sg3532j psu - Page 1
Forum section: electronics / projects

author: m3vuv
author_rank: Super Contributor
timestamp: December 15, 2018, 02:50:05 pm
content: Hi all,im looking for some help,i was going to try and build a psu using a lm723,instead i just brought a sg3532j ic,it looks better as the current sense needs only 80mv as oposed to the 600mv of the 72,the issue i have is i cant find a schematic,any ideas?,cheers m3vuv.

author: m3vuv
author_rank: Super Contributor
timestamp: December 15, 2018, 04:12:43 pm
content: I was just looking,would the attached schematic work if i played with the current sense resistor values to suit?,looking at the datasheets for the 723 ic and the sg ic the pinouts are pretty much identicle!. regards m3vuv,ps the sg chip was quite expensive so dont want to fry it!

author: m3vuv
author_rank: Super Contributor
timestamp: December 15, 2018, 05:21:08 pm
content: well to give you a clearer pic of what i have and am trying to do,i have 10x 2n3773 pass transistors to use in place of the 3055's also a mc342p over voltage ic,the crowbar part etc is no probs,ive used the schematic i posted in the last thread before and had r8 switched between 120 ohm and 10k,that gave me 2 ranges going from about 3v low to about 28v high,in that one i used 6x pass transistors,the current foldback range didnt start untill about 5 amps,the 723 needs .6v to go into current foldback,the sg 80mv,im trying to build a psu that goes from about 3v to 30v say in 2 ranges and current limits from say 300ma to 30a,againe in say a high and low range,basicaly using the cct attached but with my own mods to it and using the sg ic,i see no reason why its not doable,my transfo is good for about 60a and my bridge rectifier is good for 180a,regards m3vuv.

author: m3vuv
author_rank: Super Contributor
timestamp: December 16, 2018, 05:55:19 pm
content: didnt realise i was asking the imposible!,im supprised!!

author: David Hess
author_rank: Super Contributor
timestamp: December 17, 2018, 04:21:00 am
content: The SG3532 is an improved LM723 but not a drop in replacement.

author: quadzillatech
author_rank: Contributor
timestamp: December 17, 2018, 10:22:12 am
content: Hi,im m3vuv,had to redo the account as couldnt log in,in answer to your reply,im aware the sg ic isnt a drop in replacement,that is the whole point of my post ffs!,I need to know what the differences are apart from the current foldback,ie what has to be altered in the scematic i posted to make it compatible with the sg ic,is that plain enough!!,i feel im just wasting my time!

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: December 17, 2018, 11:40:08 pm
content: Hi M3VUV,The SG3532 is an old part, that was made in various package. It is essentially obsolete. I don't know when it became obsolete.If I check on findchips.com:https://www.findchips.com/search/sg3532I don't find any new inventory.(This also means any parts on eBay are likely to be fake)Even if you had some good SG3532, you are unlikely to generate much interest in your project because nobody can reproduce the circuit.I would stick with the 723.Regards,Jay_Diddy_B

author: quadzillatech
author_rank: Contributor
timestamp: December 18, 2018, 11:15:51 pm
content: Well an update,didnt manage to get the sg ic to work,i expect its a fake,ive a lm334z,is there any way i can use that with the 723 so it can be a cc psu,also adjustable?,cheers Paul m3vuv.