LTC4380-4 Gate Voltage Issue.


We are using LTC4380-4 in one of our project for the Surge Protection, Reverse Protection & Over Current Application. We are using 50V  -  2Amps rating DC Power supply source as input to the VCC pin of LTC4380-4, But we could not get the output as 50V and there is no current flow in the circuit.PDF

When we probe at the Gate Pin of LTC4380-4, We are getting only 0.8V.

We have followed the schematics as per Simulation Tool LTspiceXVII.

Hereby I am attaching the Schematic of LTC4380-4, And also attaching the Simulated files as per the LTspiceXVII tool.

Please give me a solution and advise if any modifications required as soon as possible.

Thank you.


Amarnath G

  • 0
    •  Analog Employees 
    on Nov 20, 2019 11:06 PM

    Hi Amarnath,  The LTspice simulation has Q2 backwards but schematic PDF has it oriented correctly. Per datasheet pages 8 and 14, 22uF is needed on OUT pin. Since the 50V supply is limited to 2A (below LTC4380 6.25A limit), using a >2A load will collapse the input supply voltage. I hope you are applying supply to P50V_IN, not directly to LTC4380 VCC pin.

    Here are some debug tips: Please double-check your board connections and FET orientations. Check that the IC or FET is not damaged. Start with a lower voltage input and no load current. Double-check all pin voltages: e.g., is the ON pin above its 1.05V threshold? For further questions specific to your circuit, please submit a Technical Support Request form: