Need help with dc to dc boost converter.

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wynie

Joined Feb 5, 2013
2
Hi all i need help with a dc to dc converter
The configuration is boost the switcher IC is a LM2577
The input source is a 12v 7ah battery
The output is a 30 W led at 32V
Inductor-Panasonic 100uH Ferrite leaded at 2.6A
My problem is the Led is only drawing 0.38A ,the led is giving out 13Watt.
Is the lm2577 capable of delivering1A at 32v continously?
 

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LesJones

Joined Jan 8, 2017
3,571
The LM2577 is going to be running at very near its maximum current rating of 3 amps when the circuit is working. I suspect your problem the the 100 uH inductor. Post a picture of the inductor and the FULL data sheet on it. I suspect the inducter that you are using is saturating and/or it has too much resistance.

Les.
 

spinnaker

Joined Oct 29, 2009
7,835
The LM2577 is going to be running at very near its maximum current rating of 3 amps when the circuit is working. I suspect your problem the the 100 uH inductor. Post a picture of the inductor and the FULL data sheet on it. I suspect the inducter that you are using is saturating and/or it has too much resistance.

Les.

I would also post a picture of the fully assembled circuit. The placement of that coil is critical. I had a heck of a time with this on my first dc to dc convertor project.
 

crutschow

Joined Mar 14, 2008
28,201
Is the lm2577 capable of delivering1A at 32v continously?
It is marginal.
1A@32V output requires an input average of 2.67A@12V.
At this voltage the switcher duty-cycle is about 63% with the peak inductor and switch current being about 3.5A (see LTspice simulation of basic switching circuit below).
This is 0.9A above the maximum inductor current (which likely causes it to saturate).

At a minimum you need an inductor rated ≥4A.

upload_2017-11-20_9-9-56.png
 
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