I have a product that would normally be used with a DC input of 12V -=20
36V.  It uses an LM2575 switching regulator to derive the 5V rail (@ few=20
100 mA) for a PIC and other chips.

The lowest of the maximum Vdd ratings on these chips is 6V.  There is a=20
situation where some customers may need to power the board from 5V.

I can provide jumpers to bypass the regulator section, but would like to=20
protect the 5V chips from accidental connection of a higher voltage=20
while still jumpered for 5V.

Looking at transorbs and zeners (with a series fuse or polyswitch) gives=20
me the impression that they will not save the logic chips being=20
toasted.  Any ideas?
David...

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___________________________________________
David Duffy        Audio Visual Devices P/L
Unit 8, 10 Hook St, Capalaba 4157 Australia
Ph: +61 7 38235717      Fax: +61 7 38234717
Our Web Site: www.audiovisualdevices.com.au
___________________________________________

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