Power Supply TNY263

Posted by: Reiner on 04/30/2010

Hi,

we have designed attached power supply with TNY263. Without load we have measured on AC-Line about 29mA which results in a power consumption of 6.6W with no load! How can we reduce the no load power consumption

Best regards
Reiner

Files

PowerSupply.pdf (16.34 KB)

Comments

Please check the board for component values... probably a smaller voltage zener was stuffed instead. Assuming that the transformer is designed properly, the schematic shows nothing that would point to higher no load consumption.
I will say however that L2 and C2 are very aggressive. Their resonant frequency should be around 10 kHz

Thanks you for your answer.
But L2, C2 are not assembled and so we measure the no load consumption.
We use Myra Transformer 74074. Attached you will find the datasheet on page 11. Would you please be so kind and check this transfomer?

The zenerdiode is 3V9 is this correct for the transformer?

Thanks and best regards

Transformer if wound correctly should be ok.
So how do you say that no load consumption is 6 W? Are you simply multiplying 29 mA * 220 V? If so then this is incorrect. The 29 mA is RMS current and will be mainly reactive power...
Use a power meter that measures real power to determine input power. Another way to look at it is that if 6 W are being consumed at no load then the TNY263 will heatup significantly at no load. Is this the case?

You are right, it is reactive power. We measured the temperature and we think we have a problem with the EMC PI-Filter (C18, L2, C19, L4). The temperature of tny263 is ok. What paramters should the pi-filter have (low ESR and so on)?
Thank you

the right part numbers of pi-filter are C4, L1, C5, L3