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    LTC4020 buck/boost battery charger - Charge/ Discharge current

    Hello,
    I am designing battery charger for 12V battery using LTC4020. from datasheet of IC, i found Maximum Charge current will be programmed by Rcs sense resistor value between CSN and CSP pins. so i want to ask that can i program charge and discharge current rate different? for example if i set charge current to 4A so can i set discharge current from battery will be greater than this let say 8A or anything else than 4A?

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    Re: LTC4020 buck/boost battery charger - Charge/ Discharge current

    Hi,

    I'm not sure I understand what you mean. One thing is unrelated to the other, I think; it looks to me like: yes, so long as the battery is given enough time to be charged, and the charging current will be set by the type of battery anyway. I think the problem is more one of allowing for adequate charge time than of different current values.



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    Re: LTC4020 buck/boost battery charger - Charge/ Discharge current

    Hi,
    Yes. That is Right but i want to know that if battery is capable to supply more current then that Rcs sense resistor will limit current from battery?



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  4. #4
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    Re: LTC4020 buck/boost battery charger - Charge/ Discharge current

    Hi,

    I haven't read the whole datasheet, but if it's anything like the LTC4079 - the IC is only on and supplying battery and load when the battery is charging, when it's charged the IC switches off and the battery supplies the load, until the battery voltage reaches the level programmed to start charging the battery and supplying the load in the meantime, again. You'd have to read it to find that information in the extensive theory of operation section.

    If it works that way, then one thing to consider is if e.g. 8A * 0R02 = 160mV is too high a voltage drop for the output needed.

    There are different schematics in the datasheet, which are you referring the question to? Page 38 shows a Li-Ion charging circuit with 2.5A charging limit and 3.5A out, so "presumably" not.



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