TPS25751EVM: Sourcing Device Implementation

Francisco Pastorini

Part Number: TPS25751EVM
Other Parts Discussed in Thread: TPS25751

Tool/software:

Hello and thank you in advance

We are trying to implement a system that works as a Sourcing device. The system should be able to charge a Samsung Tablet while still working as UFP (the tablet should host the communication while beeing charged by our system). For this purpose we got TPS25751EVM to see if we can integrate it in our system

We are having some issues and we need support from TI to see what is happening.

First of all we are having issue flashing the board with the GUI, we recieve this message constantly. We belive it is because the TPS25751 is not recieveing P3V3 correctly, we could not find in the board The supposed LDO U11 that powers this line but we belive that is not working.

We removed J13 and provided 3V3 to VIN_3V3 externally and we got to flash the device from some computers, in others the same error flashing device notification pops up when reaching to 70%. We saw that other users had the same problem so altough this is an issue for us we are ignoring it for the moment.

After succesfully flashing the device we connected the tablet to the EVM and it looks like it is charging correctly but the EVM does not provide any way to check that communication role it is also configured as desired as the data lines are literally stubs in the default configuration with R32 and R33 not mounted. Do you have any recommendation on how to test this? We were planning to solder some cables to the data lines and take them into another system but we would like to avoid this type of reworks if possible

Thank you in advance
Best regards
Francisco

7 months ago

0 Chris Sterzik 7 months ago

TI__Guru 64001 points

Hello,

If you have a PD analyzer, then you can see what is advertised and data role. I you have an I2C tool, then you could read the status from the device.

https://www.ti.com/lit/ug/slvucr8a/slvucr8a.pdf#page=28

Regards,

Chris

0 Francisco Pastorini 7 months ago in reply to Chris Sterzik

Prodigy 130 points

Hello Chris, Hope that you are doing well?

Thank you for your answer. We have been playing around a little bit reading the registers using a I2C tool. Unforunately we do not have a PD analyzer

Reading the status register we have seen that the device is configured as UFP and Source just as we need but are not beeing able to archieve data transmition between our PCB and the Tablet

We are connecting our system to the VBUS, GND, CC1 and CC2 testpads of the DK, the datalines D+ and D- goes to a CP2102N-A02-GQFN28R.
We are also connecting 24V to the VSYS testpad, LDO_1V5 and LDO_3V3 are turn on deliverying the expected voltage so I guess the TPS257 is working fine.

0 Ghouse Mohiuddin23 7 months ago in reply to Francisco Pastorini

TI__Expert 8050 points

TI US was closed today, sorry about delays in response.

0 Chris Sterzik 7 months ago in reply to Francisco Pastorini

TI__Guru 64001 points

Hello Francisco,

Please take a look at the SBU lines. Does the presentation of LDO_3V3 on the SBU line cause the Tablet to not send data?

https://www.ti.com/lit/ug/slvucp9a/slvucp9a.pdf#page=37

Regards,
Chris

0 Francisco Pastorini 6 months ago in reply to Chris Sterzik

Prodigy 130 points

Hello Chris, thank you again for your help.

Im sorry for my delayed response we found out that both LDOs in the board got burned together with the MCU and that was causing a malfunction, we got another one DK and we were able to configure the device as a sourcing device with no issues.

We are now having another issue that is that our tablet is charging at a very low current, we are not beeing able to drive more than 5W from the controller. The voltage on the CC connected line is 1.8V approximately so I guess that the controller is pulling the CC line up with a 10k resistor. When we connect the tablet to a charger (USB A to USB C) we get almost 12W of power that that is what we are aiming for.

0 Chris Sterzik 6 months ago in reply to Francisco Pastorini

TI__Guru 64001 points

Hello,

Francisco Pastorini said:
The voltage on the CC connected line is 1.8V approximately so I guess that the controller is pulling the CC line up with a 10k resistor.

It is a current source and with the Rd of the tablet of ~5K, the tablet should recognize the current available. Do you know if the tablet will only draw larger currents if BC1.2 is available or some other criteria?

Regards,

Chris

0 Francisco Pastorini 6 months ago in reply to Chris Sterzik

Prodigy 130 points

That is a good question that I unfortunately don’t have the answer to. The tablet is a Samsung SM-X210; maybe you have already heard of a similar application for that device.

If we need to implement battery charging, does that mean we would lose control of the data bus?

The tablet also needs to communicate with an MCU inside the tablet so we cant lose that comm bus

0 Chris Sterzik 6 months ago in reply to Francisco Pastorini

TI__Guru 64001 points

Hello,

In discussing with my colleague there are known compatibility issues with Samsung phones, so i would conclude the same with the tablet. The issue is that the sink is expecting something beyond the Type-C and PD specification before requesting higher power. if this is not received then only a lower power contract is allowed. At this time we do not know what is required or expected from the Samsung products.

Regards,

Chris

0 Francisco Pastorini 6 months ago in reply to Chris Sterzik

Prodigy 130 points

Thank you Chris, hope that you are doing well

We have been testing on different tablets and phones these past few days, and we are experiencing the same issue on all of them. We are unable to charge beyond 5W, even though our system is capable of delivering much more. Could the BC1.2 interface solve this issue? Do you have any knowledge about this?

Additionally, you haven’t answered my question about losing control of the data bus when using Battery Charging.

Thank you!

0 Chris Sterzik 6 months ago in reply to Francisco Pastorini

TI__Guru 64001 points

Hello,

Francisco Pastorini said:
Could the BC1.2 interface solve this issue? Do you have any knowledge about this?

Yes, if the tablets being tested do not support PD but rely upon BC1.2, then this would address the issue.

Francisco Pastorini said:
Additionally, you haven’t answered my question about losing control of the data bus when using Battery Charging.

The TPS25751 supports BC1.2 CDP (Charging Downstream Port), which allows for battery charging and data. I have not been able to find any examples of using BC1.2 CDP to achieve higher power delivery (and maintain data), but i will keep looking.

https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1134977/can-i-use-usb-bc-1-2-charging-and-data-communication-with-mobile-device-simultaneously

Regards,

Chris

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TPS25751EVM: Sourcing Device Implementation