I use LM2576 as a symbol here, sure I used full circuits components like the image below.BigBoss: Is the actual circuit like that or ? Because the application circuit of LM2576 is not like that and if you haven't applied the necessary components, your circuit may oscillate and it would destroys all.....
For example when the load is 200mA and the power supply is 24V/500mA this problem exist but with same load when the power supply is 24V/1000mA the problem gone.FvM: The question is unclear. "VCC feed with less than 1AMP" suggests a current limited source. "Input Voltage is 24V" means no current limit...
I see, that's expectable by design. Get rid of the misbehaving Z-diode and MOSFET circuit and control LM2576 on/off pin by voltage threshold detector.For example when the load is 200mA and the power supply is 24V/500mA this problem exist but with same load when the power supply is 24V/1000mA the problem gone.
The mosfet rating is 500V,2.4A,42W so for sure with 200mA load it wont be an issue.
At the problem point I see the Gate voltage is about 3.5V so I think the mosfet is not turn on completely and by measuring the mosfet output it confirm which it is not on.
You just read the three values. But you need to read the conditions to the specifications, too.The mosfet rating is 500V,2.4A,42W so for sure with 200mA load it wont be an issue.
You are completely right and this is my issue which MOSFET is not working properly, could you please give me some ideas what are those considerations and what is better way which you mention before.As already confirmed by Sharagim, the posted circuit has the unwanted side-effect to stay in a linear MOSFET operation point under certain source and load conditions....
Could you please let me know if you believe this threshold detector should be build with OPAMP !?FvM: . Instead of controlling the gate voltage with a Z-diode, you should use a threshold detector with hysteresis,
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