24V to 3.3V

Hi,

I need to regulate 24V down to 3.3V 100-200mA without spending lots of $$$$$...and Amps.

Of course to make things less fun is that the input voltage will drop maybe as low as 10-12V and we don't want to use something similar to LM7805 since they just waste too much power, so I am looking for something with a decent efficiency. Since many many many of these regulators will be connected to the same 24V powerline it is good if the regulator itself doesn't have a high power consumption.

So does anyone have any favorite chip or trick they want to share I would be very grateful.

It is not hard to buy one from national for 5 USD but there has to be other ways to do it.

/me

http://www.romanblack.com/smps/smps.htm with some small changes.

Quote:

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Originally Posted by Jumper

Hi,

I need to regulate 24V down to 3.3V 100-200mA without spending lots of $$$$$...and Amps.

Of course to make things less fun is that the input voltage will drop maybe as low as 10-12V and we don't want to use something similar to LM7805 since they just waste too much power, so I am looking for something with a decent efficiency. Since many many many of these regulators will be connected to the same 24V powerline it is good if the regulator itself doesn't have a high power consumption.

So does anyone have any favorite chip or trick they want to share I would be very grateful.

It is not hard to buy one from national for 5 USD but there has to be other ways to do it.

/me

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use buck regulator application with MC34063A. this is not a costly item. total 6 or 7 components, you get decent control and no power wastage. the chip might cost $0.7 at unit price. If, in bulk, the price drops. thus it may be presumed that under $1.2 you can do it.

I will have a look at your suggested solutions. Thank you very much!

You could also try the LM2574N-3.3. It's a simple little 500mA switcher that can take a supply voltage up to 40VDC and 60VDC in the higher voltage model. We use the 5V and 12V versions in almost all of our products and have no problems with them. They run quite cool too.