An Automotive-Grade Monolithic Masterless Fault-Tolerant Hybrid Dickson DC-DC Converter for 48-V Multi-Phase Applications

Abstract

Autonomous-driving features necessitate a fault-tolerant (FT) power-management unit in 48-V automotive applications. This article presents a monolithic single-phase closed-loop masterless FT four-to-one hybrid Dickson converter IC for high-conversion-ratio 48-V automotive multi-phase applications. The chip includes: 1) a mixed-signal droop-based valley-current ON-time quasi-fixed-frequency control, which enables masterless multi-phase operation capability; 2) single-point short-circuit fault and open-circuit fault detection and blocking of any power switches or flying capacitors; 3) an optimized high-voltage (HV) power stage with fully integrated flying-capacitor-sourced gate drivers without any external bootstrap capacitors; 4) a glitch-free cross-coupled bootstrapped HV level shifter; and 5) a dual-leg bidirectional closed-loop current-sensing circuit optimized for the hybrid Dickson topology. The design was fabricated in a 0.13-μ m 90-V automotive silicon-on-insulator (SOI) bipolar-CMOS-DMOS (BCD) process. The measured results confirm the operation over 20-60-V input, 3.3-V nominal output, 3-A maximum load, and 320-kHz effective switching frequency within the automotive-grade-40 °C-+125 °C ambient temperature. The design achieves above 90% measured efficiency at maximum conversion ratio and load at room temperature. A three-phase system is used to evaluate and confirm the fault-blocking capability and continuous power delivery upon detection of a fault.