Fault Detection in a Hybrid Dickson DC–DC Converter for 48-V Automotive Applications

Abstract

Autonomous driving features have introduced safety-critical processor modules. A 48-V network has been developed to enable efficient power distribution. A fault-tolerant high-voltage power management unit is required to ensure continuous power delivery to critical loads. This article compares the cost and efficiency penalty of accommodating the fault-tolerant capability in common dc-dc topologies. The comparison is verified using a 0.13-μm high-voltage automotive Bipolar-CMOS-DMOS SMARTMOS technology in a Cadence simulation environment. Besides, a quantitative reliability assessment of the single-phase and multiphase configurations is presented. This has led to the selection of the hybrid Dickson topology, which has the best electrical performance and comparable cost and reliability among all for high-conversion-ratio fault-tolerant 48-V automotive application. Moreover, this article presents a fast and robust short-circuit and open-circuit fault detection scheme for power switches and flying capacitors in a hybrid Dickson dc-dc converter. The detection method only observes the low-voltage switching node, which eliminates the challenges associated with high-voltage high-bandwidth sensing. The performance of the design has been verified using a multiphase 48-V-to-3.3-V 4-to-1 Dickson converter prototype. The measured results demonstrate that the short-circuit faults are detected within two switching cycles of 250 kHz, which is less than the 10-μs short-circuit immunity of commercial silicon devices.