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Unformatted text preview: lecture, but are also in the notes and in the book, so you can read ahead. Beware of thermal runaway: the thermal stability factor, K, given below, must be less than 1 or the push pull circuit can spontaneously destroy itselt. Vcc is the supply voltage. Re the emitter degeneration, and the theta terms are thermal resistances. e e case junction cc R r V C mV k + + + = ) ( ) / 2 . 2 ( ambient heatsink heatsink case case junction is given on the transistor datasheet, heatsink case should be less than 2 C/W if you firmly attach the transistor to the heatsink with minimal air gaps, thermal conductive compound, and a thin mica insulator. ambient heatsink is discussed on the web ( http://web.telia.com/~u85920178/begin/heat-0.htm ) , who give ) / ( / 50 2 cm W C A ambient heatsink , where A is the surface area of the heat sink. Heat sink surfaces should be vertical for best thermal convection....
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This note was uploaded on 08/06/2008 for the course ECE 137AB taught by Professor Rodwell during the Winter '08 term at UCSB.
- Winter '08