[time-nuts] Which voltage regulator chips offer good performance...?

Bob Camp lists at rtty.us
Mon Apr 26 12:51:34 EDT 2010


Hi

Two examples:

Linear LT1764 ($4 to $8 depending on qty):

Low drop out, low self generated noise, lots of power, lots of current.
Needs help past ~ 8 KHz for crud rejection. 

Linear LT1963 ($3 to $5 depending on qty):

Better crud rejection, higher dropout, lower power, lower current. Needs
help past ~ 100 KHz. 

Both are adjustable parts. You can tailor them to match the supply you have.

My preference is the first part with a nice coil (or better two) in front of
it. There are a lot of parts designed for switchers that will do a fine job.
Since the regulator needs at least 10 uF in front of it, the coil(s) can be
in <= 2 mHy and do fine. I get my coils on the e place so I can't recommend
a specific part. You can also do just fine ripping them out of dead
switching supplies. 

One thing you could do if cost is no object - cascade several of the parts
with a bit under a volt across each one. +15 volts to +12 volts with three
stages of isolation. Provided ground loops don't get you, there won't be
much line related stuff at the output of that cascade.

Bob


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Michael Baker
Sent: Monday, April 26, 2010 11:02 AM
To: time-nuts at febo.com
Subject: [time-nuts] Which voltage regulator chips offer good
performance...?

Hello, Time-Nutters--

Bob Camp said:

 > snip
 > ...stability is not the only issue.
 > Crud on the power supply is an issue as well.
 > Some of the ultra low drop out regulators
 > are not real good crud blockers.
-----------------------------------------------

So... This would seem to bring up the question
of which 3-terminal regulators ARE good (if not
"good" then which are the "best"?) providing both
stability -AND- clean, crud free output? 

How about old standby regulators such as
the 723?  Problem there is that the stand-alone
chip is only good for really low current.

For years I have been using general purpose
3-terminal regulators sometimes with carefully
selected low impedance capacitance on the output.
 
In some cases I have found that a high-gain
transistor in the output configured as a
"capacitance multiplier" serves to handle
current load spikes but is only a nominal help
in cleaning up crud on the output.

Comments?  Suggestions? 

Mike Baker
-------------------------------------

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