LT1463

Hi:  At Linear Technology the note " designed, characterized and expected to meet these extended temperature limits,

but are not tested at –40°C and 85°C" was fairly common.  It meant that, although the part was designed and characterized

for -40C to +85C, we did not production test and guarantee to those temperatures.  Rather, the part was released as a simple

C grade and production tests were only set up for 0C and 70C tests.  Production tests at 25C are applied on 100% of production.  

Temperature tests are performed on a sample basis (usually 1000 parts per lot), and if one failure then the entire lot is tested at

100% over temperature.  It was by the 25C and temperature tests that LT established the "guarantee".  So, because the 

extended temperature tests were not implemented, we do not guarantee to those limits.

If the demand for a guaranteed I grade were high enough (say >50k units) then LT would have considered establishing the extended 

temperature flow.  However, this would of course be at the company's discretion given the available resources to dedicate to the project.

By the way, if you look at the temperature curves in the data sheet, you'll see several extending to I grade limits and even to military grade

limits.  We just don't have any production tests beyond the 0C and 70C limits.