PWM controller, 0-100%, external VREF?

Feb 03, 2008 4 Replies
R

Hi,



I'm trying to find what I thought would be very simple:



A PWM controller that can do 0-100% Duty Cycle and has an error amp WITHOUT VREF connected (i.e. I can supply VREF). I've checked every major supplier up and down with no luck.



I can get around current-mode control by summing OSC ramp with current comparator.



Something like SG1524 that does 0-100% duty cycle would be perfect. Any suggestions?



Rob.



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J

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going with something like that, you can mod it to your wishes. That package has an extra op-amp left of to use as an error amp if you wish..

Don't know what your application is but this does work well. it'll do 0..100% duty with no problem.

http://webpages.charter.net/jamie_5"
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T

Um, LM393?

OK, so it takes four more resistors than a PWM-in-a-box, so what.

Tim

-- Deep Fryer: A very philosophical monk. Website @

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R

Tim,

I should have probably specified, looking for PWM frequency of 400 kHz+

Rob.

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T

Ah, okay then. LM319. :^)

Might take up a bit of space / current though..

Tim

-- Deep Fryer: A very philosophical monk. Website @

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current

Any

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