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27 Thermal modeling of the package and its dissipation performance at the power levels is critical. Vendors provide detailed thermal models, and the basic modeling is fairly straightforward. Vendors also provide application notes that walk designers through the basics with examples. The initial modeling usually only requires a spreadsheet, but a more advanced thermal- analysis applications program may be needed to investigate heat-sinking and related options. Both MOSFETs and IGBTs can be paralleled to carry higher current or physically spread the thermal sources—often a need in motor drive—but each needs a different conguration of additional passive components to balance and equalize current ow. There's more to modeling than the component's thermal situation. Even if you can get rid of enough of the heat from the MOSFET or IGBT to keep it below its SOA rating, that heat has to go somewhere. In some cases, there is an easy dissipation path to "outside," but in many cases, the heat the device gives off becomes a problem for the rest of the PC board or box. Therefore, the thermal analysis must look at system-wide impact of dissipation, especially as many motor applications are in enclosed or challenging environments where ambient temperatures are high and cooling airow is low. Making the choice There is no single "best" choice of individual model or even between a MOSFET or IGBT in most cases. The reality is that the decision is made on many performance parameters and their relative priority, as well as availability and cost. Fortunately, ST Microelectronics manufactures a variety of both MOSFETs and IGBTs, so they can provide a balanced assessment of the decision of which type of switch to use. In addition to in-depth data sheets, ST also offers solid application notes on general design issue, supplemented with detailed designs (and their analysis) for specic applications plus a library of proven reference designs (layout, BOM) that you can use as a starting point. Video STMicroelectronics Low-Voltage STSPIN Motor Drivers STMicroelectronics' STSPIN32F0 is a system-in-package that reduces the number of components and design complexity for driving three-phase BLDC motors. It includes an advanced BLDC controller that integrates 3 half-bridge gate drivers for power MOSFETs or IGBTs, with bootstrap diodes and an interlock that prevents cross-conduction. It also includes a fully featured STM32 MCU with an ARM ® Cortex ® -M0 core to perform FOC, 6-step sensorless, speed control loops, and other advanced driving algorithms. The STSPIN32F0 can operate from an 8 to 45 V supply and includes a 12 V linear regulator for the gate drivers and a 3.3 V switching regulator to supply the MCU and external components if needed. It's versatility makes it ideal for consumer and industrial motor drive applications. ^ For motor-drive applications, starting guidelines are that MOSFETs are a better choice at lower voltages and currents, and at higher switching frequencies; IGBTs are a better choice at higher voltage/current and lower frequencies.

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