New Infineon Flyback Converters Target Power Losses in USB Power Delivery

May 05, 2021 by Jake Hertz

This week, Infineon released a new USB-PD charger that leverages a flyback converter topology for maximal efficiency.

In most wall-powered electrical systems, one of the significant sources of power consumption is lost during the power conversion process. Between the wall power and the DC load, voltage generally needs to be rectified from AC to DC and converted from the rectified DC to a lower-level regulated DC. This whole process can result in large power losses. 


Inside a phone charger.

Inside a phone charger. Image used courtesy of Lady Ada


There are many takes on making converters that are aimed at maximizing efficiency. One example is the flyback converter, which has grown in popularity thanks to its simple output filter design and its ability to be used for multiple outputs. One example is using the flyback converter topology in cell phone chargers. 

As a testament to this, this week, Infineon released a new series of USB-PD-based chargers, which claim to leverage the flyback topology to achieve maximal efficiency. 


What is the Flyback Converter? 

A flyback converter is a switched-mode power supply (SMPS) DC/DC converter topology that operates on mutual induction.

In many ways, flyback converters are similar in operation to a buck converter. The main difference is that the flyback converter replaces the inductor with a transformer’s primary coil and utilizes the secondary coil for its output. 


Examples of a flyback converter and a buck-booster converter circuits.

Examples of a flyback converter and buck-booster converter circuits. Image used courtesy of Anurag Gupta


These circuits generally use a pulse width modulation (PWM) signal to control the base of a switching transistor, modulating the current flow through the primary winding of the transformer. When current flows through the primary winding, energy is stored as a magnetic field. When the current flow stops, the stored magnetic field collapses, and the release of energy appears at the secondary winding, where it is used as the output. In an actual circuit, feedback is utilized to monitor the output voltage and control the PWM signal as needed. 

The benefits of flyback transformers include isolation between the input and output, the high efficiency of SMPS, the ability to provide multiple output voltages, and, importantly, requiring very few components compared to other SMPS. 


Infineon’s XDPS2201

This week, Infineon made news by adding a new product to their lineup: a flyback converter aimed specifically at USB-PD applications.


Block diagram of the XDPS2201.

Block diagram of the XDPS2201. Image used courtesy of Infineon


According to the company, their new power supply, the XDPS2201, combines the benefits of both an asymmetric half-bridge flyback topology and a resonant converter to achieve natural soft switching. 

This soft-switching allows to greatly minimize switching losses and EMI, two of the most considerable pitfalls of SMPS. Along with this, the converter comes with a self-adaptive digital algorithm, which allows it to achieve the highest performance possible under different and varying input and output conditions. 

According to the datasheet, the converter can help achieve power densities higher than 20 W/inch^3 and efficiencies greater than 93%. 


Room for Growth 

As demand continues to grow for faster charging of mobile devices, more innovations need to occur in this space––and that’s seemingly exactly what Infineon is doing here. Increasing the efficiency of flyback converters while also helping minimize issues like EMI is a massive step in the right direction.



Interested in other phone charging news? Read more down below.

Xiaomi Says “Revolutionary” Long-Range Wireless Charging is Here—Critics Say Otherwise

A Breakthrough in Wireless Charging Enables Two Devices to Be Charged on the Road

Qualcomm’s Charging ICs Power Up Phones from 0–100% in 15 Minutes