Hi all. I'm looking to design an isolated DCDC power supply for a small microcontroller. The requirement is to have 5V 500ma output. In my previous (unisolated) deisgn, I just used an LDO, LP38691DT-5.0, to generate the regulated 5V from 6V coming it. This has worked very well. It has been a stable an inexpensive solution.
However for my next design, I would like to have more flexible input voltage range, say 9-30VDC as well as DC voltage isolation to protect the uC and ADC's so that they can be used in an industrial environment. After doing some research, it looks like you can buy off-the-shelf isolated DCDC converters, like this one, however they are quite expensive, around $15 each.
My guess is they contain high efficiency switching power supplies, and other things that I don't really need (or understand ). Since efficiency really isn't a requirement, is there any reason that I can't just use a 1:1 transformer like this for isolation, followed by a linear regulator with a wider input range, such as this one MC78M05?
What are the tradeoffs for using linear regulators in this application? Even though it specs a maximum input of 35V, is there a problem running with such a high in/out differential, say 24V stepping down to 5V? Why are the off the shelf isolated low current DCDC converters so expensive? Will the transformer give me the protection that I need in an industrial environment, or should I be looking at more complex regulators?
Thanks in advance for your help.
However for my next design, I would like to have more flexible input voltage range, say 9-30VDC as well as DC voltage isolation to protect the uC and ADC's so that they can be used in an industrial environment. After doing some research, it looks like you can buy off-the-shelf isolated DCDC converters, like this one, however they are quite expensive, around $15 each.
My guess is they contain high efficiency switching power supplies, and other things that I don't really need (or understand ). Since efficiency really isn't a requirement, is there any reason that I can't just use a 1:1 transformer like this for isolation, followed by a linear regulator with a wider input range, such as this one MC78M05?
What are the tradeoffs for using linear regulators in this application? Even though it specs a maximum input of 35V, is there a problem running with such a high in/out differential, say 24V stepping down to 5V? Why are the off the shelf isolated low current DCDC converters so expensive? Will the transformer give me the protection that I need in an industrial environment, or should I be looking at more complex regulators?
Thanks in advance for your help.