I have a small number of 7805 voltage regulators in to220. Data sheet puts operating temperature at 0to85c. Want to use one to power a heated mirror timer in my truck, would often be run considerably below 0.
I don't think it's a big deal, circuit would be fused, and simple enough if it dies I can just order better parts and do it over.
Is this likely to work, and what's the worst that could happen?

 

Doubt you'll have much issue's with it, 7805 seems good enough for many simple auto applications. You could get all technical for it and I am sure members will but.. meh...

 

I can buy 7805s with an operating range of -40 to +85, but just happens I already have a bunch, but I bought them not thinking about running them cold.
Even if they have a shorter life, i can cross that bridge when I get there

 

Presumably there will be some voltage across the regulator and power being dissipated. That would provide some self heating.

In any case, just get the extended temperature range part and save the others for another project.

 

I am considering that. It's just that I already have everything I need, except that extended temp part

 

For that application, I will have no qualms using a 0 to 85 °C voltage regulator.

In the "deep freezer" at worst, I think the output voltage may be 50 mV further away from the nominal value.

 

You could knock up a test circuit and see how it behaves in a domestic freezer.

 

When semiconductors get cold they don't work as well. Your voltage may be off, the regulation might not be as good, but if the work, you probably aren't shortening their lives. Go for it.

 

It may go some outside its spec voltage limits below 0°C but that's unlikely to be a problem in your application.

As suggested you could test the circuit in your freezer.

 

Do they actually make different chips for the extended temperature range?

Or is just more testing/higher price?

 

Do they actually make different chips for the extended temperature range?

Or is just more testing/higher price?

I think it's the same chip with more testing.