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I'm designing a buck converter to feed the following loads:

A control circuit 3.3V/100mA A 80V solenoid which has a DC resistance of 300 ohms. This means a current of ~270 mA.

My plan is to generate 80V from the buck, followed by another switching regulator to get down to 3.3V.

The solenoid will be ON just for about 30 ms, i.e., no continuous power. The max power for the control circuit is 3.3x100mA = 330mW, that's OK. But the power for the solenoid is 80x270mA = 21.6W. As the solenoid will be ON just for 30 ms, do I really need to design my buck converter to be 22W?

Higher power means higher cost and more vulnerable to thermal issues. I think I can lower the power and use a capacitor to supply the peak current for the solenoid. Any suggestions?

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  • \$\begingroup\$ Have you priced out capacitors able to supply 300 mA at 80 V for 30 ms without the voltage dropping below, say, 70 V? \$\endgroup\$
    – The Photon
    Commented Apr 13, 2020 at 4:08
  • \$\begingroup\$ You haven't mentioned your supply voltage and source. \$\endgroup\$
    – Andy aka
    Commented Apr 13, 2020 at 9:38

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Half-wave rectified 120V is about 80V RMS. if your solenoid has reinforced insulation and is not damaged by half-wave power may only need an SCR!

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