Hi, I'm looking for a schematic to achieve the following:

If input voltage is below 9V then output 0V, if voltage is above 9V then output input voltage.

Max current - 4-5A
Max voltage - 14V

I tried using tl431 with irf5305, but can get it working.
Here is my schematic, it works on a test board, but when I solder it behaves weirdly. Sometimes voltage is negative, sometimes MOSFET is open on any voltage applied.


Could someone help with a nice schematic to achieve this?

Kind regards

 

Which side do you consider the input and which the output?

 

Use the Tl431 as the reference voltage on a LM393 comparator to switch the mosfet.

 

If You want exactly ~9-Volts, change R-1 to a 2,610-Ohms, 1% Resistor.
Then figure-out where your bad solder joint is.
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