USB Power Delivery (PD) 3.1 is an updated specification that increases the power delivery capabilities of USB-C connections, allowing for up to 240W (48V, 5A) compared to the previous 100W limit of USB PD 3.0. This enhanced power delivery, known as Extended Power Range (EPR), enables charging of more powerful devices like high-performance laptops, monitors, E bikes and even some small household appliances via USB-C.
Rompower’ Technology Advantage in Reaching the Best World Performances for AC/DC adapters as depicted in Figure 1.
The 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 condition, including burst mode of operation, there is no voltage spike across the synchronized rectifier, which does not require any snubber.
To reduce the size of the 140W AC/DC adapter to 78cc the most important element is the reduction of the heat dissipation which requires a very high efficiency obtained by employing said First and 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 the EMI compliance, one of the challenges in increasing the power density in AC/DC adapters. That is due to the proximity between the input AC connection to the 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, reducing the size of the EMI filter, leading to an increase of power density and efficiency.
Rompower 140W AC/DC Adapter
Figure 1 presents the efficiency of the Rompower’ 140W AC/DC adapter versus the best competitors on the market. The efficiency gain of Rompower’ s adapter is due to Rompower technologies. For example, competitor 1 is using a complex and expensive solution sacrificing in process the power density. Rompower solution is using a simple “Ideal Flyback” topology which employs First and Second Novel Technology previously presented.
Figure 2
In Figure 2 is depicting Rompower 140W High Density AC/DC adapter, with a volume of 78cm3 and a power density of 29.5W/inc3.
Rompower Solutions for 180W, 240W and 330W
Rompower Technology Advantage in Reaching the Best Efficiency for 240W Adapter
The conventional Flyback topology has some limitations when used for offline applications and high voltage output like PD 3.1 EPR like 48V. The main problem faced in this topology is high voltage stress on the main primary switch due to a high voltage reflected from the secondary which is added to the input voltage.
Rompower has developed a Third novel technology, ZVS Two Transistor Flyback topology which eliminates all the drawbacks of the conventional hard switching two transistor flyback topology. The new Rompower technology also named “ideal two transistor flyback topology” transfers most of the leakage inductance into the secondary and a small portion of that energy is used to obtain zero voltage switching in the primary. There are no parasitic oscillations during the dead time and there are no spikes or glitches across switching elements in any mode of operation, eliminating the need for snubbers and allows operation at constant frequency which is a very desirable feature for system level EMI.
Based on the Third novel technology, Rompower developed a 240W AC-DC adapter with an efficiency of (94.2% @ 90Vac) and a power density (37.9W/inc3) uncased.
Rompower 240W AC/DC Adapter
Figure 3
Rompower Technology Advantage in Reaching High Power Density 240W Adapter of (37.9W/inc3) uncased.
Figure 4
The Third novel technology is a very good solution for power exceeding 180W. The simplicity of the flyback topology combined with the ability to optimize the utilization of the leakage inductance energy and guaranteed ZVS in any mode of operation makes this technology the most suitable for these types of applications. Competing technologies such as hybrid flyback do have boundaries of operation and require very complex control methodologies in order to maintain ZVS. Another key advantage of this technology over the competing technologies is the elimination of parasitic oscillations at lighter loads improving the EMI behavior. The Third novel technology allows the operation at constant frequency which is a major advantage for the EMI suppression at the system level
In Figure 5 is presented the efficiency of a 330W AC/DC Adapter using the Third novel technology.
Rompower 330W AC/DC Adapter
Figure 5
