This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

  • TI Thinks Resolved

BQ25010: can i short USB, BAT/OUT1, BAT/OUT and CE to a 6.8v battery

Prodigy 45 points

Replies: 7

Views: 200

Part Number: BQ25010

Hi, I am trying to modify an old design using bq25010.  In the old design, CE is grounded, and it use bq25010 to charge a 3.7v Li battery, as well as generate 3.3v for my board.

for my new design, I need to use a different 6.8v Ni-MH battery with an external charger.   But I do not want to change my old board design, so I will keep the bq25010.

so I have two questions:

1. I am thinking of shorting 4 pins:  USB, BAT/OUT1, BAT/OUT and CE to the new 6.8v battery, is it OK?  basically I am using bq25010  only as a buck converter to generate 3.3v for my board. 

2.  if I tie EN and CE pin permanently to 6.8v,  will it be ok?  any long term reliability issue?   the datasheet only specify absmax for EN is 7v, but didn't specify absmax for CE pin.

Please advice.

Thanks.

John

  • Hello John
    Running this close to the Absolute Max Rating long term makes me nervous. Configuring the unit as only a buck converter has not been done.
    Have you been able to run test on the unit in the proposed configuration?

    It will be early next week before I can look at this more.

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    Please click "This resolved my issue" button if this post answers your question.

    For more information on Battery Charger Solutions see Link

    Tip -- Improve search results by including "FAQ" 

  • In reply to Bill Johns:

    Hi Bill:

    Please let me know once you found out the answers next week.

    Thanks.

    John

  • In reply to feng John:

    Hi John
    Have you tested this configuration on your with your board?

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    Please click "This resolved my issue" button if this post answers your question.

    For more information on Battery Charger Solutions see Link

    Tip -- Improve search results by including "FAQ" 

  • In reply to Bill Johns:

    Hi Bill:

    No, I cannot just test one board to reach a conclusion. This question should be answered by the application or designer.

    Could you check with the designer whether I can do the following two things:

    1. I am thinking of shorting 4 pins: USB, BAT/OUT1, BAT/OUT and CE to the new 6.8v battery, is it OK? basically I am using bq25010 only as a buck converter to generate 3.3v for my board.

    2. if I tie EN and CE pin permanently to 6.8v, will it be ok? any long term reliability issue? the datasheet only specify absmax for EN is 7v, but didn't specify absmax for CE pin.

    Please advice.

    Thanks.

    John
  • In reply to feng John:

    Hi John
    I am checking with design but the BQ25010 is an older design released in 2003, this will make study of the question difficult.

    The other question that came up was regulation accuracy of the 6.8V charger. It will need to have a very tight regulation to keep from going above 6.8V.

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    Please click "This resolved my issue" button if this post answers your question.

    For more information on Battery Charger Solutions see Link

    Tip -- Improve search results by including "FAQ" 

  • In reply to Bill Johns:

    Hi Bill:

    the nominal voltage for my charger output is 6.5v, max 6.8v.  that's why I used maximum voltage 6.8v in my questions.

    let me re-phrase my questions:

    1. I can tie CE pin to 6.8v, to disable the charger, use bq25010 only as a DC-DC converter, right?

    2. is bq25010 still in mass production?  or there is a newer version that's pin to pin conpatible?

    THanks.

    John

  • In reply to feng John:

    Hi John

    "1. I can tie CE pin to 6.8v, to disable the charger, use bq25010 only as a DC-DC converter, right?" -- Bill J - I will have to get input from design before I can give you an answer on this. Suspect CE is ok to 7V. Running the buck at 6.8v long term, raises question about reliability, transient response, voltage spike on the switch node and others.

    "2. is bq25010 still in mass production? or there is a newer version that's pin to pin compatible?" -- Bill J - The bq25010 future is TBD, it is now in review. No pin to pin devices.

    I would like to know more about your application and circuit. Can we move this discussion off line?

    Best Regards,

    Bill Johns,  Applications Engineer

    Texas Instruments Inc

    Dallas, Texas

    Please click "This resolved my issue" button if this post answers your question.

    For more information on Battery Charger Solutions see Link

    Tip -- Improve search results by including "FAQ" 

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.