LTC4013 FB Pin and Battery voltage

Hi I'm designing a charger for 4 series LifePo4 Batteries the total battery stack is nominal 12.8V. The max charge voltage for this battery stack is 14.4V or 3.6V/cell. The Datasheet doesn't mention how to set up the FB pin for different battery voltages and chemistries?

I've read somewhere on this forum that the FB pin voltage must be set to the single cell voltage of the battery pack. But I've also read here that the LTC4013 doesn't know how many cells its charging? So how would it determine the max charge voltage for the battery stack ?

So my question is how would I go about setting a max charge voltage of 14.4V? Also the FB pin is pulled up to batt which is obviously not fixed?

Parents
  • 0
    •  Analog Employees 
    on Oct 8, 2020 6:59 PM 3 months ago

    Hello,

    You do set up the FB voltage divider based on your stack voltage. Table 1 in the datasheet gives the FB voltages for various stages of operation. To choose your target charge voltage, you must then choose the voltage divider values accordingly.

    I've read somewhere on this forum that the FB pin voltage must be set to the single cell voltage of the battery pack.

    False!

    But I've also read here that the LTC4013 doesn't know how many cells its charging?

    True!

    So, to choose your charge voltage, first choose a chemistry-based charge profile (MODEx pins) and then use Table 1 to determine your FB voltage in each stage of charging. From there, you can choose your FB resistor values.

    Regards,

    Zack

Reply
  • 0
    •  Analog Employees 
    on Oct 8, 2020 6:59 PM 3 months ago

    Hello,

    You do set up the FB voltage divider based on your stack voltage. Table 1 in the datasheet gives the FB voltages for various stages of operation. To choose your target charge voltage, you must then choose the voltage divider values accordingly.

    I've read somewhere on this forum that the FB pin voltage must be set to the single cell voltage of the battery pack.

    False!

    But I've also read here that the LTC4013 doesn't know how many cells its charging?

    True!

    So, to choose your charge voltage, first choose a chemistry-based charge profile (MODEx pins) and then use Table 1 to determine your FB voltage in each stage of charging. From there, you can choose your FB resistor values.

    Regards,

    Zack

Children
No Data