TPD6S300: About reducing VCONN voltage

Hello,

Regarding to VCONN on TPD6S300, my customer is asking some question.

They will design TPS65987＋TPD6S300 as USB type.C interface.

 (Question)

They estimate VCONN voltage as following.

･5-300mA×(222mΩtyp＋278mΩtyp）＝4.85V(typ)

･5-300mA×(325mΩmax＋415mΩmax）＝4.778V(min)

TPS65987: 222mΩtyp（325mΩmax）

TPD6S300: 278mΩtyp（415mΩmax）

Above voltage are matched Thunderbolt3 VCONN voltage standard.(4.75-5.5V)

But they have a concern of reducing voltage by power supply (5V) variation or loading 3A on VBUS.

In this case, should they need to provide external power supply(5V) to avoid reducing voltage?

(The external power supply will be placed close to TPS65987/TPD6S300.)

They will reduce voltage drop except Ron(on resistance) of TPS65987/TPD6S300.

Could you please give me advice or comment?

Regards,

Tao2199