ltc4359 Increasing Vout transistor stop work

Hello everyone 

I'm facing a problem in my circuit with LTC4359, when my output exceed the input voltage LTC4359 stop working.

I would like to mainten my LTC4359 even if my output exceed the input. Theres is a way to do it?

Regards,

Bengui



problem
[edited by: ge16 at 2:54 PM (GMT -4) on 27 Oct 2020]
  • 0
    •  Analog Employees 
    on Oct 27, 2020 7:22 PM 1 month ago

    Hi Bengui,
    If I understand you right, the LTC4359 is behaving as intended. Remember that the part is an ideal diode controller, and diodes only conduct in one direction. When OUT-IN ≥ 30mV, the LTC4359 turns off the transistor. Can you tell me more about your application and post a schematic?
    -Aaron

  • Thank you for your Reply Aaron,

    In my application i'm supplyng a system and charging a battery, Vbat exceed Vin and the LTC4359 stop working, as you explain it's a normal behavior of this component. I would like to maintain VIN even if the battery is completly charged and use it only for back-up VIN=0.

    Bengui

  • 0
    •  Analog Employees 
    on Oct 28, 2020 9:15 PM 1 month ago in reply to ge16

    Hi Bengui,

    It's strange how the battery became a greater potential than the supply recharging it. This would be temporary, as the battery would eventually discharge to be 30mV less than the supply.

    I found something that may be closer to what you want using the LTC4412 powerpath controller. If you look at the figure 3 in the datasheet, the circuit is similar to the application you describe. I modified this circuit to behave like you requested:

    1) The supply is charging the battery (when VIN + ~300mV > VBAT)

    2) VIN has priority over VBAT (CTL tied to VIN)

    3) VBAT only used when VIN=0 (VIN < 650mV is the best this circuit can do)

    I don’t know what voltages and load current you are working with, so I just picked something. The diode and FET models are also placeholders. I’ll give you the simulation file so you can play around with it. Let me know if this works.

    -Aaron
    4412 4359 EZ question.asc

  • Thank you for your reply Aaron,

    I will see the option that you suggested to me, for my application the LTC4359 does not seem to work as well, I have a confirmation for a few minutes and then Vbat feeds the system.

    LTC4412 will not work for my system, my Vin is 51V.

    Bengui