I need 15 volts regulator from 40 volts DC

[BrianDonegan]

It definitely does not feed higher than the set output voltage during startup or shutdown. It would make it a pretty ****-poor component if it did.

 

[sofaspud]

Well, now that is an issue. With some applications NS does advise a "kickback" diode across the reg. To shunt capacitor voltage and prevent it bleeding into the output. I believe this is true for all the 317/78xx regs. But it has nothing to do with previous posts.

 

[BrianDonegan]

I thought that is what you referring to with the term "lag."

I will also add, that the LM317/337 have much better noise performance than LM78xx regs.

 

[sofaspud]

I thought that is what you referring to with the term "lag."

Post #20 referred to the output lagging the input 0 to V+. Post #22 referred to the output lagging the input V+ to 0. I guess we'll drop the other false alarms.