Original question:
Tool/software:
Dear TI Support,
I need to use 2 TPS25751 togheter in the same board, each one of them connected to it's own Type C connector.
The user can plug an PD adapter in one of the connector and a Type C Load in to the other (Each connector can be source or sink, the role is not defined).
I need 20V 5A for my circuit, The sink negotiate the voltage correctly but the source seems to deliver only 5V (even if PPHV is 20V).
Do you have some suggestion to give me?
Thanks
Hi Chris,
thank you for your fast reply, I tested the two part separately and they work fine as sink, as source work only in 5V output.
Unfortunately I cann't give you a log file because I don't have PD analyzer yet, it will arrive me next week.
I give you the schematic and the json file. The device is configured in safe mode.
Thanks you very much.
Stefano
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Hi Stefano,
Can you draw a block diagram of what you are expecting? I need to better understand your system. Your schematic only shows on PD controller and a HV -> 5V buck.
How are you supplying the higher voltages?
Issue #1 is that your config is only set to source 5-V. If you look at the configuration you selected, you only have the 5-V internal path selected for source, and only have the high voltage external path selected for sink.
Thanks and Regards,
Chris
Hi Chris,
Attached you can find the block diagrm of the system which is composed by two block that I posted before.
The two board of the system shares the PPHV and the ground, The first system is powered by an adapter and I can plug more system one to the other.
I selected the last configuration because I don't have a battery charger IC and I don't know how to choose a different source.
Thank you very much
Kind regards
Stefano
Hi Chris,
I checked 20V at PPHV node, 3.3V at VIN3V3 and 5V at PP5V as you suggested and they were ok.
I tried to select in the transmit source capability only 5V 3A and it worked correctly.
I tried to add 15V 3A (supplying 15 V on PPHV with an Power supply) and it seems to reset every time there is a negotiation.
Meanwhile the analyzer is arrived, attached you can find the trace:
Can you tell me how can I be sure that the system is not in deadbattery? The only thing I checked are the voltage (3.3V, 5V and 15V in this last case).
I removed the initiate swap to sink but I didn't see any changes.
Than you very much
Stefano
Hi Stefano,
There is a Dead battery flag field in the boot flags register.
Thanks for the logs, it looks like we are missing the "PS_RDY" message that should come after the Accept message. After the Source side accepts the requested power contract, it needs to transition the output voltage, and then will send the "PS_RDY" after the power contract is ready. The TPS25751 might not be sending it because we are expecting to see 15-V (or 20-V in the 20-V case) on VBUS.
Can you check the Gate_VSYS and Gate_VBUS signals to see if they are asserting properly? It seems like the voltage on PPHV is not passing to VBUS and this is causing the failure.
Thanks and Regards,
Chris