I would like to ask you two questions about the LM34927.
Question ①
See No. 8.2.1.2.1 on page 17 of the data sheet
"If the secondary (isolated) output voltage is significantly higher or lower than the primary output voltage, a turns
ratio less than or greater than 1 is recommended. The primary output voltage is normally selected based on the
input voltage range such that the duty cycle of the converter does not exceed 50% at the minimum input voltage.
This condition is satisfied if VOUT1 < VIN_MIN / 2."
Is there a description, why? And what happens when it exceeds 50%?
Question ②
Older version datasheet (SNVS799A-APRIL 2012-REVISED NOVEMBER 2012)
fsw = Vout / (10 ^ -10 × Ron)
However, the latest new version of the data sheet (SNVS799H – APRIL 2012 – REVISED NOVEMBER 2017) says
fsw = Vout / (K × Ron) K = 9 × 10 ^ -11
It is described as. Why is it different?
Thank you for your reply.