ROHM, together with Avnet, a leading supplier of electronic products and embedded solutions, developed a reference power supply optimized for Xilinx’s FPGA Spartan-7.
In recent years, FPGA power supplies are increasingly demanding high accuracy low voltage, complicated startup sequences. At the same time, designers are constantly faced with the need to upgrade their designs to feature smaller form factors, greater energy savings, and lower costs, which are difficult to achieve within a short period. In response, ROHM offers an optimized power supply reference design for FPGA power supplies that allows designers to reduce development load while meeting market demands.
The Spartan-7 (which this reference design was developed for) is ideal for industrial and consumer applications that leverage connectivity with sensor fusion and embedded vision.
ROHM’s reference power supply design consists of a verified power supply that safely starts and operates Xilinx’s Spartan-7. This reference power supply includes the BD95602MUV power supply IC that delivers superior response characteristics, along with the BD9B305QUZ, BD9F500QUZ, and BD9F800MUZ designed to provide the current capability demanded for each power supply as well as the BD35395FJ-M DDR3L termination power supply, making it possible to generate supply voltages that meet FPGA voltage accuracy specifications from 12V input while also supporting the necessary startup sequence.
Reference design materials including circuit diagrams, BOMs, and board layouts are available for download.

The components of ROHM’s reference power supply design for Spartan-7 are shown below.
The FPGA featuring 12V input is the Spartan-7 XC7S50.
The following 5 different power supply ICs are used in the reference design.

• BD95602MUV-LB: External FET type 2ch synchronous rectification buck DC/DC controller featuring excellent transient characteristics. The operating frequency, overcurrent detection value, and operating mode can be set (via terminals).
• BD9F500QUZ: 1ch synchronous rectification DC/DC converter capable of up to 5A output. The operating frequency, overcurrent detection value, and operating mode can be set.
• BD9F800MUX: 1ch synchronous rectification DC/DC converter capable of up to 8A output. The operating frequency can be set from 300kHz/600kHz (via terminals).
• BD9B305QUZ: 1ch synchronous rectification DC/DC converter capable of up to 3A output.
• BD35395FJ-M: Termination regulator compatible with DDR1/2/3/3L. Designed to supply up to 1A sink/source output current.