50W DC/DC converter targets Power-over-Ethernet applications

11th April 2014
Nat Bowers

Suitable for Power-over-Ethernet (PoE), as well as 24 or 48V telecomms systems applications, Ericsson has introduced a 50W DC/DC converter module. The PKU5510E features an ultra-wide input range of 18-75V, an output current of 15A at 3.3V output and a built-in functional isolation of 2250V DC that meets the requirements specified by the IEEE802.3 Ethernet networking standard.

The latest evolution of Ericsson’s PKU family, this module combines the thermal enhancements integrated in the recently announced PKU4116C  with an optimised fly-forward topology. It also meets Basic Insulation requirements according to IEC/EN/UL60950. The PKU5510E has been designed for applications that have to accommodate both telecomms system bus voltages of 24 and 48V, while also being a best-in-class product to supply voltages to Power-over-Ethernet based applications such as remote antennas, WIFI repeaters, basestation microcells, CCTV/camera monitoring systems and a variety of different sensors.

With its ultra-wide input and high efficiency, the PKU5510E is also a suitable solution to power industrial applications and many others that use remote power feeds, where a module is required to operate irrespective where it is connected or indeed of the length of the line cable. The wide input range offers another benefit for applications that require a hold-up capacitor to prevent the loss of vital data in the case of line disruption. As the module can operate at 18V, a hold-up capacitor can maintain voltage for a longer period of time when compared to a competitive power module with a narrower input range. And because of the module’s wide range of operation, this can even reduce the amount of capacitors required and therefore reduce cost.

Designed for applications that are subject to peak currents and environment with very low natural convection or airflow, the PKU5510E embeds a unique overload protection system. In these types of applications, the overload protection must prevent false triggering while simultaneously guaranteeing reliable protection from overloading. A solution for this complex situation has been achieved by combining two Over-Current Protection (OCP) methods. In the case of a short-duration overload, the hiccup-mode OCP uses a tightly controlled cycle-by-cycle current limitation; and in the case of longer overload, the hiccup-mode OCP will trigger for conventional hiccup protection.

However, protection is not just limited to two hiccup modes, as the hiccup activation time is proportional to temperature and becomes shorter with an increase in temperature, thereby limiting the energy dissipated during this period. Following activation of the Over-Temperature Protection (OTP), the module thoroughly checks the OTP threshold to prevent any restart that could damage the module.

Available in an industry-standard sixteenth-brick footprint with dimensions of 33x22.9x9.4mm, the device delivers up to 50W, and provides up to 92% efficiency at 50% load and 27V input, guaranteeing low power dissipation and reduced energy consumption.

Built upon an enhanced thermal layout, the PKU5510E delivers outstanding performance for applications that have limited airflow, which is usually the case in low-power PoE systems. In the case of natural convection, the module delivers full performance up to 80°C; and when the system experiences 3.0m/s convection cooling, full power can be delivered up to 96°C. Offering an MTBF of 4.9m hours, the PKU5510E meets safety requirements according to IEC/EN/UL 60950-1 and offers input/output isolation of 2250V DC. It also includes various protection features, including output-over-voltage protection, input-under-voltage shutdown, over-temperature protection, output short-circuit protection and pre-biased output.

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