VIPER319-HD AC/DC Design

[tensaisakuragi06]

Hello friends, i design  ac/dc converter circuit using VIPER-319HD with eDesignSuite. One point makes me confused. In attached document, i am not sure these points are GND or not. When i look the datasheet, it seems that these points are related with GND but i am not sure about that. Can you clarify my doubts? Thanks all for your efforts.

[AScha.3 · Accepted solution]

NO GND !!!

These point are to be connected together and to the "gnd" and "ovp" pin of the chip.

NEVER to input or circuit ground ! (It has a different symbol also.)

But you know : this circuit has NO safety , its direct connected to mains ; so whole circuit has to be mounted isolated and enclosed, so nobody can touch it, including the "12 V out" !!!!!

So if  you are not familiar with safety rules and working with mains voltage levels :

DO NOT BUILD THIS !!!!!

[tensaisakuragi06]

Thank you for your advice and reminder. I appreciate your thoughts.

[tensaisakuragi06]

Thank you for your advice. I know about the non-isolated situation. I also want to know that(if possible), can this circuit stably supply the 500mA(max). current with the 15-265VAC input? Theoretically i design this circuit but no idea about that. Some of my components are still waiting for delivery, so i can not simulate this circuit in reality.

[AScha.3]

Ok, so you know : any testing only with an safety isolation transformer , to separate from mains.

About the 500mA : i dont think so ; its on the limits for a no transformer circuit :

Current goes 100% through the viper ....and these chips are famous --- to blow up some day. 🙂

So for 500mA better use a flyback transformer, then no problem.

That's just my opinion.

[tensaisakuragi06]

Only problem is that wide range of  input. Reaaly hard to find a transformer in these range. tahnk you for your kind opinion 🙂

[Andrea Francesco MERELLO]

Hallo

The highlighted points (gnd triangular empty symbol) are the 'device' GND. They are NOT to be connected with the board Gnd which is represented by striped gnd symbol.

Actually the highlighted gnds have to be  connected in a floating local gnd copper  pour, as small as possible, but still underneath all the other discrete components tied to the same reference like Cc Rc Cvdd and so on. 

Keep in mind that the bigger is the overall layout of those floating parts, the more issues you will have with EMC, which is common to the floating buck topology. So pay attention to the layout rules. 

Take reference from ST demo boards.