[alsq]

Has anybody had any luck with this?

http://www.linear-tech.com/pdf/1963fas.pdf

http://www.linear-tech.com/prod/data...?datasheet=886

It's an ornery voltage regulator with excellent specs, that
in any way I tried breadboarding just keeps oscillating.
Grrr

Even if I manage to prevent oscillation for light
loads, as soon as the load increases kaboom. If you have
a project that works, would you share your schematic and
choice of components?

 

[bpribadi]

Did you put small plastic cap 100nF - 1uF for the Adj pin to ground? Try it, put very close to the pin (less than 1/2").

 

[setmenu]

What size cap are you using on output?
I use 4 of these [adjustable versions] in my dac, all small decoupling caps
are surface mount the output capacitance is 10uf and everything is laid out very tightly with all ground paths as low impedance as possible.
But my loads are only up to about 50ma so I can't comment on the effect
of higher ones.


Setmenu

 

[alsq]

Quote:

Originally Posted by setmenu I use 4 of these [adjustable versions] in my dac, all small decoupling caps Setmenu

Can you pls. elaborate?

 

[setmenu]

Quote:

Originally Posted by alsq Can you pls. elaborate?

Rather than elaborate myself, perhaps you would care to show how you are
implementing your regulators?
A schematic/photo, component values etc.

There are many people here with vastly more knowledge than myself , and
if such information were readily available perhaps you would receive some
more comprehensive feedback...


Setmenu

 

[alsq]

This is the circuit with which I had the best luck so far. With a
16 Ohm load at ~14V at the load, there are 5 mV of AC, the bridge
and the regulator are very hot, and the trace on the scope is
fuzzy, sometimes I do get a sync, others I don't. The prototype
is loosely breadborded (i.e. not a tight or particularly clean assembly).
Values of components happen to be what I had laying around . . ..

 

[setmenu]

Oops! I made a mistake, I use LT 1963,s in my application not 1962s

Anyhow regarding your schematic , every thing seems fine..except I see you appear to have coupled your ADJ pin to ground through the 0.1uf cap?
I have found no reference to this in the data sheet?

Setmenu

 

[alsq]

If I remove it, AC at load goes from 5mV to 30mV (approx). Sigh. It also looks OK to me, but not to the LT1963, apparently.

 

[Whit]

Try taking out both the .1uf polyester and 10nF ceramic that are on the output of the regulator. I believe that the esr of this combination is too high for the regulator to handle. Small value ceramics have high impedance at lower frequencies so I believe this is what is giving you grief. I suspect the addition of the .1uf polyester lowers the esr and makes the regulator more stable.