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

I was just researching this myself today. Linear Technology makes some nice
power-management chips. For your application, you might take a look at the
LTC4365 <http://www.linear.com/product/LTC4365>, which provides undervoltag=
e,
overvoltage and reverse-voltage lockout with low overhead.

For my own application, I'm looking at the LT4356 to provide additional
robustness when my system is powered from 12V or 24V vehicle power buses.

I already use the LTC4210 hot-swap controller as a software-controlled swit=
ch
and overcurrent protector to manage peripheral loads in one of my systems.

-- Dave Tweed
--=20
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