LTC4367 1A load issue


I am using LTC4267 IC as a over voltage protection device. I have set the over voltage to 36v and the device is working fine. I have given a load of 1A. I have given 28v supply and 100V supply using diodes ORing circuit such that

1. If 28V is ON and 100V is OFF, then device input is 28V. The device works fine.

2. If 28V is ON and 100V is ON, then device input is 100V.

In second case when the 28V is ON for some duration, the device works fine and suddenly if 100V is switched ON, then the device gets damaged.

This happens only when 1A load is applied. Without load it works fine for this case also.

I have almost 10 devices like this. 

Please help me to solve this problem.

  • 0
    •  Analog Employees 
    on Apr 17, 2018 7:40 PM

    Can you provide a schematic of your circuit?

  • Here is the schematic I have used. from pruthvikumar

  • 0
    •  Analog Employees 
    on May 1, 2018 1:28 AM


    Thank you for sending the schematic. Where is the 100V being generated from? Is it coming from CAP+?

    Are the MOSFETs still functional?

    It is possible that you are momentarily exceeding the absmax rating of the LTC4367, inductive spikes in your system could exceed the 100V absmax and damage the device. What is the rating of D3? if the maxmimum clamping voltage of this device is greater than 100V then it should be reduced.

    If the problem persists please send this device in for FA so that we can see which pin failed.

  • Hi,

    The 100v is coming from the External supply. The MOSFETs are still

    functioning without any problem.

    The diode D3 is an SMBJ diode with a cutoff voltage of 36V.

    My requirement is that :

    The supply is given as step i.e for time 't1' there will be 28v supply and

    suddenly after 't1' the voltage increases to >40V and continues for

    time 't2'. At that time the output of the device should be 0.

    After 't2' the input voltage again falls to 28v, and at this time the

    output should be 28V.

    The Device works fine exactly as above without any load connected to it.

    But if a load is connected (tried with 0.5A load), then the device fails

    even with a step of 50V.

    Please help me in solving this.

    There are no remaining ICs to test. Could you provide any samples?




    Thanks and Regards

    P.Kumara swamy

    Embedded Engineer

    Sigma Microsystems

    On Tue, May 1, 2018 at 2:58 AM, Sal.Afzal <

  • 0
    •  Analog Employees 
    on May 6, 2018 3:09 AM

    Understood, Where is the 100V supply connected in reference to your circuit? How is it being plugged in? Inductances in the path such as banana cables can cause the voltage to spike above 100V which may be causing damage to the IC.

    I will private message you so that I can get your contact information and we can attempt to resolve this via phone or email.