TPS65987DJEVM: Waveform observations

Ernest Yong

Part Number: TPS65987DJEVM

Hi all,

I had a slight confusing after testing the waveform from the TPS65987DJEVM. I configured the EVM as a 20V source and connected my laptop(Sink) to observe the waveform.

Please take a look at my captured waveform and I appreciate it if you could help me with the following questions:

1) Why is there voltage at my CC1 before connecting my type C cable to the laptop ?

2) As shown in the red arrows (Highlighted area) of the screenshot, why does my CC1 and CC2 behave this way?

Thank you in advance for your help!

over 2 years ago

+1 Chuck Branch over 2 years ago

TI__Mastermind 26880 points

Ernest,

If you have the TPS65987DJEVM configured to be a source, then it will pull the CC lines up to 3.3V with a resistor to present the Rp that is necessary to detect connections with the Rd presented by the source.

In your capture, CC2 is used to provide VCONN at 5V and CC1 is used for the PD modem. The signaling that you are seeing is PD transactions related to determining the port function after power is negotiated.

Regrads,

Chuck

0 Ernest Yong over 2 years ago in reply to Chuck Branch

TI__Expert 4315 points

Thank you !

0 Chuck Branch over 2 years ago in reply to Ernest Yong

TI__Mastermind 26880 points

happyto help

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TPS65987DJEVM: Waveform observations