T09.6 - Novel Magnetic Topology for ULTRA-Low Profile ZB-TLVR Voltage Regulator Modules

The growing electricity demand of data centers, driven by cloud computing, requires low-profile, high-density server boards to efficiently step down the distribution bus to digital rails. The prevalent two-stage approach relies on classic VRMs, which, while ensuring digital load regulation, constitute the least efficient link in the power distribution chain. High transient performance demands high switching frequencies, reducing VRM efficiency. State-of-the-art solutions, such as Zero-Bias TLVR (ZB-TLVR), improve transient response but suffer from increasing DCR losses with higher phase counts. This paper presents a novel magnetic topology for multiphase buck converters that overcomes these limitations, enabling low thickness, low DCR, high transient performance, and modularity. The proposed design achieves high efficiency even at low switching frequencies (e.g., 400 kHz), while maintaining a <3 mm profile and extremely low equivalent transient inductance, meeting modern data center requirements. A 12-phase prototype demonstrates 2.8 mm thickness, 1.2 A/mm² EDC current density, and a 1000 A transient with 5 A/ns slew rate.