I know I asked this question before ... and I see others have but after a night of reading, I am still confused.

I need to replace a NE555N which is now obsolete.

OK ... I just looked over a handful of data sheets .... read a dozen posts ... and am more confused than ever.

The NE555N is obsolete.

Digikey lists ....

"upgrade" ... NA555P, SA555P

"similar" .... NE555P, SE555P


From what I can see ... NA, NE and SA are 4.5 to 16 volts ... SE 4.5 to 18

NA -40 to 105
NE 0 to 70
SA -40 to 85
SE -55 to 125


What does the N vs P at the end of the part number mean? Package?

If there is not "real" difference, then why not use the SE555P ... it seems to have "better" specs.

Why do they even make so many versions.

Thanks!

 

From the TI forums:

"NA, NE, SA, SE are different from each other in just the temperature range. SE has the widest temperature range, higher VCC and is the only version that has electrical characteristics with temperature limits.

All 4 are functionally the same."

 

Why do they even make so many versions.

For one thing, parts with a narrower temperature range generally cost less. Why pay more for a part that does what you don't need?

 

From the TI forums:

"NA, NE, SA, SE are different from each other in just the temperature range. SE has the widest temperature range, higher VCC and is the only version that has electrical characteristics with temperature limits.

All 4 are functionally the same."

Awesome ... since I only need a few, price does not come into play. My "gut feel" was to use the SE just because it seemed to have wider (in my mind this means better) specifications. I just wanted to make sure I was not overlooking something important. Thanks.

 

For one thing, parts with a narrower temperature range generally cost less. Why pay more for a part that does what you don't need?

Since I only need a few, price is not important to me. I just wanted to make sure I was not missing anything .. thanks

 

That "wider spread"in the variables range is because of LOOSER tolerances. Wider variability in the specifications. The expensive ones meet all specs over the whole military temperature range. And often they are 100% tested. That is why folks buy any old "555" timer IC and adjust the resistors for the performance they need.