Let’s peel back the curtain on how Analog Devices (ADI) is leading the charge, crafting power solutions that not only keep up with AI’s appetite but redefine what’s possible in efficiency, density, and reliability.
The Multiphase Revolution: Turning Chaos into Control
When faced with sky-high current surges, plummeting voltages, and spiking temperatures, the old approach, one big voltage regulator, simply can’t keep up. Enter the multiphase architecture: a tightly orchestrated dance of parallel power stages working in lockstep to both share the load and react to fast changes.
Key advantages?
- Lightning-Fast Transient Response: Multiphase designs react in microseconds, absorbing sudden current demands and smoothing out potentially disastrous dips or spikes.
- Sharper Efficiency: By spreading the load between phases, total losses are reduced, enabling higher current delivery without ballooning heat.
- Scalability: Want to power the next generation of AI ASICs? Simply scale up as the current rises, without redesigning your whole power system.
The ADI solution takes this even further by combining high-integration ICs, advanced control algorithms, and their game-changing coupled inductor technology.
Meet the Heroes
Two key components are at the heart of the ADI multiphase marvel. The MAX16602 multiphase controller is a flexible powerhouse that controls up to 16 phases in parallel, with an advanced modulation scheme that brings phased power ramp-up and ramp-down to near-instant speeds. Each phase’s activity is perfectly synchronized, responding dynamically to AI’s ever-changing draw. The MAX20790 monolithic smart power stage combines FETs, drivers, and high-precision current sensing into a single, ultra-compact package, unlike discrete designs full of parasitic delays and wasted heat. With built-in fault protection and direct communication with the controller, it’s both smarter and safer.
Figure 1: An 8-Phase VR Design with High Integration Power Chipsets Facilitates a High Density Design with Less External Connections
Dynamic Load Line Control: The Secret Weapon Against Voltage Fluctuations
Handling huge swings in current without massive, expensive banks of output capacitance is the holy grail of AI PoL design. The secret? Dynamic load line control.
With the ADI controller, the output voltage is automatically adjusted based on load, keeping the xPU well within its safe window: higher when the load is light and dipping only as much as needed when current surges. This means:
- Minimal Voltage Deviation: Step changes from 40 A to 360 A are met with barely a ripple.
- Crash-Proof Operation: With perfect positioning, xPU rails never wander outside their min and max—no over- or undervoltage risk.
- Compact Designs: Less need for bulk capacitance translates into smaller, denser, cooler boards.
Figure 2: Transient Plot of a 16-Phase VR for 40 A to 360 A Step Load at 800 A/µs Slew Rate
A Decade of Innovation: Coupled Inductor Technology
The ADI coupled inductor (CL) isn’t just a performance tweak. It’s a revolution in managing both steady-state and transient loads. CLs act as a big inductance in a steady state with efficient energy transfer when things are calm. They also offer low inductance during transients, reacting faster than traditional inductors when a power surge occurs. This results in 50% higher efficiency and almost half the physical size compared to discrete magnetics. And it offers better current ripple cancellation, enabling tighter, more reliable AI designs.
Figure 3: A Series of Coupled Inductors Commonly Used with ADI Multiphase VR Designs
The Heat is Off: Top-Side Cooled Packaging
With all this current in dense packages, thermal control becomes mission-critical. Both the MAX16602 and MAX20790 feature exposed top-side thermal pads and advanced packaging, allowing heat to move directly from the chip to air. The outcome? Lower operating temps, tighter designs, and extended hardware life.
Proof in the Performance
Don’t just take our word for it. The 16-phase evaluation board easily delivers up to 350 A with best-in-class efficiency at 400 kHz switching frequency.
Figure 4: Efficiency Plot of a 16-Phase AI VR Evaluation Board Design
Conclusion: Your Power Delivery “Easy Button” for AI
The ADI multiphase controller, monolithic smart power stages, and innovative coupled inductors aren’t just a response to AI; they’re the power delivery partner you need to innovate confidently. And the platform takes the guesswork out of managing voltage transients, maximizing density, and protecting xPUs from the wildest AI workloads.
Up next, we’ll look at what’s waiting on the horizon, including the radical new era of vertical power solutions that could reshape the entire PCB.
Read all the blogs in the Powering AI Accelerators series.