Altera/Enpirion DC-DCs aim to solve FPGA-power-supply challenges

October 22, 2013 // By Graham Prophet
Power converter configurations specifically targeted at providing the correct power feeds to large Altera FPGAs will improve system power efficiency by up to 35% while reducing board area by up to 50%.

Altera's acquisition of Enpirion, designers of small-outline high-efficiency DC/DC converter modules, was one of the more unexpected corporate merger-and-acquisition deals – now, the company has announced the first results from the joint operation that are specifically aimed at Altera FPGAs. According to an Altera's Mark Davidson, marketing director, power business unit, the company's customers often face big challenges in providing correct power supplies to its FPGAs. There are multiple power rails, requiring precisely-controlled levels at low voltages and high currents: demanding transient response performance must be met; and in addition, correct sequencing at power-up and power-down is essential. Its customers, Davidson says, have had to apply, “engineering bandwidth to areas that are not key [to designing the actual functionalities of the FPGA]”

Accordingly, Altera has announced “Power-optimised FPGA reference designs” - both product and design process – to simplify the development of FPGA-based systems. Primarily for Cyclone V parts, there are four reference designs in this release. Davidson says its parts built in 14-nm silicon technology will require ±3% voltage rail stability and as with all complex FPGA designs, actual currents will be dependent on the configuration and operating parameters of the FPGA so point-of-load regulation will need to handle large current variations. Up to five power rails are needed for core, I/O, PLLs, peripherals and SERDES functions, with appropriate sequencing. Davidson emphasises the need for voltage stability, “[when] supplying a SERDES [function], noise on the rail appears as jitter on the data stream.” “All FPGAs need significant bulk capacitance,” he adds, before going on to detail how the solution reduces that need.

Enpirion brought expertise in three area, in its miniature-packaged-DC/DC designs; efficient high-frequency switching in CMOS; miniature magnetics; and the packaging itself. The four reference designs exploit those features, as “ turnkey” power solutions that increase power efficiency by up to 35% (that is, reduce the losses by that percentage), reduce board area (used by the regulation)