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how the Vds of TNY267 calculated, how primary inductance calculated

Posted by: hemanth on

i have seen Vds of TNY267 is taken as 4.41 but in the datasheet i have didnt got this information

how primary nominal inductance calculated

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Submitted by PI-TOMMY BRADFORD on 04/10/2022

Greetings hemanth,

Thank you for using our device.

May I ask where do you see this 4.41 Vds of TNY267? I am just curious because typically the value of Vds is around 500 V to 600 V.

The formula of Vds for a typical flyback topology is Maximum DC input voltage + VOR (reflected output voltage) + the voltage caused by the leakage energy.

For TinySwitch device family, the formula of primary inductance can be found in page 45 for continuous conduction mode and page 49 for discontinuous conduction mode in the application note of TinySwitch-3 (an-90_tinyswitch-iii_family_design_guide.pdf (power.com)). 

 

I also noticed that you are using an old version of TinySwitch family, I want to suggest the latest version of TinySwitch which is the TinySwitch-4. It has lower no load power consumption than the old version for example. If you want to check it out, here is the link of the datasheet of TinySwitch4 (tinyswitch-4_family_datasheet.pdf (power.com))

TinySwitch-4 is also in the PI Expert Online (PI Expert | Power Integrations, Inc.) where the values like the Vds and primary inductance is automatically computed.

Feel free to contact us if you have any further questions.