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277VAC to 20V using the LNK304

Posted by: joseph.aboueloula on

I am using the LNK304 to design an AC/DC converted.
I see on the datasheet that the LNK304 is rated 85 to 265 VAC.
Can I use it for 277VAC?
Thanks

Comments

Submitted by VCastrellon on 07/21/2011

The LNK304 is not rates 85 to 265 VAC. What it is rated with such voltage is the input of the power supply. The LNK is rated for maximum DRAIN voltage of 700V.
You need to design a transformer to fit your power supply output specification with your input voltage from whatever your minimum voltage (let say 90VAC) to 277VAC. OK?
When you design a transformer you should check the Maximum voltage at the DRAIN node to be below 700 V. let say about 650V under worst conditions.
In order for design your transformer, you can download PI expert from this web site. Go to the top menu, Design Support, PI expert design Software. This is a free program that runs the calculations for you. It tells you an approximated value for maximum DRAIN voltage.

Once you build your transformer you should check with the oscilloscope for DRAIN voltage to be below 7000 volts under worst conditions. What I mean under worst conditions are:
a) turn on the supply at maximum Vin and maximum load.
b) With maximum Vin, apply a load transient, let say from no load to full load.

Submitted by joseph.aboueloula on 07/21/2011

Thank you very much for your quick reply.
And sorry for posting back, I am not sure I understood the difference.
If the main parameter is the DRAIN voltage (700V max)
then why would I need the transformer?
If we apply 277VAC at the input of the power supply we will get a value less then 700V on the Drain, or not?

I am sorry again, but I don't have experience in that field, and I am trying to convince someone that he should not use 277VAC on the input of the power supply.
If you can help me with the explanation I will be thankful.

Thanks a lot