UC 3846 current mode control IC help

jegandren · 19th June 2008, 03:57 PM

hi,

im just studying on using UC 3846 as my SMPS control ic... i have tried conecting an open loop test circuit....but the it looks like there is no output pulse given to drive the switch of the trasistor...is there anyway to test the UC3846 current control IC. newbie here please help!!!

(any replies regarding this would be appreciated)

ifrythings · 21st June 2008, 06:18 PM

check out this http://focus.ti.com/docs/prod/folders/print/uc3846.html

go close to the bottom and there is a section called application notes, go through those and see if that helps you.

jtkraj · 24th June 2008, 01:57 PM

These devices are Current controlled. you have to provide a Current sense resistor and fead back circuit.

Each cycle have to be controlled through these signals.

check you have configured the comp signal properly.

switchmodepower · 1st July 2008, 04:41 PM

Make sure that the comp pin is high, shutdown is low, make sure CL pin is set. You can also add a slope comp circuit to get some sort of ramp on the curr feedback pin- (this also helps with noise immunity)

App note..
http://www.ti.com/litv/pdf/slua075

19th June 2008, 03:57 PM	#1
jegandren diyAudio Member Join Date: Feb 2008	UC 3846 current mode control IC help hi, im just studying on using UC 3846 as my SMPS control ic... i have tried conecting an open loop test circuit....but the it looks like there is no output pulse given to drive the switch of the trasistor...is there anyway to test the UC3846 current control IC. newbie here please help!!! (any replies regarding this would be appreciated)

1st July 2008, 04:41 PM	#4
switchmodepower diyAudio Member Join Date: May 2007	Make sure that the comp pin is high, shutdown is low, make sure CL pin is set. You can also add a slope comp circuit to get some sort of ramp on the curr feedback pin- (this also helps with noise immunity) App note.. http://www.ti.com/litv/pdf/slua075 __________________ http://www.switchmodepowersupply.net

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21st June 2008, 06:18 PM	#2
ifrythings diyAudio Member Join Date: Oct 2005	check out this http://focus.ti.com/docs/prod/folders/print/uc3846.html go close to the bottom and there is a section called application notes, go through those and see if that helps you.

24th June 2008, 01:57 PM	#3
jtkraj diyAudio Member Join Date: Jun 2008	These devices are Current controlled. you have to provide a Current sense resistor and fead back circuit. Each cycle have to be controlled through these signals. check you have configured the comp signal properly.

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