LT4356-1 & LTC4364-2 negative protect

Hi,

With a Ideal Diode function (LTC4364-2), it has a unique technique.

If reverse current develops, a 130mA fast pull-down circuit quickly
connects the DGATE pin to the SOURCE pin, turning off the MOSFET.

But why this operation can Holds Up Output Voltage ?

Now we use LT4356-1 for the negative test and the standard need hold up for a while.

We usually add large capacitor for the specific period.

We would like to know if have a design change to LTC4364-2 can save the capacitor and volume ?

Thank you for your kind assistance !

  • HI Snow.Hung,

    Your interpretation is right . With its Ideal diode functionality LTC4364 isolates the output from input completely in case reverse current develops and hence the output voltage is held up in case of input short etc.

    With the LTC4356 surge stopper you might need a larger cap if you want to hold up output for some duration whereas with the ' SS + Ideal diode ' part like the LTC4364 , output will remain charged (unless there is large resistive load to discharge it) with a comparatively smaller capacitor. Note you still need a minimum 22 uF output bypass capacitor with the LTC4364 as well .

    Hope this helps!


    Best Regards,
    Ritesh