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LM3429 flashing LED driver?

eem2am

Aug 3, 2009
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We are doing a ~2Hz flashing LED driver

vin=12v
vout= ~33v (max)
iled = 0.45 (bit this is in the on state, oviously zero in off state)
buckboost
926khz

We use LM3429 controller.

We are flashing the leds and want them to come back on smoothly each time.

Can we do this by shorting the comp pin to ground temporarily before flashing the leds back on?

LM3429:
http://www.ti.com/general/docs/lit/getlite...29&fileType=pdf
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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What do you mean by "come on smoothly"?

I doubt that shorting the pins of a comparator to ground is a good idea.

Your link is broken.
 

eem2am

Aug 3, 2009
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by coming on smoothly i mean no over shooting in the inductor current.

For example, shorting the comp pin of the ucc28c43 to ground affects a soft start, ...is it the same with the LM3429.

For the ucc28c43, adding a soft start circuit is done via the comp pin, as many of the old unitrode app notes testify
 

Harald Kapp

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Have a look at the LM3429's datasheet.
Figure 5 shows an anlog dimmming circuit. You can use this to simulate a soft start. Read also the text, it describes various dimming methods.
 
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