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Adding reverse input protection capability to the LTC4421

Category: Hardware
Product Number: LTC4421

Dear ADI team,

we are currently using the LTC4421 in a design where we have the capability to hot swap between two independent power sources. The nominal input voltage for both channels is 12V with an expected load current of up to 20A. The LTC4421 features OV/UV/OC lockout and additionally gives feedback regarding the validity of each channel to an external microcontroller. For these reasons we would like to continue using the mentioned IC in our design. 

However reverse input polarity protection is not provided with this IC and because of that we are considering using and ideal diode controller (such as the LTC4372) that is placed before the LTC4421 in the power path. We are considering such diode controllers as the maximum expected load current can be up to 20A, therefore a reverse polarity protection with a P-MOSFET would be inefficient. Is it possible to include such a controller before the LTC4421 and if yes is what needs to be considered in this case as we now have to independent MOSFETs controlling the power path?

Or is there any alternative solution to the problem? 

Any help is greatly appreciated. A figure of the LTspice simulation as well as the simulation file with the current setup of the LTC4421 is attached below. 

PowerPathController_ltc4421.asc

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  •  ,

    thank you very much for your answer. I added the LTC4372 to the LTspice simulation based on the example circuit shown in Figure 10 in the datasheet and simulated various conditions. The circuit behaves as expected. However some questions remain unclear.

    1. Are the TVS diodes D1 and D2 still necessary? In the datasheet of the LTC4421 it is stated that these diodes are there in order to clamp the peak input voltage due to input inductive energy at channel turn-off. Can this be fulfilled just by the TVS diodes D5 and D6 directly at the power input?
    2. In this kind of configuration, do the output capacitors of the LTC4372 have any purpose or can they be omitted?

    Thank you very much for your help.

     Regards,

    Nikita