LM317 + ceramic cap Q

[woodturner-fran]

A quick Q:

are all LM317 the same? or are there different current ratings?



and ceramic disc caps: does 0u01 mean the same as 0.1uF (seems to me it should be the same as 0.01uF) and if so what are the units or reasoning behind the 0u01?

thanks,

Fran

[SY]

0u01 = 0.01uF. This convention, mostly European, was adopted because of how easy it is to misplace decimal points on reproduced drawings. Likewise 4R7 = 4.7 ohm.

There are several different versions of LM317 with different cases, dissipation ratings, and max currents. The TO3 versions are, not surprisingly, the ones with the highest current and power ratings, the TO92 the lowest, and the TO220 intermediate in power rating, but the same current as the TO3 version. The 338 ups the max current, as does the 350.

There may be some other versions, too, those are just the ones I'm familiar with.

[Shoog]

In the Jung CCS article it mentions that some of the improved LM317's have worse frequency response than the originals. It would be safe to stick with the original unimproved versions.

Shoog

[Circlotron]

Check the ripple rejection in dB for different types of LM317, and also rejection vs frequency. I have had =very= good results with ST ones. As an amplifier they work ok to 40kHz.