisplayPort or Thunderbolt, you would need to connect the SBU lines. If not, then you can leave them disconnected. Will you be using USB 3.0 speeds as well or just USB 2.0?
    If you want to use USB 3.0, you will need to add a super speed USB 3.0 mux on your system for Muxing the super speed lines that go through the Type-C port. For USB 2.0, the TPS65982 has internal muxing for the cable flip. However, depending on the length of your cable, you may want to add a re-driver for the USB2.0 lines.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Expert 1105 points

    Thanks Eric for your reply. 

    So to answer few of your questions:

    1. We do not need to be USB compliant.

    2. We do not need Thunderbolt and DisplayPort.

    3. We would only be using USB2.0 speed.

    I am trying to go through the datasheet for both TPS65983B and TPS65982. I am trying to figure out the differences. So far, all i can tell is that TPS65983B is PD3.0 compliant.

    If possible, would you be able to summarize any other differences?

    So now you have a better idea of my device. Would you be able to tell if TPS65982 would suit my application?

    Thanks,

    AQ

  • 0 in reply to 1898541
    TI__Mastermind 36756 points
    Hi AQ,

    If you do not need to use PD3.0 functions, I would recommend the TPS65982 as it is slightly cheaper. The 83 has more RAM memory to allow for the added functionality included with PD3.0. Other than that, the functionality is the same.
    The TPS65982 would suit your application.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Expert 1105 points
    Perfect.
    Thanks Eric for walking me through it. Appreciate it. I have ordered the evaluation board. Would see how it goes.
    Thanks again,
    AQ
  • 0 in reply to Eric Beljaars
    Expert 1105 points
    Eric,
    One more question.
    Would i need a separate USB2.0 controller to talk to the PC or the USB2.0 controller is built within this device?

    Thanks,
    AQ
  • 0 in reply to 1898541
    TI__Mastermind 36756 points
    Hi AQ,

    The TPS65982 has a built in MUX to handle the cable flip on the Type-C connector. However, depending on the length of the cable or PCB trace, you may want to add a redriver on the D+/D- lines to maintain signal integrity.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Expert 1105 points

    Eric, 

    Thanks for the reply.

    My question was about the controller. Do i need a USB2.0 controller to drive TPS65982?

    Thanks, 

    AQ

  • 0 in reply to 1898541
    TI__Mastermind 36756 points
    Hi AQ,

    The TPS65982 will only MUX the D+/D- lines for cable flip on the Type-C Connector. The TPS65982 will also check the D+/D- lines for BC1.2 detection which is a battery charging protocol communicated on the USB2.0 lines.
    The D+/D- lines can then be routed out of the TPS65982 to your host processor for the USB2.0 data.

    Thank you,
    Eric