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Li-ion battery charger ic suggestion

Jonathan Navor
Genius 9475 points
Other Parts Discussed in Thread: TPS40210

Hi team,

Good day! Could you help us looking for a battery ic or a combination of ics that can meet the following customer's requirements: I already suggested some part but did not meet all the following requirements below. 

1 - AC/DC adapter voltage output = 24V

2 - System load= 20A at 24Vdc.

3 - Battery charging current = 6A

4 - Battery nominal voltage = 25V

5 - Battery max charge voltage is 29V when charge up from step 1 (AC/DC input is 24V max.)

6 - Battery output (29V) needs to be regulated to 24V to power up the system load.

7 - SMBus interface

Do wa have this kind of Li-ion battery charger ic? 

Thank you so much for your support. 

Best regards,

Jonathan

  • +1
    TI__Guru**** 154696 points

    Hi Jonathan,

    Unfortunately, TI currently does not have a single IC charger solution for this application.  Even if we did, our charger topology does not post regulate the battery down to a lower voltage so a buck converter following the battery would be required.  I recommend searching the reference design database at https://www.ti.com/reference-designs/index.html.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    TI__Genius 9475 points

    Hi Jeff,

    This is a continuation from this query and requested by our customer to look further. 

    How about a  battery charger  that can support 7 cells in series. the input voltage to the ic is 24Vdc and  a boost regulator to boost 24V to >30V to charge up the battery with 6A? 

    Thank you so much. 

    Best regards,

    Jonathan

  • +1 in reply to Jonathan Navor
    TI__Guru**** 154696 points

    Hi Jonathan,

    TI currently doesn't have a charger that charges more than 5 LiIon cells (21V) or accept higher than 26V input (and therefore pin) voltage. In order to regulate charge current and charge voltage, one of the charger pins must connect to the battery.  So having a boost converter follow the charger would only provide constant voltage regulation, not constant current.

    Regards,
    Jeff

  • 0 in reply to Jeff F
    TI__Genius 9475 points

    Hi Jeff, 

    Thank you for your effort to check this customer's concern. However kindy please explain to us what do you mean with 

    Jeff F said:
    one of the charger pins must connect to the battery.

    We agree with you on 

    Jeff F said:
    So having a boost converter follow the charger would only provide constant voltage regulation, not constant current.

    do you have any suggestion on how to implement this?

    Best regards,

    Jonathan

  • 0 in reply to Jonathan Navor
    TI__Guru**** 154696 points

    Hi Jonathan,

    Our charger pins' abs max voltage ratings are 30V. The SWx/PH and SRN pins could be damaged if connected to a 7s = 29.4V battery pack. 

    My recommendation is a multichip, discrete reference design using a voltage regulating boost converter (TPS40210 for example) to provide constant voltage with INAXXX or similar current sense IC to measure charge current and feedback to the boost converter to clamp the charge current.  Then use  a buck-boost converter to provide the 24V system rail from the battery when the AC/DC is not attached.  You might need ideal diode OR ICs to OR the 24V AC/DC to the output of the buck-boost converter.   

    Regards,
    Jeff

  • 0 in reply to Jeff F
    TI__Genius 9475 points

    Hi Jeff,

    Thank you so much. Our customer had read your responses and suggestion but since our customer can not reply to this thread, I am posting on their behalf. 

    Here it is:

    "My idea is to boost first the voltage before the charger ic (35V). Then have the charger ic directly connected to the battery to charge the battery."

    Best regards,

    Jonathan

  • +1 in reply to Jonathan Navor
    TI__Guru**** 154696 points

    Jonathan,

    TI does not have a charger than can accept more than 26V operating voltage, 30V abs max.  The only possible TI solution is a multiple chip, discretely built dc/dc converter plus current sensing circuit like I mention above.

    Regards,
    Jeff