Do you know about intelligently controlled active clamp flyback?

What is Smart Control Active Clamp Flyback? What does it do? When I first started cooking, I preferred to be alone and thought other people in the kitchen would be a distraction. But as I started trying more complex recipes with multiple cooking steps, I found having a helper was very helpful and made the cooking experience more fun. As the saying goes: If you can't beat 'em, join 'em.

The same principle applies to active clamp flyback.

Everyone wants smaller AC/DC converters, especially when they are used in phone or tablet chargers. Due to its simplicity, the flyback converter is the preferred topology as it can efficiently convert AC power to DC power with only few components. However, there is a limit to how small a flyback circuit can be because losses associated with transformer leakage inductance limit practical size. Every design so far has dealt with this by reducing leakage inductance. But active clamp flyback breaks this cycle.

Figure 1: Active clamp flyback, leakage inductance in red, active clamp in blue

Active clamps store energy and transfer it to the output rather than dissipating it in a resistor-capacitor-diode (RCD) or Zener clamp to deal with leakage inductance. Smart control clamps also provide zero voltage switching. This eliminates two major sources of loss, resulting in a significant reduction in size. If you want to use gallium nitride (GaN) field-effect transistors (FETs), which have lower output capacitance and on-resistance, the size of the adapter can be halved!

But the devil is in the details, because if active clamping isn't intelligently controlled, it can actually make efficiency worse. Active-clamp flyback was only a fantasy in the past because there were not enough smart controllers to implement this topology. But this phenomenon has changed in UCC28780.

This active-clamp flyback controller is specifically designed for use with silicon (Si) or GaN-based power stages, making this topology suitable for any design. The UCC24612 synchronous rectifier complies with U.S. Department of Energy (DoE) Class VI or Code of Conduct (CoC) Tier 2 standards. The above is the analysis of intelligent control active clamp flyback, I hope it can help you.