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TIDA-03027: Questions about TIDA-03027

Part Number: TIDA-03027

Hi All

The reference design ITDA-03027 is very helpful. After reading it, we some questions about it:

1.The first TPS65983B (U17) ,which is connected with Type-C plug, can only be used as source. The current direction is only from PP_EXT to UFP_VBUS, isn't it?

   That means it can only be used to charge laptop, but can not be charged by laptop. Am i right?

2. The second TPS65983B (U2), which is connected with Type-C receptacle, can only be used as sink. The current direction is only from DFP_VBUS to D_PP_EXT.

    That means it can only be used to be charged by external USB type-C power adapter. AM i right、

3. Based on the above thoughts, we wondered how this mulitport adaper could be powered by laptop without external power adapter.

    The only power path is DFP_VBUD -->D_PP_EXT-->SYS_PWR-->PP_EXT-->UFP_VBUS.

   The reason is:

    For TPS65983B (U17), the voltage on current sense pin SENSEP shoud be larger than pin SENSEN, shouldn't it? Otherwise the reverse current proection does work.

    That means the current direction is only from SENSEP to SENSEN, doesn't it?

    If we remove R35 (connecting SENSEP and SENSEN to PP_EXT), this TPS65983B (U17) can be used as source or sink based on CC communication. Am i right?

4. On sheet6, SYS_PWR -->PP_EXT

     Using LM3489 as voltage converter, and using VSEL_9V/VSEL_15V/VSEL_20V to control the voltage to PP_EXT.

     Why do we need to control PP_EXT voltage via VSEL pins? USB type-C PD protocal should use CC pin to communication and negotiate voltage, should it?

We really apppreciate your support and help.

thanks

best regards

 

  • Hi Haiping,

    1. U17 can be used to Source or Sink. The default config allows it to source 5V, 9V, 15V, or 20V through the Type-C plug. With the default config, you can also choose to Sink 5V.

    2. The second 83B (U2) can be used to Sink 5V, 15V, or 20V with the default config. It can also be used to Source 5V.

    3. The 83B (U17) will Sink 5V through the internal 5V path on the device. It will then use the internal OCP circuitry for current detection.

    4. You are correct, the voltage will be negotiated by the CC lines. However, the DC-DC converter on the board must also be aware of the voltage negotiated by the PD controllers. We use the GPIOs on the 83B to control the feedback resistance of the DC-DC converter to adjust the output voltage to what was negotiated by the PD Controller.

    Thank you,
    Eric