AN37
AN37 application note does not provide clear instruction how to select diodes, considering reverse voltage rating.
In particular, will be 200 V reverse votlage diodes sufficient for 220 V AC input voltage +10% -15 % power suppies with LNK302/304-306 family? If not - what reverse voltage rating or peak voltage rating is required for diodes?
Comments
When the LNK turn on, the voltage across the diode is the input voltage. 220Vac means at least 311Vdc, and there is always some spike on the voltage stress. And you may have to pass surge test. That is why AN37 suggest using 600Vdidoe. PLS check the diodes list at the bottom of page 3.
regards
If the electrolytic is charged to +300 V, and if there is a surge of 1 kV at 270 degrees (-1 kV), wont the rectifier diode be seeing -1.3 kV reverse voltage? I'm assuming there is no MOV.
Hi,
Thanks for your inquiry to Power Integrations.
If you can refer to the surge voltage specification, it is a very short voltage spike only; It is not a permanent high voltage. For example if the differential surge voltage is applied on line to neutral, it appears to charge the bus capacitor. So the bus voltage will be increased by limited amount of voltage as the voltage spike is only with short pulse, that has limited power. Depending on the bus capacitance, the maximum voltage on the bus voltage can be determined that will affect the voltage rating of the diode.
Hope this is helpful for you.
When the LNK turn on, the voltage across the diode is the input voltage. 220Vac means at least 311Vdc, and there is always some spike on the voltage stress. And you may have to pass surge test. That is why AN37 suggest using 600Vdidoe. PLS check the diodes list at the bottom of page 3.
regards