In response to the ever-increasing demands of high-performance applications such as artificial intelligence, machine learning, and big data mining, XPU operating currents have risen to hundreds of amperes. Point-of-charge power architectures, where high-current power supplies are placed close to the XPU, mitigate power distribution losses on the motherboard, but do nothing to reduce interconnection problems between the XPU and the motherboard. With the increase in XPU currents, the short remaining distance to the XPU ("last inch") consisting of motherboard conductors and interconnects within the XPU socket has become a limiting factor in XPU performance and overall system efficiency.
Vicor's new Power-on-Package Modular Current Multipliers (MCMs) fit inside the XPU package to extend the efficiency, density, and bandwidth advantages of Vicor's Power Factor Architecture, already established in 48V Direct-to-XPU motherboard applications. As current multipliers, the MCMs, mounted on the XPU substrate under or outside the XPU package lid, are driven at a fraction (e.g., 1/64) of the XPU current by an external Modular Current Controller (MCD). The MCD, located on the motherboard, controls the MCMs and precisely regulates the XPU voltage with high bandwidth and low noise. The solution, consisting of two MCMs and one MCD, enables the delivery of up to 320A of continuous current to the XPU, with a peak current capacity of 640A.
With the MCMs mounted directly on the XPU substrate, the XPU current supplied by the MCMs does not flow through the XPU contact. And, because the MCD controls the MCMs at a low current, the MCD's power can be efficiently directed to the MCMs, reducing interconnect losses by a factor of 10, even though 90% of the XPU pins typically required for power delivery are reclaimed for I/O functionality. Additional benefits include a simplified motherboard design and a substantial reduction in the minimum bypass capacity required to keep the XPU within its voltage limits.
Two Power-on-Package devices have been initially introduced: the MCM3208S59Z01A6C00 Modular Current Multiplier (MCM) and the MCD3509S60E59D0C01 Modular Current Multiplier (MCD) Controller. Multiple MCMs can be operated in parallel to increase current capacity. The MCM's small package size (32 mm x 8 mm x 2.75 mm) and low-noise characteristics make it compatible with co-packaging high-performance, noise-sensitive ASICs, GPUs, and CPUs. The operating temperature range is from -40°C to +125°C. These devices are the first in a portfolio of Power-on-Package solutions scalable to various XPU needs.
