UC3842 symmetric

Fernando Cuzziol30

Prodigy 80 points

Other Parts Discussed in Thread: UC3843

I already have a source SMPS using this component that meets my needs. X 12V 6A. Photo attached.

Now I'm developing a smps with symmetrical output +/- 35V x 3A for audio and +/- 15V x 500mA for pre-amplifier.

In test, added the winding isolated symmetrical output and the feedback reference was between 12V.

There is another way to proceed for feedback ???

I look

over 10 years ago

0 John Griffin1 over 10 years ago

TI__Mastermind 34465 points

Not sure what the problem is. Do you have a schematic of the circuit?

0 Fernando Cuzziol30 over 10 years ago in reply to John Griffin1

Prodigy 80 points

I providanciar and sent in sequence

0 Fernando Cuzziol30 over 10 years ago in reply to Fernando Cuzziol30

Prodigy 80 points

John,
We were on vacation and just returned this week.
How had asked annexed the smps scheme using the UC3843.
I look back with modifications.

0 Fernando Cuzziol30 over 10 years ago in reply to Fernando Cuzziol30

Prodigy 80 points

John.
What I want to know is how is the feedback loop for a controlled symmetrical output. Today I have a 12V output only to control the system. There would be how to direct control in symmetrical line ????

0 John Griffin1 over 10 years ago in reply to Fernando Cuzziol30

TI__Mastermind 34465 points

Fernando,
I assume the +12V output is the output connected to the optocoupler.
This continues to control the switching of the UC383843. The +15V and -15V rails are controlled are controlled with the linear regulators 7815 and 7915. This is a very common method of controlling a multi output power supply.

John

0 Fernando Cuzziol30 over 10 years ago in reply to John Griffin1

Prodigy 80 points

ok.
Now about the "zeros". I have 3 zeros, the entrance, the coupler feedback and symmetrical.
The input and the feedback I engage by a capacitor 1nF x 1KV.
The zero of the symmetrical output as engage ???

0 John Griffin1 over 10 years ago in reply to Fernando Cuzziol30

TI__Mastermind 34465 points

Sorry Fernando,

That question went way over my head.

Can you simplify ?

John

0 TI^^ADi over 10 years ago in reply to Fernando Cuzziol30

Prodigy 20 points

I want know how do you setting your CM core parameters ，do you have spetrum analyser so you can pick up noise in your circuit，or you made it in experience。In addition ，UC3843 its duty cycle can reach 99% so why not add a slope compensation to it prevent sub-harmonic oscillations

0 John Griffin1 over 10 years ago in reply to TI^^ADi

TI__Mastermind 34465 points

For answer to these questions please refer to

http://focus.ti.com/docs/training/catalog/events/event.jhtml?sku=SEM401001&DCMP=hpa_contributed_articles&HQS=ArticleReprint+OT+2003powerseminar-ca

These old seminar papers are your best source for answers to current mode control and the compensation methods.

0 Fernando Cuzziol30 over 10 years ago in reply to John Griffin1

Prodigy 80 points

I have 3 isolated zeros, as shown in the diagram. How interconnected to not cause noise in audio.????

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UC3842 symmetric