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TPS65987D: Connecting VBUS1 and VBUS2

Part Number: TPS65987D

Hi, 

The datasheet mentions that the VBUS1 and VBUS2 pins should be tied together. If the HV_PP2 is connected to GND and the application is only using HV_PP1, why cannot the VBUS2 pin be grounded? 

Thank you,
Ishraq

  • Hello Ishraq,

    During boot up, the internal ADC's measure the level of both VBUS1 and VBUS2, so grounding one could cause issues for your end application. Even though you are not using the second power path, still connect VBUS2 to VBUS1 so that the device can boot without issue. Hope this helps answer your question.

  • Hi Adam,

    If PP_HV2 is connected to GND, wouldn't that short VBUS to GND? What is stopping that from happening?

    Also, the schematic (figure 33) on page 44 of the datasheet shows VBUS2 and HV_PP2 both connected to ground. I noticed the revision history changed pin description to better clarify that VBUS1 and VBUS2 should be tied together. Should the schematic be updated?

    Thank you,
    Ishraq

  • Hello Ishraq,

    No that will not occur as the internal power path connecting VBUS to PPHV2 would never close since you will configure the device to only act as a source or sink, not both, and will only be using the power path connecting VBUS to PPHV1

    That needs to be updated, thanks for letting us know.