InnoSwitch3-EP

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I used the formula to calculate the transformer: https://techweb.rohm.com/knowledge/acdc/acdc_pwm/acdc_pwm01/940/#p02
however there is a difference between my calculation and pi expert online.

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calculation.zip83.42 KB

Hi Lupinn, Thank you for the question. There are 2 reasons for the differences.

 

On a first look there are some differences in the initial data for both designs from xls and PIxls you provided. Switching Frequency - 70 / 90 kHz, VOR - 85 / 65V, core is close but different.

 

The main reason is the methodology.

 

The one you are comparing with is related to fixed frequency variable current limit operation. InnoSwitch family products are employing both variable frequency and variable current limit. For Steady State, full load design point you better consider variable frequency, fixed current limit design methodology. That is what PIxls is using. Best Regards,