USB Type-C – Power Negotiation Issues”

USB Type-C – Power Negotiation Issues

Hello this is my first thread here.

At this time I am developing a Proof of Concept (POC) that is an adapter for Type-C devices..

I need direction on which PARTS: connectors and resisters I would need to complete the build.

I am taking a preexisting device that uses a designated 3.7V 550mAH LIon battery for power.

I want to cut the wires and create an adapter, so I can use alternative power sources via USB Type-C connectors.

The first Goal is that the  adapter will receive power from a Samsung S8 mobile device.

Device Specs:

10W to power 1.3 R.

3.7V and 550 mAH LIon battery existing power source; to be removed.

The device should receive 3.5V to 3.8V range and can not receive more than 4V.

I am unsure of the Battery Discharge /Pulse Amp rating? But I am working on it.

1)  Can an USB-C connector control a variable Voltage under 5V or is it only preset voltages 3V or 5V?

I read the paper that mentioned 3V and 5V, with max of 15W=5V x 3A, before having to switch to PD, but it didn't elaborate on if something like 3.6V is possible from the Host.

I guess, If the phone sends 5V I could put the correct resistor in there to step it down if needed.

2) Which correct Type-C connector, Part ,chip resister do I need to negotiate with the phone or any other Type-C device to deliver 10W? 

I am unsure at this time what the Discharge/Pulse Amps are for a Samsung S8 Lion poly phone battery or any other for that manner.

I have heard that it has provided 7.5W to power a peripheral device, but that was all that was demanded. don;t know if that's a max or not.

If I have to put an inductor, booster, or capacitor in the adapter I guess I will.

3) Is 10 Watts, 10 Watts no matter how you slice it?       e.g 5V x 2A=!0W or 3.5V x 2.69A=10W.

Just wondering if it would fry the circuit?

That's it for now, I appreciate any help I can get.

Getting the correct chip connector setup is critical. Thanks.

6 Replies

  • Hi Chase,

    1. Per the USB Type-C Specification, 5V must be presented initially on the Type-C connection. After a Type-C implicit contract is established, USB PD negotiations may begin.

    2. I would recommend purchasing some of our EVMs and seeing which one would meet your needs. You can refer to the TPS25810 if only 10W is needed.

    3. The minimum USB Type-C voltage is 5V. So 10W on an implicit Type-C contract would be 5V @ 2A. for a PD contract, however, it could be 10V @ 1A.

    If this answers your question, PLEASE select This resolved my issue

    Thank you,

  • In reply to Eric Beljaars:

    thank you for responce.

    1) I read the paper "A primer on USB type-c and power delivery applications and requirements"

    It stated, that it was either 3 volts or 5 volts without PD and that PD is established after 15 watts .

    Is this correct?

    2) I will purchase the TPS 25810 connectors.

    Am I right in assuming, that the 5v and Amp output on the phone is assisted with a booster and/ orinductor, since the outputs exceed the 3.5V 3000mah battery on the S8 Samsung?

    3) Should I post a separate thread regarding Lion poly battery mAH rating vs discharge-pulse output?

    I'm just having trouble understanding how a battery can push out more Amps than the overall mAH rating.
    The numbers just don't seem to make sense to me as far as overall value of mAH vs discharge Amp.

    4) Would the 5-volt be too much or is that something I should just step down once it's in the adapter to my targeted voltage?
    Should I be more concerned with the voltage or with the overall Watts?

  • In reply to Eric Beljaars:

    thank you for the reply..

    I will use the recommended connector.

    My understanding is that power delivery is engaged after 15 watts.
    Is this correct?

    2) Am I correct in assuming that the phone has a booster or inductor to deliver more Voltage and Amps than is rated for the 3.7 volt 3000mah battery?

    3) Should I post a separate thread regarding battery mAH vs discharge ratings and output?

    Or is there a paper or link you can provide?

    I'm having trouble making sense of the numbers, overall mAH battery rating as opposed to discharge pulse amps.

    The existing battery on the device that I am going to get rid of is a 3.7V 500 mAH, yet it's still delivering 10watts, assuming it is due to the discharge or pulse amps that are capable from the battery.
  • In reply to Eric Beljaars:

    Please let me know if you are receiving my replies I do not see them posted on the thread
  • In reply to Eric Beljaars:

    I will purchase the suggested part.

    1)Am I correct in assuming power delivery in gauges after 15 watts.
    Therefore I don't need to concern myself with power delivery since I'm only needing 10watts.

    2)Am I correct in assuming that the phone has a booster or inductor to provide more volts and amps than is rated for the 3.7 volt 3000 mAh Samsung battery?

    3)Should I post on another thread any issues regarding mAH vs discharge pulse ratings?

    The numbers don't make sense I don't understand how the exist device battery 3.7 500mah can provide 10watts my assumption is that the discharge amps are higher than mAH value.
  • In reply to Chase Weston:

    I am wondering if you can tell me what part would be best for me if I went with a micro USB as well.