AVR-Chat

On Wed, Nov 19, 2008 at 4:30 AM, mago Umandam <magzky02@yahoo.com> wrote:
> Yes, Thanks for response. switch regulator seems to be a good solution. i googled and came to the switch regulator LM5008. I have no 1st hand experience in switch regulator. This 8 pin SMT  IC is capable handling 70V drop at 300mA? Datasheet says efficiency is about 82% at 80Vin 300mA. Will order the part and test and see what happens:)

That's not the only solution..

You could implement a switching pre-regulator, to a volt or so above
the linear reg's dropout, and use the linear to de-noise the SMPS
output.
You can select the SMPS operating frequency to fall at the point of
your linear reg's maximum point.

In a lot of bench supplies, they use a relay to switch the line
transformer between two or more output voltages as you change the
voltage setting.

Same idea, keep the dissipation reasonable, but use linear regulation
for easy low noise output.