LTC4015 VSYS PIN in parallel with other VSYS PIN LTC4015

I'm using the DC2039 in order to test the LTC4015 for charging LiFePO4 battery and interfacing the load voltage supply through VSYS. The problem is that measuring the current consumption of my load with a external voltage supply the current is above (15 A) the VSYS output current (10 A). Reading the LTC4015 datasheet it only mentions that changing the RSNSB you can increase the MAX_ CHARGE_CURRENT  but never mention the maximum current capability at VSYS. How can I increase the VSYS current output ? I was thinking by tying the VIN and VSYS pin of two LTC4015 , like two LTC4015 in parallel but just one of them wil charge the battery.  Is this convinient or possible? if not, which could be the solution to increase the output current at VSYS? Or  the output current value depends of the MOSFET (ideal diodes) of the board?

  • 0
    •  Analog Employees 
    on Oct 7, 2019 2:51 PM


    No, you should not connect two LTC4015 units at SYS, and the solution is actually much simpler/cheaper.

    See the RSNSI resistor, this is the one on the input PowerPath which sets the input current limit.

    FYI, the LTC4015 can't actually limit current from VIN to VSYS (see the orientation of the PowerPath FET body diodes), the input current limit just dials back the charge current in an attempt to do so. If you can't physically get the 15A you need from VIN to VSYS, then there may be a component selection problem.