Renesas PMIC Reference Designs Streamline Power Management for Xilinx FPGAs

Power management is a cornerstone of modern FPGA-based systems. A well‑designed supply network not only improves efficiency but also extends device life, which is why the demand for sophisticated Power Management ICs (PMICs) continues to surge.

Why FPGA Power Management Demands Expertise

FPGAs draw highly dynamic currents with steep slew rates, requiring a controller that can deliver precise current steps while keeping output voltage fluctuations to a minimum. Engineers often spend most of their time coding logic, not designing power rails, so a proven, scalable solution is essential.

Renesas’s Xilinx‑Focused Reference Designs

Renesas Electronics has released three turnkey PMIC reference designs tailored to Xilinx’s flagship families: Artix‑7, Spartan‑7, and Zynq‑7000 SoC. Each board is based on Renesas’s ISL91211AIK or ISL91211BIK multi‑phase PMICs in compact 4.7 × 6.3 mm, 35‑ball BGA packages with a 0.8 mm pitch.

• ISL91211A‑BIK‑REFZ (Artix‑7) – Combines the ISL91211AIK/BIK PMICs, an ISL80030 3‑A synchronous buck, and an ISL21010DFH312 micropower reference. It achieves up to 95 % efficiency across multiple rails and accepts a 5‑V input from an AC/DC adapter or DC supply.
• ISL91211BIK‑REF2Z (Spartan‑7) – Utilizes the ISL91211BIK PMIC with an ISL80030 buck to supply VCCINT, VCCBRAM, VCC_DDR, VCCAUX, and VTT, also from a 5‑V source.
• ISL91211AIK‑REFZ (Zynq‑7000) – Employs the ISL91211AIK PMIC, an ISL9123 low‑Iq buck for VTT, and two ISL80030 buck converters to drive VCCINT, VCCBRAM, VCC_DDR, and VCCAUX.

Each board supports Xilinx’s DDR memory families—DDR3, DDR3L, DDR4, LPDDR2, and LPDDR3—and delivers a total output current of up to 20 A. The design’s 2‑MHz switching frequency, 22‑µF output capacitors, and small inductors keep the solution compact while providing fast load‑transient response.

R5 Modulation Technology: Next‑Generation Efficiency

All three PMICs feature Renesas’s proprietary R5 modulation. This current‑mode hysteretic controller offers ultra‑fast transient response, dynamic voltage scaling, and the ability to lower switching frequency under light loads, dramatically reducing losses.

The R5 algorithm operates with a synthetic current ramp (Vcr) that emulates the inductor waveform, eliminating the need for direct current sensing. In steady state, the hysteretic window maintains a constant duty cycle, enabling the loop to adapt quickly to load changes.

Figures 2 and 3 illustrate the R5 architecture and its efficiency gains across load conditions.

Figure 2: Simplified diagram of Renesas’s R5 technology (Image: Renesas)

Figure 3: Efficiency of R5 modulation technology (Image: Renesas)

Ready for Production

Each reference board comes with a comprehensive user’s guide, full schematic, bill of materials, and PCB layout files, available through Renesas’s global distribution network. The designs are ideal for industrial applications such as motor control, machine‑vision cameras, PLCs, home gateways, portable medical devices, and wireless equipment.

For more information or to download the design files, visit Renesas’s product page or contact a local distributor.