Electromagnetic Interference (EMI) evaluation of a pseudo-constant frequency, hysteretic buck DC-DC converter for automotive applications

This paper presents an EMI evaluation of a hysteretic buck DC-DC converter designed for automotive applications. More specifically, the proposed converter’s performance with hysteretic control was analyzed in the context of conducted emissions and compared with same circuit but with fixed frequency PWM control. One particularity of the proposed convertor is that the operating frequency is fairly stable and the inherent frequency jitter of almost 1.5% at static loads, helps improving the EMI performance. Both convertors were analyzed in the same load and filtering conditions and the results show $\approx$ 20% reduction of the fundamental component’s magnitude at $1A$ and a 7.8 dB $\mu\mathrm{V}$ when the load is varied from 1A to 500mA.