LTC4367 problem

Hi Analog and Linear experts,

I used LTC4367 as a protection for power section of my board. as you see in attached image the circuit is like what said in datasheet. but it doesn't work even in normal range of voltage like 12V. in the output of this IC we have LTM4636 without any load it consume just 200mA.

The output of LTC4367 goes on and then suddenly goes low without any reason. I changed all ICs but problrm has not been solved. when output is high voltages are: VIN=12V, Vsh=11.8V, Vuv=1.4V, Vov=0.4V

when it is off: VIN=12V, Vsh=0V, Vuv=0, Vov=0

I changed R181 to 330ohm result in off : VIN=12V, Vsh=11.8V, Vuv=3.3V Vov=1.5V

please help me I am really confused,

any help would be greatly appreciated,

Siyavash  

  • 0
    •  Analog Employees 
    on Jan 18, 2018 1:02 AM

    Hi Siyavash,

    Sorry to hear your having these issues. It may be due to the fact that your hitting OV. You mentioned that the device comes up but then turns off. Your OV level is 0.4V which is very close to 0.5V trip threshold. Is it possible that happens due to an unregulated supply or because you change the input voltage?

    Also another point is that you mentioned that when the output is 0V, you see 0V on Vsh, Vuv and Vov. That shouldn't happen if your resistors are connected as shown in the schematic and if you have VIN = 12V present, because those nodes would be pulled up.

    In your last example where you mentioned that you change R181 to 330ohms, you are hitting OV as your OV voltage is 1.5V.

    To be in inside a valid window of operation your OV value needs to be below 0.5V and your UV value needs to be above 0.5V.

    Hope this helps.

  • Hi,

    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 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 Aug 2, 2018 4:01 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin
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