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Use LTC4412 in My DC UPS

My DC UPS prototype

Hi!

I need help building a DC UPS. Did I understand correctly the idea of using LTC 4412 to control fully isolated MOSFET switchs? I am suggesting to use an external switching power supply (Wall Adapter) and a backup 12V gel or LiFePo4 battery. For periodic recharging of the battery, I plan to use a separate charging module, which will connect if there is power from the Wall Adapter and if the battery voltage is below 11 volts. The charge module will be connected to the battery with a VT5 transistor. The entire circuit will be controlled by a separate microcontroller.

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  • Hi Alex,

    Your circuit resembles figure 4 in the datasheet, so it will should work.

    The primary power source is connect to VIN. In your case: the wall adapter.

    Will the wall adapter always be present?

    It seems like the battery is the power source that will always be present.

    If the wall adapter is unconnected, DA1 will not have power, and even if the battery is connected, the load will not be powered.

    Regarding the battery charging section: when the MCU commands DA2 off, current can flow through VT5’s body diode and into the battery if the charger's output ≥ BAT1+0.7V. If you want the MCU to disconnect the charger from the battery, use back-to-back PFETs like your other circuit.

     

    -Aaron

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  • Hi Alex,

    Your circuit resembles figure 4 in the datasheet, so it will should work.

    The primary power source is connect to VIN. In your case: the wall adapter.

    Will the wall adapter always be present?

    It seems like the battery is the power source that will always be present.

    If the wall adapter is unconnected, DA1 will not have power, and even if the battery is connected, the load will not be powered.

    Regarding the battery charging section: when the MCU commands DA2 off, current can flow through VT5’s body diode and into the battery if the charger's output ≥ BAT1+0.7V. If you want the MCU to disconnect the charger from the battery, use back-to-back PFETs like your other circuit.

     

    -Aaron

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