I have some questions about ADUM3070.
Since I don't have experience using isolated DC/DC,
It would be great if anyone could give me some advice.
(sorry to ask many questions at the same time)
I'm trying to calculate Transform ratio by using the following formula
But I don't know what duty cycle should be.
it says Duty should be 0.3, but I dont where this number come from.
Please advise me on how to estimate duty cycle.
In order to select Trans inductance, Cout and L1 inductor,
Are there any calculating formulas?
The datasheet recommend value like 400uH for Trans, 47uF for Cout and 100uH/400uH for L1.
Should I use these figures?
Since the output current for my model could be less than 10mA so I'd like to use the smaller capacitor and inductor.
The datasheet says that it's okay to use 5V to 3.3V for Ns/Np=2.
But I don't think Ns/Np is calculated in 1.2 for 5V to 3.3 V.
Could you make sure if it's correct?
[From page 15]
For a similar 3.3 V input to 3.3 V output, isolated single power
supply and with V DD1 (MIN) = 3.0 V, the turns ratio is also N S /N P =
- 2. Therefore, the same transformer turns ratio N S /N P = 2 can be
used for the three single power applications (5 V to 5 V, 5 V to
- 3.3 V, and 3.3 V to 3.3 V).
It looks like the most low power isolated DC/DC incorporate Fryback converter.
But ADUM3070 is push-pull converter(using two FET inside the IC).
I think Flyback can reduce external components like Inductor on the second side.
So I just wonder what is the merit of push-pull converter for the low power isolated DC/DC.