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TPS25859Q1EVM-161: How fast charging mode is selected as per BC1.2?

Abhishek Chari
Prodigy 20 points
Part Number: TPS25859Q1EVM-161

Tool/software:

We have designed a dual Type C USB charger using the reference module TPS25859Q1EVM-161 for one of our customers. We want the fast charging to work but the customer says the fast charging is not working. I have few questions regarding this particular chip as mentioned below.

1. Does this IC support BC1.2 specs?

2. The datasheet says the IC can advertise 1.5A and 3A charging capability on CC lines but how is it selected?

3. How to select the fast charging or is it selected on its own through CC lines when the USB Peripheral is connected? 

4. Do I need any additional circuitry apart from this chip for fast charging?

5. The customer is trying to fast charge tablet/ipad, does this chip with 15W output support tablet/ipad fast charging or only mobile phones can be fast charged? 

  • 0
    TI__Mastermind 32791 points

    1.  The TPS25859Q1 does not support BC1.2.  The TPS25858Q1 supports BC1.2 DCP, shorted mode, 1.2V-mode (not BC1.2), and Divider 3 mode (not BC1.2)

    2.  Both the TPS25859Q1 and TPS25858Q1 will always advertise 3A, it is built into the IC.  The actual current limit provided by the device will be set by the ILIM pin resistor described by the RILIM value in the datasheet.  

    3.  The device will advertise on both the CC lines as well as the USB pins for the TPS25858Q1, but the actual current available is set by RILIM

    4.  No

    5.  The phone or IPAD will decide if the offered current is sufficient, so the TPS25858/9Q1 cannot guarantee that they will change, just that they will be offered 15W.

    Regards,

    Chuck

  • 0 in reply to Chuck Branch
    Prodigy 20 points

    Thank you for your response, I will check with the customer and get back to you.

  • 0 in reply to Abhishek Chari
    TI__Mastermind 46461 points

    Hi Abhishek,

    Sounds good. Let us know.

    BR,

    Seong

  • 0 in reply to Chuck Branch
    Prodigy 20 points

    The issue still persists, customer used Samsung and iPhone mobile phones to test the circuit and it is only drawing 0.8A of current for charging. I have attached the schematic PDF of the circuit.

    1. Could you please check and let us know if there are any mistakes in the circuit which is not allowing higher current for charging or do you have any idea what could be going wrong?

    2. Does Samsung and iPhone fast charging works in a different manner for which we might need a different type of IC? Kindly provide us with some inputs since we need to get this right somehow.

    3. We had set output voltage to 5.17V and output current limit to 3.55A.

    4. Another problem we see is TS pin voltage, do you feel that could be one of the reason output current is reducing? The MPN we used for 470k NTC thermistor RT1 in our circuit is NCP18WM474E03RB. Is our resistor values correct as per the temperature values written in our circuit?

    Thanking you in anticipation. Your help will be greatly appreciated.

    TPS25859 circuit.pdf

  • 0 in reply to Abhishek Chari
    TI__Mastermind 32791 points

    Abhishek,

    1. Here are the BOM updates that I recommend you check that the DNI spec is followed

        a.  Ensure that R75, R76, R89, and R90 are not installed.

        b.  Ensure thatR52, R53, R56, R58, R60m R64, R61, and R65 are not installed 

    2. They have options on how the handle fast charging.  The TPS25859QRPQRQ1 offers the proper charging for type C 3A. (15W)  It is up to the phone how it charges based on what is offered. I need a scope capture of CC1/CC2 on each port in order to see what is being negotiated in the type C to see if the phone is being offered the correct voltage.

    3.  This setting looks correct to me

    4.  Have you checked the voltage of the TS pin during operation?  Section 10.3.11 of the datasheet describes the calculation that is necessary to set the voltage on TS.

    In order help with debug, I would like to have a 4 channel scope catpture with CC1, CC2, VBUS, and TS.  This will allow me to help understand what is happening in the system.

    Regards,

    Chuck

    .