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BQ2970: Choosing the right battery protection circuit variant

Jorge De La Rocha
Prodigy 150 points
Part Number: BQ2970

I need help in choosing the correct part among the different variations you offer.

BQ297xx Cost-Effective Voltage and Current Protection Integrated Circuit for Single-Cell Li-Ion and Li-Polymer Batteries datasheet (Rev. G)

 

The battery we plan on using is this one:

https://www.batteryspace.com/polymer-li-ion-cell-3-7v-1050mah-553562-10c-3-8wh-10a-rate---un38-3-passed-0-315.aspx

 

This battery is capable of discharging at 10C max. although we won’t necessarily connect an external load which would cause such a high current, I’d like to understand how your IC determines how much discharge current is too much? There are no current threshold settings on your part.

  • 0
    TI__Guru* 79043 points

    Hi Jorge,

    Have you looked at Section 10.2 of the datasheet - this shows a detailed design procedure example for a specific set of design parameters. The BQ2970 does not have a sense resistor, so FET selection based on RDson is very important since the current thresholds are based on the voltage drop across the FETs. 

    I recommend first narrowing down the part number selection in Table 5 of the datasheet based on the over-voltage and under-voltage thresholds you need. For example, it looks like you need an under-voltage protection limit of 2.5V based on your battery specification. 

    Best regards,

    Matt