Reverse power feed technology designed for next-gen xDSL

24th October 2014

Siobhan O'Gorman

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Critical for FTTdp and G.fast deployments, Reverse Power Feed (RPF) technology has been introduced by Microsemi. The PD81001 and PD70101 RPF chips are designed to be used with Broadcom's VDSL2 and G.fast chipsets. Integrated with low RDS(ON) FET, the PD81001 is an RPF Power Sourcing Equipment (PSE) chip. The chip, which has a built-in 3.3VDC output, features 10 external components.

10, 15, 21 and 30W RPF classes with single DC voltage input (32-57VDC) are supported by the RPF PSE chip. The chip provides powered device protection such as over load, under load, over voltage, over temperature and short circuiting. Phone off-hook protection and PSE line monitoring through SPI are also offered.

Integrated with a PWM controller, the PD70101 is an RPF Powered Device (PD) chip. The chip features a low RDS(ON) isolating FET switch which has an inrush current limit. Alongside over load and short circuit protection, the chip disconnects a signature resistor upon detection. For efficient synchronous rectification or active clamp, two out-of-phase driver stages are provided by the chip.

A maximum expected range of 250m is provided by G.fast, the new xDSL standard for 1Gb/s over copper. Shorter loop lengths are required to achieve the highest data rates with G.fast, which leads to the need for fibre to the distribution point. Due to their location, regulations of countries or economic reasons related to power grid hookup and monitoring the grid with a smart meter, these fibre-fed Distribution Point Units (DPUs) will require reverse power feed in some cases.

“We're excited to leverage our expertise in both DSL and remote powering applications to expand Microsemi’s portfolio in the broadband market in collaboration with Broadcom,” said Iris Shuker, Director of Product Line Management, Microsemi. "PD81001 RPF PSE used in the CPE paired with PD70101 RPF PD used in the DPU are based on mature technology which is being standardised in ETSI and BBF, and enables fast deployment of advanced DSL technologies with reverse power feed. Our solution is based on a metallic-signature handshake protocol and provides Broadcom’s DSL devices with inherent reliability and cost advantages over more complex communication based solutions."

"Broadcom is enabling advanced DSL broadband solutions with data rates that can reach 1Gb/s," said Jim McKeon, Senior Director of Product Marketing, Broadband Carrier Access, Broadcom. "Microsemi's RPF solutions simplify the deployment of FTTdp, allowing operators to reduce CAPEX and in turn foster the development of even more cost-effective DSL solutions."

The PD81001 is offered in a 4x5mm 24-pin QFN package, while the PD70101 is offered in a 5x5mm 32-pin QFN package.