Re: gEDA-user: Alarm clocks and switching regulators

[John Griessen <john@xxxxxxxxxxxxxx>]

Randall Nortman wrote:

> I am dropping anywhere from 20V to 42V (peak) down to 3.3V. 


  it has occured to me to just accept a bigger 120Hz ripple
> and use smaller bulk caps.

Sure.  That's a good direction to explore.  Figure the absolute value you need
and keep it above that  by knowing how much your current draws are.
Let the switcher input see  5 to 42 Volts and its constant inductor current mode
will have to exercise some, and you can help it filter out ripple with attention
to grounds and guard voltage zones in your layout.

Keep all that primary side switching off to one side.

John G
-- 
Ecosensory   Austin TX



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