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USB Type-C – Power Negotiation Issues”

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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.

  • 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.

  • In reply to Eric Beljaars:

    Hello I haven't heard from you.
    Is the mentioned part a break out board or not?
    I need both the UFP and the DFP male and female connectors.

    I'm also wondering about micro usb OTG parts. male and female?

    What is OTG standard baseline discharge range V/A=W ?
  • In reply to Chase Weston:

    Hi Chase,

    1) Unfortunately I do not see in the white paper where is says 3V. As Eric described, USBC (even 2.0, 3.1, and BC1.2) are all 5V.
    2) If the TPS25810 is in the end equipment, the IC's min recommended input is 4.5V so yes there needs to be a regulator to have a higher voltage for the IC to operate if the main source (battery) is lower.
    3) Yes I recommend getting information from the battery charging team regarding battery information. The USBC main goal is to make sure a compliant load is connected before allowing power to the load.
    4) I would add a new thread for the battery charging team to comment on this. It may help to view their portfolio products so they can comment on a specific part number.

    1) Are you interested in Type C only (5V/15W) or interested in USB PD (power delivery)? That's correct, anything higher than 15W and different from 5V (9,15,20V) is USB Power Delivery in which we would not recommend TPS25810 and recommend TPS65987D instead.

    Micro USB have different connectors for USB2.0 and 3.0 and are lower power than Type C if you need the 15W. I recommend sticking with the Type C (TPS25810) if power delivery is not a requirement. For micro USB USB2.0 supports only 2.5W while 3.1 supports 4.5W.

    The TPS25810 is a DFP controller. Its board uses a female connector. Please see below link for its schematic and board image.

    For OTG, Note the TPS25810 cannot reverse roles. If you're looking for dual roles, you need to look at the TPS65987D.

  • In reply to Darwin Fernandez:

    Thanks for response.

    Recap on the POC Adapter. The adapter gets all its power from any random via phone, tablet, computer, wall charger with a USB-C connector.

    I need to ultimately produce 9-10Watts, 3.5 v-4 volt range. Amps will vary I assume to meet target watts. The ohms needed are 1.3 to 1.4 R.

    I don't need PD, because I am at 10Watts at most.

    The adapter will plug into the Samsung S8 USB-C female port, or any other power device and receive power.

    The Adapter's USB-C connector with the appropriate chip should just tell the Host in this case the Samsung S8 to send the 5V 3A if it can, and then the circuit inside the adapter will step down or adjust the  V/A to meet the appropriate 9-10Watts, the 9 to 10 watts will then satisfy the 1.3R need of the slave device.

    Response to you.

    1) I think the 3V is just a mistake. Was probably referring to 3A.

    2) Confused on DFP or UFP? I believe I need the UFP for the adapter side, The DFP is in whichever Host/power device I am plugging into. Correct?

    I am not building a Host power supply, I am building a slave receiver device that will convert the V/A to the correct use level.

    You refered me to the DFP but I believe htis is fo the host device, or is it dual role.

    I just need the host to send the power.

    3) I will look at info from BCT

    4) Will add a new thread to battery charging team (BCT).

    1) to answer your question I only need USB-C 5v/15w Not PD.only need 9-10Watts.

    I will stick with the USC-C for now, and in the future, I will switch over to solving the USB-MIcro OTG possibilities.

    That will be a whole other issue of upping V-A inside the adapter, since the possible outputs are either 2.5-4.5W.

    Although,  it would be nice to know which USB Micro female and male breakout board connectors would be appropriate for OTG power consumption.

    Further questions

    A) The power source Host should have the DFP, Is this correct???

    That would mean I need need the UFP, that would either be a Male USC-C connector,,OR I could connect a USB-C UFP Female connector to a power cable to Connect the Host/power to the Adapter.

    B) Do you have the USB connectors as breakout boards?

    I am not seeing any pictures for the actual connector only the chip, having a breakout board would really help for building the POC.


  • In reply to Chase Weston:

    Hi Chase,

    A) Yes since you're not looking for a dual role solution. The host will send data (DFP) and source VBUS.
    B) Unfortunately we do not have breakout boards for USB connectors. We typically just use USBC female connectors on our EVMs.


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