Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!mintaka!ai-lab!mbeck@ai.mit.edu
From: mbeck@ai.mit.edu (Mark Becker)
Newsgroups: sci.electronics
Subject: Need help with switching regulator
Keywords: Power supplies PWM switching regulators
Message-ID: <12185@life.ai.mit.edu>
Date: 4 Dec 90 14:48:47 GMT
Sender: news@ai.mit.edu
Followup-To: sci.electronics
Lines: 21

Hello *

I'm trying to work up a design for a PWM switching regulator using a
TL-594 IC.  +12 to -13.6, 750 mA, f(osc) about 110 KHz.

So far I've got it generating -13.6 from +12 at about 30 milliamps
That works fine.  Attaching a 20 ohm resistor for a test load causes
the converter to draw enough current to shut down my bench supply
(about 3 amps!).

I've measured the current through the flyback inductor (.1 ohm series
resistor to measure the voltage drop) and there is no sign of
saturation; the curve is nicely linear while the +12V is switched ON.

I would appreciate hearing from people with suggestions regarding PWM
regulator design.  I'm trying to replace a constant-ON-time regulator
(TL-497) with a TL-594 PWM to get the sound generated by the inductor
out of the range of human hearing.

Mark
mbeck@ai.mit.edu	-or-	mbmm!mbeck@talcott.harvard.edu


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