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26 DESIGN007 MAGAZINE I JANUARY 2022 has a smooth, unblemished surface to prevent arcing. High-Voltage Design: Component Selection High-voltage relies on passive as well as active components. While design specifica- tions for high-voltage resistors may require low inductance and low temperature coefficients, ceramic capacitors must have high resistance, high temperature coatings and dielectrics that withstand high-voltages. Capacitors used in high-voltage circuits also should exhibit sta- ble electrical parameters with a wide range of applied dc voltages and under different envi- ronmental conditions. High-voltage semiconductor devices used for motor control circuits and power sup- plies include MOSFETs, insulated gate bipolar transistors, MOS-controlled thyristors, power FETs, and silicon-controlled rectifiers. PCB design rules must follow manufacturer guide- lines for not exceeding values that can destroy the devices. For example, high-voltage circuits may require components that have higher breakdown voltage ratings and the capability to handle higher currents. Circuit optimization can protect those devices from inductive loads or any large stray inductance that can cause reverse volt- ages that damage the components. Good cir- cuit design also routes cables and shielding to prevent any large voltage or current tran- sients that can induce instantaneous voltages on control lines. DESIGN007 Editor's note: This article originally appeared as a blog post on the Cadence Design Systems website. Celso Faia is a principal application engineer, and Davi Correia is a senior principal application engineer, both with Cadence Design Systems. by Terry Jernberg The drive for faster through- put, increased mobility, and maximum efficiency in mod- ern electronic devices has made power delivery a criti- cal piece of design success. However, meeting the power needs of modern designs is anything but simple. To achieve a robust design, each supply must be capable of deliver- ing sufficient current to every dependent device. In addition, those supplies must be both stable (able to maintain narrow voltage tolerances) and responsive (capable of adapting to transient current demands). Identifying and resolving power delivery problems late in the design process is incredibly difficult. If design power requirements aren't con- sidered upfront, it can lead to schedule delays and a significant amount of debugging time in the lab. Implementing a power-driven, PCB layout method- ology ensures the design process addresses critical power and signal integrity (SI) issues collectively at a time they can be easily solved. Power delivery network (PDN), power integrity (PI), return path analysis, and many new terms are evolving, but ultimately, it's the same plane layers, copper pours, and "heavy" etch that have been part of the layout process for decades. What's different now is that the tolerances we once could get away with can now ruin a product, potentially preventing its release and sales. The good thing is that best practices, combined with a solid understanding of your power system, can be incorporated into your PCB design efforts to achieve a successful PDN, and therefore a successful PCB. To read the full column, click here. Terry Jernberg is an applications engineer for EMA Design Automation, Inc. All Systems Go! Meet Power Delivery Requirements Upfront with Power-First PCB Implementation

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