Hello All,

Thank you for taking the time to read my post. I am working on an 8W outdoor Ku Band BUC that is rated to work from -40 to +40 degrees C, the voltage regulator inside to unit is only rated from 0 to 125 degrees, why is that?

I lose 3dB of power when this thing gets below -30 degrees C

Part number is TL783, I know that there is some self-heating going on but I really don't think that it could make up for a 40-degree differential.

Any insight at all would be great thanks!

 

the voltage regulator inside to unit is only rated from 0 to 125 degrees, why is that?

Perhaps the BUC is only designed to work in a temperate climate? Where do you need to operate it?

 

it goes to North West Territories, definitely -40

 

Hello All,

Thank you for taking the time to read my post. I am working on an 8W outdoor Ku Band BUC that is rated to work from -40 to +40 degrees C, the voltage regulator inside to unit is only rated from 0 to 125 degrees, why is that?

I lose 3dB of power when this thing gets below -30 degrees C

Part number is TL783, I know that there is some self-heating going on but I really don't think that it could make up for a 40-degree differential.

Any insight at all would be great thanks!

There are at least 3 common temperature ranges used for integrated circuits. The most demanding range is the MIL-SPEC range of -55 °C to +125 °C. Parts characterized for that temperature range will command a rather large price premium over the same part that is characterized for the "standard" commercial temperature range of 0 °C to 70 °C. You get what you pay for. The only reason that a part would be characterized for such a temperature range is if the military makes a commitment to buy that part in large quantities. The number of parts characterized for that expanded temperature range is a fairly small subset of all the available parts. IMHO, your only alternative would be to commit to a large purchase of custom manufactured and tested parts.

ETA: There is the Industrial range of -40 °C to +85 °C which might work for you. I did not remember the lower limit when I constructed the original post. The prices will be between the commercial and the MIL-SPEC parts.

ETA2: Checking the datasheet, it appears that the process used to fabricate the part allows it to function over an expanded temperature range on the high side, but not on the low side. I'm not a process engineer, so I'll defer to the folks at TI for a more precise explanation.

 

How much heat would be required to raise the operating temperature of the BUC to 0 °C? You'd be operating on the hairy edge, but that would be better than not operating at all.

 

If the buc is rated to -40, do you trust the manufacturer ?
If it is not as per data sheet, what's the manufacturer say ?
If they have no answer then its money back time and fi days new duc.
Or put a heater on it , with a thermostat !

 

I am grateful for all the responses; it is a great help!

So is if fair to say that any component going into a device that is rated to operate nominally between -40 and +40 degrees C should be also rated at +/- 40 degrees?

I seems hard to imagine this kind of thing being an oversight but who knows. This is a 125V reg and nowhere near those voltages are required.

Not sure if anyone out there has experience with this kind of thing but Im looking for commonalities and behaviors of aging components under cold temps. i.e what happens to a diode, inductor, or cap after 15 years of service when it is exposed to cold temps?

Thanks all!

 

I am grateful for all the responses; it is a great help!

So is if fair to say that any component going into a device that is rated to operate nominally between -40 and +40 degrees C should be also rated at +/- 40 degrees?

I seems hard to imagine this kind of thing being an oversight but who knows. This is a 125V reg and nowhere near those voltages are required.

Not sure if anyone out there has experience with this kind of thing but Im looking for commonalities and behaviors of aging components under cold temps. i.e what happens to a diode, inductor, or cap after 15 years of service when it is exposed to cold temps?

Thanks all!

No
Components in a device are rated to allow the device to work over the data sheet temperature range of the device, not the components in the device.

Simple case , an oven, the oven is rated to work over say 0 to 50 ambient, but inside the components have to work at say 200 degrees.

All you can say is if the device, is rated for -40, the device should work as per data sheet at -40...