AW: Power Supply Sequencing?

Haible Juergen Juergen.Haible at nbgm.siemens.de
Fri Jan 30 15:05:29 CET 1998


	>Has anybody out there had problems with power supply sequencing
in a
	>modular (ASM-1, other homebrew, etc.)?

Yes - I think I wrote about this on DIY before. In short, it was like
this:

My JH-3 Modular uses a central +/-18V supply, plus +/-15V on-board
regulation for each module.
The +/-18V is divided into 3 branches, with 3x 7818 and 3x 7918
regulators.
For the modules, at first I wanted to use 7815 and 7915 regulators
on-board regulation. But for some reason, some (not all) of the
negative regulators (7915) locked at power-up, especially when
I switched the System off and on again after a short time. I tried
backward
diodes at all possible locations, but the problem partly remained.
Finally, I used the dual tracking regulator (RC4195) for the +/-15V
on-board
regulation, and since then everything is fine. For low current (<100mA)
+/-15V regulation I haven't found anything better. The 4195 works as
good as two 723's, and you have a dual regulator in a tiny 8pin DIL
package.
You're stuck to +/-15V, of course.

JH. 





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