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BQ77915: pairing bq77915 with bq77216

Muki
Prodigy 110 points
Part Number: BQ77915
Other Parts Discussed in Thread: BQ77216

Hey Guys,

I'm having difficulties pairing bq77915 with bq77216 for LFP chemistry

i thought of pairing bq7791514 (3.65V OVP) with bq7721611 (3.8V OVP), but it seems that bq7791514 has been discontinued.

if i go with bq7791506 instead (3.8V OVP) then bq7721611 (3.8V OVP) could trigger the fuse during regular use and bq7721614 (3.9V OVP) seems unavailable too

A. Is the 3.8V OVP of bq7791506 safe instead of 3.65V for LFP ?

B. pls suggest a suitable combination or an alternative for this scenario

C. what about the bq769X2 ? are there any reference designs that doesn't use a microcontroller ?

appreciate the help

thanks & Regards

  • +1
    TI__Expert 4465 points

    Hi Muki, 

    The BQ7721614 (3.9V) is about to be released to market, so it'll be available on the web within the next month. I guess by then you can use the BQ7791506 alongside the BQ7721614 for your application. 

    For the BQ769x2, it can be use as standalone (without an MCU). I don't believe we have a TIDA design for use as a standalone solution, but you can use the EVM https://www.ti.com/tool/BQ76952EVM as a design starting guide and omit the MCU. The section 16.6 Unused Pins of the datasheet https://www.ti.com/lit/ds/symlink/bq76952.pdf goes into the details of what to do with unused pins, and Section 12.4 of the D/S talks about standalone vs host configuration. 

    Regards, 

    Arelis G. Guerrero 

  • 0 in reply to Arelis Guerrero
    Prodigy 110 points

    Hey Arelis,

    thank you for the clarifications

    As for the bq7791506, have you had any queries from customers stating that the 3.8V OVP is too high ?

    was there a reason for Ti to have chosen 3.8V over the standard 3.65V ?

    just curious

    Thanks & Regards 

  • +1 in reply to Muki
    TI__Expert 4465 points

    Hi Muki, 

    The spins of the protectors are normally tied to a specific customer, trend, or battery application. Most customers with Li-Ion have an operating voltage around 3.65V, so they don't want their OVP around voltage regulation, but a little bit higher. This is why most of the spins used values >3.8V for over voltage. For LFP chemistry the operating is around 3.2V so a 3.65V OVP is more applicable on this scenario. The protector is independent of battery chemistry and we have different versions to target most of them and can evaluate spins generation based on business case for any family of devices. At the end, is all related to the battery they are using and the battery requirements for protection.

    For more flexibility and a configurable OVP threshold using the BQ769x2 would be a better alternative as you can set the OVP from 1.102 to 5.566V in a 50.6mV steps. This device also allows you to configure most of the other protection parameters and can be OTP programmable to the settings needed for your application at the customer production line. 

    Regards, 

    Arelis G. Guerrero

  • 0 in reply to Arelis Guerrero
    Prodigy 110 points

    Hey Arelis,

    i understand now

    can you confirm whether the bq7791514 (3.65 OVP) is out of production ? will it be available in the market again ?

    meanwhile, i will look into the bq769x2 monitors

    Thanks & Regdards

  • +1 in reply to Muki
    TI__Expert 4465 points

    Hi Muki, 

    The BQ7791514 is a new spin that will also be release to market within this month, so it'll be available soon on the web for orders. 

    Best regards, 

    Arelis G. Guerrero