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TPS25750EVM: Self Power Design?

Don Pitchford
Intellectual 255 points
Part Number: TPS25750EVM
Other Parts Discussed in Thread: TPS25750, TPS25751, TPS25751EVM, TPS552872EVM, TPS22976, BQ25798

Tool/software:

Reviewing the TPS25750EVM (schematic attached)

1.  This doesn't appear to be self power over the USB-C.    Is that correct?   It seems you need barrel connector.   I have the board on order, but, not sure if it will fit my need.  
2.  If it can't be self power, do you have a reference design that shows self power.   This design has all the aspects I need (BQ, 12V, USB-C).  

Thanks


Don


3718.PSIL138A(001)_Sch.PDF

  • 0
    TI__Mastermind 37855 points

    Hi Don,

    For any new designs, please use the TPS25751, it is the P2P feature compatible successor to the TPS25750. The TPS25750 is NRND.

    I will answer the following questions in regards to the TPS25751

    Don Pitchford said:
    1.  This doesn't appear to be self power over the USB-C.    Is that correct?   It seems you need barrel connector.   I have the board on order, but, not sure if it will fit my need.  

    The TPS25751 is capable of "self power over the USB-C" and supports "dead battery mode", where it can boot and be powered from the type-c port. Search "dead battery" in the datasheet for more info.

    Don Pitchford said:
    2.  If it can't be self power, do you have a reference design that shows self power.   This design has all the aspects I need (BQ, 12V, USB-C).  

    It can be self powered.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    Intellectual 255 points

    Thank you kindly for your reply.   I did received my USB-PD_CHG-EVM evaluation board.   It seems to be spot on with my design for most part and I like it because it is self contain:

    I looked at the TPS25751EVM on Digikey, it is listed as "no longer manufactured".    But if the TPS25750 is NRND, do you know what this means.  Would I have 3 year life?    

    Do you know what would be equivalent of the USB-PD-CHG-EVM board for something that is current.  (USB C PD with BQ battery charger (4 cell Li-Ion).

    Thanks again.    

  • 0 in reply to Don Pitchford
    TI__Mastermind 37855 points

    Hi Don,

    We do not recommend the TPS25750 for any new designs. The USB-PD CHG_EVM was updated in line with the TPS25750 NRND to be using the TPS25751. We are currently working on updating the documentation, but the CHG-EVMs at ti.com should have the TPS25751 populated instead of the 750.

    If you have the soldering capabilities, you may be able to swap the IC on your current CHG-EVM from the TPS25750 to the TPS25751.

    I'm not sure why the TPS25751 says obsolete on Digikey, it is still supported and in stock on TI.com.

    The TPS25751 is an active part, I would not recommend using the TPS25750.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    Intellectual 255 points

    Chris,

    Message received.  I will move to TPS25751.     I currently have the USB-PD-CHG-EVM working with TPS552872EVM with 4 cell li-ion batteries and performing as expected.    Running it through the paces and current very happy.  


    1)  The TPS25751 is pin for pin compatible with TPS25750, so it a matter of swapping it out.   I want to duplicate the USB-PD-CHG-EVM board, but will swap out TPS25750 with the 71 and load new eeprom firmware.   Anything else I have to worry about? 

    2)  I am worried about battery drainage on the USB-PD-CHG-EVM when I turn off the load (SYS), disconnect the USB-C,  what type of drainage should I expect on my battery pack?    Something I can measure, but wondering if you know off the top of your head.

    3)  Is there an easy with to turn off SYS from BQ25798 to shut the system down, but keep ability to charge the batteries?    I was thinking of using TPS22976 to shut off SYS to the system, but not sure that is the best approach.

    Thanks again and making progress,

    Don

  • 0 in reply to Don Pitchford
    TI__Mastermind 37855 points

    Hi Don,

    Don Pitchford said:
    1)  The TPS25751 is pin for pin compatible with TPS25750, so it a matter of swapping it out.   I want to duplicate the USB-PD-CHG-EVM board, but will swap out TPS25750 with the 71 and load new eeprom firmware.   Anything else I have to worry about? 

    Good catch here. We do acutally recommend increasing the EERPOM (u5) size to 512Kbit. The patch size is currently right at the max size of the 256Kbit EEPROM, and there are some concerns it will go over.

    This picture is from the TPS25751EVM user guide and shows what part we are using there.

    Don Pitchford said:
    2)  I am worried about battery drainage on the USB-PD-CHG-EVM when I turn off the load (SYS), disconnect the USB-C,  what type of drainage should I expect on my battery pack?    Something I can measure, but wondering if you know off the top of your head.

    I'm not sure about this one, I primarily support the USB-C PD products. Could you submit another E2E thread specifically asking about this?

    For any USB-C PD related questions, you can continue to ask here.

    Don Pitchford said:
    3)  Is there an easy with to turn off SYS from BQ25798 to shut the system down, but keep ability to charge the batteries?    I was thinking of using TPS22976 to shut off SYS to the system, but not sure that is the best approach.

    Another BQ question that I'm not too sure about. It doesn't look like there is a dedicated switch for disconnecting the SYS pin from the rest of the charging path, so you might need your own way. I would confirm with the BQ team directly in the separate thread you make though.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    Intellectual 255 points

    Updated the schematic for TPS25751, added 512KB eeprom.     Couple of follow up questions:

    1 - The ADCIN1/2, In the schematic, it has it tied to LDO_1V5.    If I always want to be a sink mode,  should I change the ADCIN input 1=3.3V, 2=GND?   I added voltage divider, but not sure if this should be VCC3.3 or VCC1.5V.


    2 - I am going to run the USB-C signals to a USB Hub -  Just validating that I don't need the USB 2.0 signal to go into the TPS25751, correct?

    I do have questions on BQ25798 on support barrel connector as well as USB-C.     Do I need to open another thread to have some check if my design is correct?

    2335.output.pdf

  • 0 in reply to Don Pitchford
    TI__Mastermind 37855 points

    Hi Don,

    Don Pitchford said:
    1 - The ADCIN1/2, In the schematic, it has it tied to LDO_1V5.    If I always want to be a sink mode,  should I change the ADCIN input 1=3.3V, 2=GND?   I added voltage divider, but not sure if this should be VCC3.3 or VCC1.5V.

    Either are fine, these just define the PD controller behavior in dead battery mode (i.e. when there is no board power and the system and PD controller take power off of the Type-C connector.

    For Always Enable Sink, we close the power path and negotiate a type-c sink contract (5-V, 3-A max)

    For Safe Mode, we do not enable the sink path, but will still negotiate a type-c contract.

    Either way should work.

    On "dead battery" boot, the TPS25751 will generate it's LDO3V3 rail off of the power coming from the Type-C port. This will power the I2C EEPROM. On power up, the TPS25751 will automatically load the fw image from the EEPROM and operate in whatever config is loaded there.

    Don Pitchford said:
    2 - I am going to run the USB-C signals to a USB Hub -  Just validating that I don't need the USB 2.0 signal to go into the TPS25751, correct?

    Correct. If you want to support BC1.2, a legacy charging scheme, we have the ability to use the GPIO4/5 pins to advertise and detect that protocol. These pins do nothing else with the USB data. If not, do not connect the D+/D- pins to the TPS25751, and route the pins to whatever USB2 endpoint you have on your design. The TPS25751 does nothing with the USB2 data.

    Don Pitchford said:
    I do have questions on BQ25798 on support barrel connector as well as USB-C.     Do I need to open another thread to have some check if my design is correct?

    If you already posted another thread for the BQ25798, you can just ask this question there. That seems to be a system level question so I'm not too sure who is the best to ask. Feel free to ask it here as well and I can see if I can help.

    Thanks and Regards,

    Chris