- - max power dissipated by the snubber resistor
- - snubber resistor
- - snubber capacitor
- - switching period
- - switching frequency
- - Input voltage to the converter
- - transistor max acceptable voltage
- - average input current
- - magnetizing inductance of the transformer
- - leakage inductance of the transformer
- - transistor peak voltage, spec from datasheet
- Leakage inductance
It is not easy to calculate the leakage inductance of a transformer, but it can be measured after the transformer is built, or if a prebuilt transformer is used, it can be obtained from a datasheet. It can be assumed that the leakage inductance is 3% of the magnetizing inductance, .
If a transformer is well designed, leakage inductance can be reduced to 1% of the magnetizing inductance.
- Snubber resistor
To calculate the snubber resistance, , an acceptable max transistor voltage, . You want to select a that has a wide margin from the peak transistor voltage rating specified in its datasheet. It still must be greater than the transistors blocking voltage,
Using this, you can calculate , and
- Snubber capacitor
- Snubber diode
The diode voltage must be able to block voltage a high voltage, 1N4007 tends to work.
Flyback using the following specifications:
If you choose to use a schottky diode its a good idea to have a snubber.
- design to be added