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Can I use ICM7555 IC to generate 300 KHz PWM signal and feed that PWM to IRL2104 mosfet driver to build a non-isolated DC to DC buck converter?

I'm asking this question because I couldn't find any decent buck converter design using CMOS 555 timer that have voltage feedback and a mosfet driver, thought to myself maybe it is not possible or at least the idea may have fundamental problems.

I've very little knowledge about switching power supplies, go easy on me.

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    \$\begingroup\$ Is there a reason to use a 555 for this? Chips specifically meant for building buck converters exist, integrated with features that need to be externally implemented with separate components. \$\endgroup\$ – Justme Sep 20 '20 at 13:04
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    \$\begingroup\$ guess one can use a 555 for a buck converter, but why? better IC's are not really more expensive and with higher frequ. your inductance gets smaller, smaller ripple,... so its more a lecture for trainees than a practical consideration,... \$\endgroup\$ – schnedan Sep 20 '20 at 13:06
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    \$\begingroup\$ Here's the generic answer: I couldn't find any decent buck converter design using CMOS 555 \$\endgroup\$ – Andy aka Sep 20 '20 at 13:08
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    \$\begingroup\$ A 555 seems to be the wrong choice here – either you're building something open-loop, in which case you'll have no feedback and no real regulation, or you're building something closed loop, and then your 555 becomes nothing but an inelegant method to solve a small subproblem of the overal converter problem; you'd simply not do that, but use one of the many (cheap!) existing buck converter / controller ICs. In your case, the low-power IRL2104 implies that even the very classic ICs will do that at a much lower cost, probability of failure, complexity. \$\endgroup\$ – Marcus Müller Sep 20 '20 at 13:14
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    \$\begingroup\$ @Fredled: There's plenty of fixed-frequency buck converters out there, and a 555 can be easily made into a variable-frequency device by changing the voltage on the threshold pin or by adding external circuitry -- so, wrong on both counts. \$\endgroup\$ – TimWescott Sep 20 '20 at 17:36
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A 555 seems to be the wrong choice here – either you're building something open-loop, in which case you'll have no feedback and no real regulation, or you're building something closed loop, and then your 555 becomes nothing but an inelegant method to solve a small subproblem of the overal converter problem; you'd simply not do that.

Instead, you'd use one of the many (cheap!) existing buck converter / controller ICs. In your case, the low-power IRL2104 implies that even the very classic ICs will do that at a much lower cost, probability of failure, complexity.

In other words the question "how to build a buck converter with a 555" is as far as I can see answered by "use the 555 as decoration only, and design a proper buck converter without it", just as "how do I design an airplane with chocolate pudding" with "use the pudding elsewhere and design the aircraft without pudding. Pudding doesn't help when building aircraft."

Also, fully aware that you might be subject to availability restrictions, but last time I checked a classic MC34063 (or clone thereof) isn't any more high-tech than a CMOS 555.

To be absolutely clear: if you can buy more modern ICs, don't buy the MC34063. It's really ancient (1983), and voltage converters have progressed a lot in the last four decades; buy something modern, which will have better ripple and regulation, higher efficiency and need a smaller inductor. Using a low-tech MC34063 is just still better than trying to shoe-horn a 555 into the job of a converter controller.

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    \$\begingroup\$ But - if you live somewhere where you can get up to date components, the MC34063 probably only belongs in a nostalgia project. \$\endgroup\$ – TimWescott Sep 20 '20 at 17:33
  • \$\begingroup\$ Fully agreed. but aside from the cheapness, point was: by 1983, the MC34063 was available; I can't find out whether that predates the CMOS ICM7555, but it's about as high-tech as being able to buy sliced bags in plastic bags and should be as available. \$\endgroup\$ – Marcus Müller Sep 20 '20 at 18:37
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    \$\begingroup\$ Oh, absolutely. Both of those chips are old enough to buy alcohol, twice over. I just don't want someone stumbling across your answer and thinking that the MC34063 should be their go-to chip. \$\endgroup\$ – TimWescott Sep 21 '20 at 0:14
  • \$\begingroup\$ @TimWescott oh! Yes. Added a closing paragraph. thanks! \$\endgroup\$ – Marcus Müller Sep 21 '20 at 7:31

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