Other Parts Discussed in Thread: TPS65982, TPS65982-EVM
Hello. We are testing the use of 2 x TPS65982 EVMs + Lecroy PD Bus analyzer to observe the packets to/from each EVM.
The EVMs are factory default configured with ID #2 (as shipped from the factory).
If we apply an external 19 VDC power supply to one EVM, the opposite EVM will power up as it should and vice versa. The HV LED is enabled as it should since the power supply (VBUS) is 12-20 volts.
The question is why we are seeing 12 volts being passed from one EVM to the other. The interconnect cables are passive, non-emarked cables so we do expect the voltage rail to be limited to 12 volts or under but confused on how the 12 volts was generated.
Are we correct in that since the interconnect cables are not emarked, the TI PD controller limited the voltage to 12 volts @ 3A ? We will study the EVM schematic and related material but will appreciate comments on this subject.
Likewise, is this scheme flexible in that if we announce / advertise say xx volts, will the TI PD controller dial up this xx voltage from our 19 volt external source ? Or is this fixed to 12 volts only ?
To date, we thought that what is an external fixed power supply will be forwarded as-is to the mating UFP device if the cable permits this power / current pass-through. Respectively, for this specific case, we expected the remote EVM to NOT have any voltage present on VBUS since the cables are not emarked.
