Used for: Isolated supplies where switch voltage must be limited and where 50% duty cycle max is acceptable
Pros:
- Switch voltage stress is clamped to Vcc
- Leakage inductance energy is returned to the supply
- No snubber needed
- Transformer primary connections swing symmetrically -
can can cancel EMI if mechanical layout considered
Cons:
- Two switches needed
- High-
side gate drive needed - Duty cycle limited to 50%
Basics:
- Same as forward converter except two transistors switch the transformer primary
- Each end of the transformer pri alternately goes to supply and 0V
- This means each transistor has voltage limited to supply rail max
- This in turn limits reset voltage to supply
- This in turn limits duty cycle to 50%
- V0 = VinD . Nsec/Npri