High Efficiency and High Power Density AC/DC Adapters with PD 3.0

PD 3.0 (Power Delivery 3.0) adapter is a type of USB-C charger that can deliver power levels to devices, up to 100W, 20V@ 3A, using the latest USB PD standard. It allows for faster charging and powering of various devices, including laptops and phones.

The flyback topology is one of the most used circuit topologies in the field of power conversion, especially in lower to medium power applications (such as AC-DC adapters, for example). The reason for such a high level of utilization of the flyback topology is rooted in its simplicity and low cost of implementation, as well as in the fact that it can operate efficiency over a very large range of input voltage. The AC-DC adapters with power under 70W, to gain the capability of operating all over the world, requires an operation from an alternating input voltage ranging from 90Vac to 264Vac, a total range of 3:1.

In addition to that, the new PD 3.0 standard for power delivery requires that the AC-DC adapters provide an output voltage ranging from 3.3V to 20V which is a range of 6:1.

Rompower developed “Ideal Flyback” topology which is based on a standard QR Flyback wherein the leakage inductance energy is harvested in a very simple way by the use of a passive clamp and the harvested energy is used to obtain ZVS on the switching elements. Using Rompower technologies there are no spikes nor ringing on the switching elements in any operating conditions. These novel technologies apply to any power level under PD 3.0. Rompower developed mature designs for 65W and for 100W and for other power levels designs can be provided on request.

Rompower 65W AC/DC Adapters

In Figure 1 the efficiency of the Rompower 65W AC/DC adapter is presented versus the best competitors on the market. The efficiency gain of Rompower’ s adapter averages is due to Rompower technologies.

Rompower Technology Advantage in Reaching the Best World Performances for AC/DC adapters as depicted in Figure 1.

The significant gain in efficiency over the competition is due to seral key Rompower technologies.

The First novel technology is harvesting the leakage inductance energy, in a simple way without the use of an active clamp. The energy is extracted via a passive clamp in an ingenious way and the harvested energy is used to obtain zero voltage switching using a Second novel technology, by the use of a current injection circuit wherein a narrow quasi resonant pulse of current is induced in the primary of the transformer to discharge the parasitic capacitance reflected across the primary switch ensuring ZVS in any operating condition. This method extracts the energy from the parasitic capacitance reflected across the primary switch which is dissipated in hard switching mode of operation and sends said energy to the input voltage source, creating the most efficient method for producing ZVS. As a result of ZVS achieved in any operating conditions, including burst mode of operation, there is no voltage spike across the synchronized rectifier, which does not require any snubber.

The combination of these two novel technologies creates the “Ideal Flyback” topology which enjoys outstanding performances in a simple, low components count and low cost. Rompower 65W High Efficiency Adapter leads the world in respect of efficiency and other key characteristics due to technological advantages.

Rompower Technology Advantage in Reaching the Highest Power Density 65W Adapter

In Figure 2 the picture is depicting Rompower  65W Ultra High Density AC/DC adapter, with a volume of 31.6cm3, the highest power density adapter.

To reduce the size of the AC/DC adapter to 31.6cm3 the most important element is the reduction of the heat dissipation which requires a  very high efficiency. The very high efficiency is obtained by combining First novel technology together with the Second novel technology. Further, the size reduction requires innovative solutions for the magnetics as presented in the Rompower’ High Density Magnetic Structure, US Patent 11,842,835  One of the challenges in increasing the power density in AC/DC adapters is the EMI compliance due to the proximity between the input AC and sections of the circuit with very high dV/dt and dI/dt. Rompower has developed technologies for the Common Mode suppression in the transformer and as a result reducing the size of the EMI filter and increasing the power density. Rompower’ s novel technology presented in the US Patent , US Patent 12,132,397 increases also the efficiency of the transformer by reducing the dissipation in the EMI filter.

Rompower 100W AC/DC Adapter

In Figure 3 the efficiency of the Rompower 100W AC/DC adapter is presented versus the best competitors on the market. The efficiency gain of Rompower’ s adapter averages is due to Rompower technologies.

Rompower Technology Advantage in Reaching the Best World Performances for 100W AC/DC adapters as depicted in Figure 3.

The significant gain in efficiency over the competition is due to seral key Rompower technologies.

The First novel technology is harvesting the leakage inductance energy, in a simple way without the use of an active clamp. The energy is extracted via a passive clamp in an ingenious way and the harvested energy is used to obtain zero voltage switching using a Second novel technology, by the use of a current injection circuit wherein a narrow quasi resonant pulse of current is induced in the primary of the transformer to discharge the parasitic capacitance reflected across the primary switch ensuring ZVS in any operating condition. This method extracts the energy from the parasitic capacitance reflected across the primary switch which is dissipated in hard switching mode of operation and sends said energy to the input voltage source, creating the most efficient method for producing ZVS. As a result of ZVS achieved in any operating conditions, including burst mode of operation, there is no voltage spike across the synchronized rectifier, which does not require any snubber.

The combination of these two novel technologies creates the “Ideal Flyback” topology which enjoys outstanding performances in a simple, low components count and low cost. Rompower 100W High Efficiency Adapter leads the world in respect of efficiency and other key characteristics due to technological advantages.

In Figure 4 the picture is depicting Rompower 100W High Density AC/DC adapter, with a volume of 78cm3.

To reduce the size of the 100W AC/DC adapter to 78cc the most important element is the reduction of the heat dissipation which requires a very high efficiency. The very high efficiency is obtained by combining First novel technology together with the Second novel technology. Further, the size reduction requires innovative solutions for the magnetics as presented in the Rompower in US Patent 12,132,397 which addresses one of the challenges in increasing the power density in AC/DC adapters which is the EMI compliance due to the proximity between the input AC and sections of the circuit with very high dV/dt and dI/dt. In the US Patent 12,132,397 the Common Mode is suppressed in the transformer and as a result the size of the EMI filter is decreased increasing the power density and also the efficiency