I have double checked it and it is wired correctly. Could there be any leakage through PMOS? Since when I put an oscilloscope probe to Enable signal it works as expected. Without it I can not switch PMOS off. I guess the autostart does not work and a device is switched on because of the leakage as well? Any idea, please?

Change Q1 circuit to this:

 

Change Q1 circuit to this:

View attachment 364150

Thanks, what is the reason for this change?

 

I have double checked it and it is wired correctly. Any idea, please?

The key to the shutoff is in the programming of the micro.
The micro must deactivate the output pin latch only after the switch is released with a short 100ms pause.

 

Thanks, what is the reason for this change?

The 1M values are too high.
D2 provides quick discharge.
D1 prevents voltage feeding back into mcu output.

 

The key to the shutoff is in the programming of the micro.
The micro must deactivate the output pin latch only after the switch is released with a short 100ms pause.

Ok, how to do that to be independent on that short time?

 

Don't need to change the input circuit on my design.

 

The 1M values are too high.
D2 provides quick discharge.
D1 prevents voltage feeding back into mcu output.

I have changed the circuit but there is the same issue. When I put an oscilloscope probe to enable signal, it works as expected :-(.
BTW do you think I can use LTC2954 in some way?

 

I have changed the circuit but there is the same issue. When I put an oscilloscope probe to enable signal, it works as expected :-(.
BTW do you think I can use LTC2954 in some way?

are you testing with mcu? Which one?
Which signal is the enable signal?

 

BTW do you think I can use LTC2954 in some way?

You mean instead of LM2596? Yes.

 

You mean instead of LM2596? Yes.

No, I mean instead of the whole circuit.

 

No, I mean instead of the whole circuit.

in what way?

 

in what way?

I mean for autostart of power supply for MCU and using KILL signal to switch it off and toogle button to switch it on again. Or LTC2955...

 

I mean for autostart of power supply for MCU and using KILL signal to switch it off and toogle button to switch it on again. Or LTC2955...

What is the total 24v supply load current? Is it resistive or inductive?
What is the total 5V supply load current?

 

What is the total 24v supply load current? Is it resistive or inductive?
What is the total 5V supply load current?

24V - up to 8A
5V - up to 6A

 

24V - up to 8A
5V - up to 6A

LTC2955 or LM2596 won't work. Need a higher current switched regulator.

 

LTC2955 or LM2596 won't work. Need a higher current switched regulator.

Not sure why, because I want to use EN output for MCU power (SMPS) enable. Why do you think there is any issue with the load current?

 

Not sure why, because I want to use EN output for MCU power (SMPS) enable. Why do you think there is any issue with the load current?

sorry, misread the datasheet.
LTC2955 may have possibilities.
The LM2596 won’t work for 6A.

 

Which mcu are you using?

 

Which mcu are you using?

This is for tria c6c tlu module.

 

This is for tria c6c tlu module.

so…what will be used for digital I/O?