Before we dive into specific application-based examples of noise and EMI mitigation, let's start with the basics. What is noise? What is EMI? What is ripple? How are they measured? What are some common approaches to limiting their effects? This section discusses these topics with a more conceptual approach to serve as a primer for the rest of the series.
Now that we understand the sources of EMI and noise in switching regulators, and some of the common approaches to mitigating each, let's take a closer look at real-world examples of reducing their effects. In this section we will examine the impacts of various mitigation techniques to help you decide which approach makes the most sense in your design. Techniques covered in this discussion include external component placement, filter options and design, frequency manipulation via spread spectrum or dithering, snubbers, boot resistors, and more.
Noise and EMI can be detrimental to sensitive analog signal chain circuitry. For this reason, many engineers automatically default to linear regulators. But, in doing so, they are essentially trading one problem (noise) for another (heat dissipation). In this section we will discuss what types of signal chain loads can be driven directly by a switching regulator to get low noise and EMI without sacrificing efficiency. We will also discuss when a linear regulator is absolutely needed to reach levels of noise not possible with a switcher.
Because of the potential havoc that interference can wreak in radio and safety critical systems, automotive electronics are subject to the most stringent EMI standards- the most common being CISPR25 Class-5. The materials below provide a discussion around the sources of EMI in an automotive environment and a comprehensive blueprint to understanding how to minimize it's effects.
The below introductory section features a video briefly discussing what exactly multi-phase buck regulators are, what applications they're suited for, and some of the challenges associated with implementing them. Additionally, the listed resources dive a little deeper into the topics covered in the video, providing further instruction in the beginning of your multiphase journey.
In designing with multiphase, Carmen works through a six-phase design for powering the core voltage of a networking ASIC, Marketing Manager George Lakkas explains why multiphase converters are ideal for high currents, and TI engineers blog about common concerns and use contexts.
In testing in the lab, Carmen takes a six phase buck regulator through basic validation testing in the lab with plenty of tips and waveforms shared. Let Carmen show you how to test transient response, input and output ripple, phase stability, and thermal performance. Additionally, TI engineers blog about various lab tricks related to multiphase devices.