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TPS25750EVM: Help with understanding the schematics

Part Number: TPS25750EVM
Other Parts Discussed in Thread: BQ25731, USB-PD-CHG-EVM-01, , BQ25792, TPS25750, BQ25731EVM

Hello, I am using  tps25750S and bq25731 chips to try and create a pcb with usb-c power out capabilities. 
Using Altium I have wired up the tps25750s chip and based the design off the USB-PD-CHG-EVM-01 Unfortunately this device uses a different bq chip that seems to Vary by quite a bit.
The TPS25750EVM uses the bq25731 so I wanted to know if there were cad/altium files available for this device as it would greatly increase my understanding of how to wire the systems. if not are there any suggested documents to look through to get the two chips connected and working? The plan is to currently use the schematics in the tps25750EVM datasheet, but they are not that easy to follow.

Additionally, I have a question about if we wired the tps25750s correctly. 




does pin 19 (vsys) connect to A1,b1,d1 and e1, which are also connected to the output of the bq chip? where as a2,b2,d2,e2 go to pins 26 and 27 as well as the usb-c itself. 

  • Additionally we are adding these two chips just to power another pcb through usb-c. There will be no battery that is used, The device will always be plugged into a power source and no charging of our device is required. I know the bq25731 is overpowered for our use case, but its the only chip we see in stock. 
    the schematic of the BQ25792 is much easier to understand. Is there a way to wire the 31 similarly to the 92? OR are there components that we do not need to wire on to the bq25731 if the only purpose is to source power to another device without being attached to a battery/requiring the ability to charge? 

  • I was able to find an altium file for the device, it helps, but is still quite confusing haha, I wanted to add a bit more info to my last question about removing some of the connections.
    We have either 24v or 12v going to the bq chip and will be needing 9v and maybe 12v out through the usb-c to power the external device. If you have any advice of how to proceed that would be greatly appreciated. Thank you. 

  • Hi Rowan,

    Thanks for reaching out on E2E!

    I am glad you were able to find the Altium files for this device!

    Regarding the PD controller, I recommend getting started with the TPS25750 GUI which can be found below along with the users guide for it.

    GUI: https://dev.ti.com/gallery/info/1769824/TPS25750_Application_Customization_Tool 

    The GUI user guide can be found in the application under the documents tab: 

      

    You can use this tool to create usable configuration images for TPS25750S. 

    Regarding the BQ chip, I am not an expert on this device, so I will go ahead and reassign this thread to the relevant organization.

    I hope this helped!

    Thank you,

    Kevin

  • Hi Kevin thanks for the answer, Unfortunately im currently looking for advice more along the lines of hardware pcb setup. 
    It looks like the gui is only for flashing code to already setup tps system.
    I also got an email saying someone replied to the thread asking for more information about what i need from the bq chip, but i dont see any additional answers here. So ill restate some of what im looking for and hopefully they can see it?

    For the TPS25750S I mostly just want to know if pin 19 (vsys) connects to A1,b1,d1 and e1 of the mosfet, which also connects to the output of the bq25731 chip? this may be more of a question for the bq expert. but everything else for the tps25750S is goinng well for me.

    For the BQ25731 - I need my device to provide usb-c Power out. The power out will be used to power a different pcb which i did not design. This device requires 9v or 12v through usb-c (around 20W) from what i understand in order to have a functioning usb-c PD source I need a tps25750 (for communication) and a bq chip (for altering the voltage). My system does not have a battery as it is plugged in at all times. I have tested the USB-PD-CHG-EVM-01 and it works out of the box for my application. Unfortunately the BQ25792 is out of stock so I will have to use the BQ25731 which I am told will work. 
    The main issue is the BQ25731 is much more advance and has a much more complex schematic. Is there any pins or components that I do not need since my system does not have a battery? The BQ25792 makes sense to me through the schematic and I could add it to the device no problem, The BQ25731 has so many components it requires and seems like all the components will be much harder to get correct and will take up more space. So the main questions are: can i remove components/pins in the BQ25731 since there is no battery being charged, just voltage that needs to be decreased for the usb-c power system, OR are there any other replacement BQ chips that are simpler that would allow the tps25750 to properly provide usb-c output power that would be in stock at a distributor?  
    Thanks


  • Regarding the BQ25731 schematic, please check it out BQ25731EVM user guide. https://www.ti.com/tool/BQ25731EVM

    It is similar to BQ25792 but more powerful.