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讨论了用于功率晶体管的热阻的理想概念。因为将热阻概念应用到器件上去时所作的两个基本的假设是无效的,所以使用热阻概念时要很小心。与此相反的两个假设是:1)功率晶体管的结温不是空间均匀的;2)对于所有的工作点没有一个唯一的热阻值。也讨论了测量功率晶体管结温(热阻)的各种电学方法,而重点放在只在发射极加开关的测量方法,这个方法是常用的标准的测量方法。还讨论了正向偏置安全工作区(SOA)极限的发生和测量,同时指出因为电流拥集的出现及由此引起的热点,给定的 SOA 极限经常允许器件在很危险的高的结温下工作。讨论了能测定峰值结温和电流拥集开始发生的电学测量方法,同时指出这些方法怎样用来改进 SOA 极限的发生。
The ideal concept for the thermal resistance of power transistors is discussed. Because the two basic assumptions made when applying the thermal resistance concept to the device are not valid, be very careful when using the thermal resistance concept. Two hypotheses, on the other hand, are: 1) the junction temperature of the power transistor is not spatially uniform; 2) there is not a single thermal resistance for all operating points. Various electrical methods for measuring the junction temperature (thermal resistance) of power transistors are also discussed, with the emphasis being placed on the measurement method of switching ON ONLY at the emitter. This method is commonly used as a standard measurement method. Also discussed is the occurrence and measurement of forward-biased safe operating area (SOA) limits, while noting that due to the advent of current crowding and the resulting hot spots, given SOA limits often allow the device to operate at very dangerous high junction temperatures Work Discusses the electrical measurement methods that can be used to determine peak junction temperature and current crowding, and how these approaches can be used to improve the SOA limit.