Hi,
I am looking for a table to calculate the LM3409HV at 48 V input voltage.
I have the spreadsheet with the two off timers, but it seems that it gives wrong results when using only the standard circuit with one off timer and optional shunt-fet dimming.
Is there another tool?
Best regards
Martin Hermann
Hi, Martin,
Per my understanding, you have input 37.68 as Vo and 40 as Vin, to achieve this, efficiency should be higher than 37,68/40 = 94.2%.(This might be possible) However, you assumed efficiency 88% which is lower than 94.2%. Thus, (1- Vo/(Vin*Eff)）< 0 and negative resistor value got.
Either you underestimated efficiency or input voltage is too close to output voltage and need increase input voltage.
You may simply use equ16 for Roff2 calculation.
Regards,
XG
