Switch peak current mode control circuit for automobiles

How to increase the switching frequency beyond 1.7MHz to avoid AM band interference and how to provide fast load transient response is the ongoing pressure on automotive infotainment systems using switch mode power supplies. Today, multicore processors and system-on-a-chip (SoC) require a core voltage of less than 1V, which requires tight regulation from an intermediate voltage of 2.5V to 6V. At the same time, power supply designers need to meet multiple goals, such as providing high switching frequency, small and compact solutions, and fast transient response. This article will delve into the design optimization techniques for peak current mode control loops. This step-by-step design takes into account parametric variations, parasitic components and typical automotive requirements. The circuit is optimized using a series of asynchronous buck converter devices.

Introduction

Today's multi-core processors and system-on-a-chip (SoC) require core power supplies that are not only low voltage and tightly regulated, enabling ultra-fast transient response. In the test case we provided, the required core voltage was 1.2V, and the overall accuracy including transient response was +/–3%. Load transients are specified from 0.5A to 2A (within 400ns). In addition, the paper also describes the circuit behavior during load transients, as well as the related formula derivation and its application in this case.