🚀 go-pugleaf

Using 3-terminal regulators for high voltage regulating circuits by
referencing the "ground" leg to something other than zero volts is
tricky.  The problem is making sure that none of the voltages
appearing between the leads of the 3-terminal regulator at
power-up or power-down exceed the manufacturers' recommended
ratings.

3-terminal regulators a la 78xx series get very angry if the load
side voltage exceeds the input side voltage by much (relative to
the ground pin).  The first line of defense is to put a reverse
biased rectifier diode across the input and output.  This prevents
blowing the regulator at power-down if you have a lot of
capacitance on the output side.  It is a good idea to use a
protection diode even if you aren't lifting the ground terminal.

If you are trying to regulate a 60 volt supply, the outboard
components to protect the 3-terminal regulator are going to begin
to become complex.  It would probably be just as easy to use
discrete components for the pass elements.


-- 
Bill Mayhew      NEOUCOM Computer Services Department
Rootstown, OH  44272-9995  USA    phone: 216-325-2511
wtm@uhura.neoucom.edu   (140.220.1.1)