Voltage Drop Alternatives for Analog Power Circuit.

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witssq

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I would like to design Power supply with very stable and low ripple for analog measurement application.

For regulation from +15 to +5V, from -15 to -5V 3A, about 3Vx3A voltage drop is needed for too much heat.

Please advice me a better alternative for voltage drop under stabilty and ripple basis.
Which one would be better among (1)- wirewound resistor and (2) diodes alternative as attached?
Or does any other better alternatives exist?

Awaiting kind response,
Thanks.
 

I do not understand your calculation of 3Vx3A. Are you wanting to drop from 15V to 5V at 3A? That is a 10V drop and so 30W, plus the same for the -15V. That is a lot of power. You would be far better to look at switching regulators and add some good filtering. Have a look at the power supply design tools on manufacturers' web sites such as www.National.com

Keith
 

Hi, Keith


The voltage drop needed is 3Vx3A, the remained voltage drop would be covered
by regulator.

Thanks,
 

witssq said:
The voltage drop needed is 3Vx3A, the remained voltage drop would be covered
by regulator.

Thanks,
Click to expand...

Ok. My earlier comments still apply - use a switcher! If you really don't want to rely on filtering you could regulate with a switcher to maybe 0.5V above the desired voltage and use a low dropout linear regulator to drop the rest.

Keith.
 

Hi,

Thanks for your comment.

Not good-experienced, I would like to know what switcher mentioned is.
If possible, please let me know where I find sample schematic.


Best regards,

SunSung Hwang
 

Go to www.national.com At the top right you should see "WEBENCH designer". Type your requirements in then and click "start design". A new window will appear with a choice of chips which will do the job. It also losts cost, size, number of components, efficiency etc. Pick one and it will show you the design and parts list. I have attached an example.

Keith.

 

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