Product review: Helix’s MuxCapacitor voltage conversion IP

By Maurizio Di Paolo Emilio, contributing writer

MuxCapacitor  is a proprietary voltage-conversion technology developed by Helix Semiconductors. Thanks to its high efficiency, the MuxCapacitor conversion IP allows Helix to build highly integrated power ICs, usable in a variety of applications that require AC/DC or DC/DC power conversion. By implementing this technology through a high-voltage SOI CMOS process, these devices can support input voltages up to 400 VDC, suitable for use in most applications in which conversion from alternating current to direct current is necessary. The AC/DC converters are suitable for developing power supply solutions both with and without transformers, ensuring an average end-to-end efficiency of over 95% in both cases.

MuxCapacitor technology also proves to be particularly useful in managing power dissipation under load-free conditions. When the load absorption is zero, the proprietary IP has an absorption of less than 5 mW without producing any effect on the value of the output voltage, which remains at the required value.

Another important family of devices developed by Helix Semiconductors concerns the DC/DC converters, mainly aimed at intermediate voltage-conversion applications. These converters have input voltages between 24 VDC and 60 VDC, with an average efficiency of over 94% and absorption in the absence of a load of less than 5 mW.

The typical applications of the Helix AC/DC voltage converters are as follows: USB-C−compatible output voltages, smart outlets, IoT and IIoT gateways, remote sensors, and smoke and carbon monoxide (CO) detectors. DC/DC converter applications include telecom blades, data centers, cloud servers and racks, PoE devices, wireless access points, security cameras, VoIP phones, industrial controllers, HVAC, and IoT and IIoT gateways.

An overview of MuxCapacitor technology
In the last few years, there has been a proliferation of electronic devices and applications, which has resulted in a growing demand for power management solutions, both in direct and alternating current.

To continuously reduce power absorption, required by both industrial and consumer applications, it is necessary to design solutions and devices that offer very high efficiency, minimizing losses and power dissipation. Additionally, aspects related to current regulations, such as those that are purely ecological, should not be overlooked in contributing to environmental protection.

In this context, the MuxCapacitor technology represents a break with traditional solutions. It achieves a very high level of efficiency in all load conditions, combined with minimum energy waste. The high efficiency obtainable through the MuxCap capacitive conversion technique can also be combined with another proprietary Helix technology: CapIso. CapIso offers a solid-state capacitive isolation, eliminating the need for bulky and expensive transformers in the design of AC/DC converters and isolated DC/DC converters. The use of MuxCap and CapIso technologies, therefore, makes it possible to obtain straightforward, compact, and highly efficient solutions for power conversion.

The power efficiency, expressed as a percentage, is obtainable with a solution based on the MuxCapacitor technology, as shown in Fig. 1 . As can be seen, the blue curve corresponds to a very high-efficiency value and remains almost constant as the load varies (also, the load is expressed as a percentage). The red curve refers, instead, to a common type of solution based on a traditional magnetic-based technology. It should be noted that the second solution achieves efficiency values comparable to those of the MuxCapacitor solution only for a load usage of over 50%, while for lower load values, the efficiency is much lower.

Fig. 1: Efficiency comparison between a MuxCapacitor solution and a traditional one. (Image: Helix Semiconductors)

The efficiency curve highlights the advantage of the MuxCapacitor power delivery. Not only is the efficiency extremely high, but there is no efficiency penalty at low operational loads. Helix MuxCapacitor chipsets include up to three stages, wherein each stage consumes less than 1-μA quiescent operating current. MuxCapacitor, based on a switched-capacitor charge pump technology, achieves greater than 98% efficiency and is suitable for both isolated and non-isolated, AC/DC and DC/DC, buck, or boost power-conversion solutions.

The upper side of Fig. 2 shows an application diagram relating to a generic buck or boost voltage converter based on the MuxCapacitor technology. As can be seen, only a few external flying capacitors and a capacitor connected between the output voltage V_OUT and ground are needed to obtain a compact and integrated single-stage voltage converter. As an example, the lower side of Fig. 2 shows two configurations (or networks) of external capacitors, through which it is possible to achieve, respectively, a voltage gain of 1.5 or 0.66.

Fig. 2: Application diagrams related to the MuxCapacitor converter in boost and buck configurations. (Image: Helix Semiconductors)

On the other hand, Fig. 3 shows a typical scheme related to the combined use of the MuxCapacitor and CapIso technologies. The IP built with MuxCap technology is implemented both on the primary and the secondary side of the chipset, while the inner circuit made with CapIso technology provides a capacitive type of barrier. A solution of this type, which has obtained the approval of the Underwriters Laboratories (UL) with regards to safety aspects, offers the critical benefit of eliminating the need for an isolation transformer.

Fig. 3: Scheme of combined use of MuxCap and CapIso technologies. (Image: Helix Semiconductors)

For the complete article with more detailed information on the Helix MxC 200 and MxC 300 product families, please visit EDN Asia .