Operating at >100 deg C

Mark M · Guest

Hi,
Does anybody has any experience with running PIC 16F876 I/P at temperatures > 100 deg C and <130 deg C?
Data sheet implies it can be done but all parameters are spec'ed for temperatures between -40 and +85 deg C. I think RC osc is out of question as internal OSC will drift too much, so crystal ( hi temp ? ) or ceramic osc?

Mark M.

Guest · Posted: Tue Sep 28, 2004 12:14 am

Crystal. But could you pull off your PIC board out from boiling water?

Mark M · Guest

Not without gloves. But environmental chamber can cool it off for safe touching. I don't think pulling it out matters that much. Important for me is if PIC will still work at high temperatures.

Mark M.

arun · Guest

Hi,

No it does'nt work.

We tried to run a datalogger system which had a PIC 16F877 ; at around 60-70 degC , but it went haywire, it was unable to write to a external EEPROM, also had trouble communicating through RS 232.

Maybe you should design a thermal proofed unit so it is well protected from high temperatures, also you could go in for MIL grade instead of the standard commercial ones.

thanks
arun

Ttelmah · Guest

Haplo · Joined: 06 Sep 2003 Posts: 659 Location: Sydney, Australia

Ttelmah · Guest

Mark M · Guest

I checked with Microchip and data sheet says that the E version is spec'd for up to 125 C operating temp. but it won't work off 3 - 4.5VDC and we are using a 3 x 1.5V battery. This going to be another problem. I have to ask Ttelmah, if he could hint me on batteries that will operate at temps > 100C.

Another "murky" thing is that in the MCP data sheet the LF876 part is spec'd as operational at bias up to 125 deg C but parameters at elevated temperatures are specified only for "E - extended" grade parts. The LF parts don't carry "E" suffix. Since our device has to run down to 3VDC and E part needs at least 4.0V, it looks like we have to redesign our device to have 6V battery with 4.5V or so regulator. I was thinking that just getting better parts will do withour redesigning.

Do you, guys know in MCP makes mil spec PIC's?

Mark M.

Ttelmah · Guest

Try 'Electrochem'. They did Lithium batteries in glass fibre cases rated to 200C!...

Best Wishes

Guest · Posted: Thu Sep 30, 2004 5:32 pm

Mark M · Guest

Thank you all very much. You have been very helpful.

Mark M.

Will Reeve · Joined: 30 Oct 2003 Posts: 209 Location: Norfolk, England

I’m using a MAX682 in two current designs and they work very well. Both devices run off 3 x AA batteries. One Alkaline the other NiMH, so 4.5v and 3.6v in respectively. Only external components are three capacitors. I use 0805 size chip ceramic capacitors which will handle 125deg (amazingly you can get 10uF in this package size!). The IC only does +85deg so you might have to talk to Maxim about 100degC operation!

Keep well,

Will