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Final Control

Final Control. Introduction Thermal Circuits Thermal resistance Heat Sinks 2N3904 example OPA512 example JFET/MOSFET Review Summary. Types of Heat Sinks. For: Intel AMD PowerPC. Ball Grid Array. Surface Mount, Wave Solderable, Snap-down. http://www.wakefield.com/.

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Final Control

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  1. Final Control Introduction Thermal Circuits Thermal resistance Heat Sinks 2N3904 example OPA512 example JFET/MOSFET Review Summary

  2. Types of Heat Sinks For: Intel AMD PowerPC Ball Grid Array Surface Mount, Wave Solderable, Snap-down http://www.wakefield.com/

  3. System Parameters

  4. Defining Resistance

  5. J = junction C=case A=ambient PD Thermal Definitions TJ RθJC T= TJ -TA TC RθCA TA PD = power dissipated Rθ

  6. A simple thermal circuit PD = 120 mW =.12 W TJ RθJA = 2000C/W TA T = 240 C = TJ – TA = PD*RθJA TJ(max) = 1500C Max power: BJT ~ PCE FET ~ PDS SCR ~ PAK

  7. RθJC = Thermal Resistance from Junction to Case A complete thermal circuit with heat sink RθCS = Thermal Resistance from Case to sink RθSA = Thermal Resistance from Case to ambient PD TJ RθJC TC T RθCS T TS RθSA TA http://www.electronics-cooling.com/Resources/EC_Articles/JUN95/jun95_01.htm

  8. Common Cases http://sound.westhost.com/heatsinks.htm#introduction

  9. Mounting a heat sink http://www.gensemi.com/launch/ITO-220Rectifiers-external.ppt

  10. Mounting a TO-3 Heat Sink

  11. http://www.onsemi.com/pub/Collateral/2N3903-D.PDF 2N3904 BJT Specs

  12. BJT Amplifier Circuit: Spec says max. ambient temperature will be 1200C VC = 10 volts Example 1: RθJA for the 2N3904 is 200 0C/W, VCE = 9 volts VE = 1.05 volts PD = 9*20 = 180 mW PD = 180 mW =.18 W TJ TO-92 Style Case RθJA TA T = 360C = TJ – TA = PD*RθJA TJ(max) = 1500C

  13. PD = 180 mW =.18 W PD Adding a heat sink From Digikey: RθSA= 640C per Watt TJ RθJC TC T RθCS TS RθSA TO-92 Heat Sink TA RθTotal = 148.30C/Watt T = TJ-TA = 26.70C From 2N3904 spec: RθJC= 83.30C per Watt TJ(max) = 1500C From general: RθCS= 50C per Watt

  14. OPA 512 http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=OPA512 Absolute Max Internal power Dissipation = 125 Watts

  15. http://www-s.ti.com/sc/ds/opa512.pdf OPA512 Problem Need 30 watt AC amplifier for an audio application. The max temp will be 1040F First look at no heat sink: • OPA512, 125W, 15A • RθJA = 30 0C/ Watt • RθJC = .9 0C/ Watt TJ(max) = 1500C TA= 400C TJ TJ PD = 9*20 = 180 mW RθJC=.9 RθJA TC T TA RθCS PD = (TJ – TA)/RθJA= 110/30 = 3.67Watts TS RθSA TA 30 = (TJ – TA)/RT=110/RT RT = 3.67 0C/Watt total So RθCS+RθSA=3.67-.9=2.77

  16. TO3 Mounting Kit Mounting a TO-3 Heat Sink

  17. Pentium 4 Heat Sink http://www.aavidthermalloy.com/products/microp/desktop.shtml#Pentium%20IV

  18. Athlon Heat Sink http://www.aavidthermalloy.com/products/microp/desktop.shtml#AMD%20Processors http://www.aavidthermalloy.com/technical/index.shtml http://www.electronics-cooling.com/Resources/EC_Articles/JUN95/jun95_01.htm

  19. 125 Power Derating Curve RθJC= = 25 0C/Watt 5W 5 W 25 0C 150 0C

  20. JFET & MOSFET Review http://www.nzart.org.nz/nzart/exam/

  21. IRL630 HEXFET Switching Power MOSFET RθJC= 1.7 0C/Watt (max) RθCS= .50C/Watt (flat, greased surface) RθJA= 62 0C/Watt (max) http://www.irf.com/product-info/datasheets/data/irl640s.pdf

  22. RθJC= 1.7 0C/Watt (max) Max continuous drain current = 9 amps Rds = .4Ω Max power dissipated = 74 W @ 250C Linear derating factor = .59 W/0C Another Heat Sink Problem RθCS= .50C/Watt (flat, greased surface) RθJA= 62 0C/Watt (max) 125 TJ PD= = 2.02 W T 62 150 0C RθJC=1.7 PD TC T RθCS=.5 25 0C TS RθSA Best TO-220 at Digikey is: RθSA=4 0C/W TA So the max power that can be dissipated is: RθJC+RθCS+RθSA=1.7+.5+4=6.20C/W and PD=125/6.2=20.2W

  23. CMOS: Complementary Metal-Oxide Semiconductor http://www.webopedia.com/TERM/C/CMOS.html CMOS is a widely used type of semiconductor. CMOS semiconductors use both NMOS (negative polarity) and PMOS (positive polarity) circuits. Since only one of the circuit types is on at any given time, CMOS chips require less power than chips using just one type of transistor. http://tech-www.informatik.uni-hamburg.de/applets/cmos/cmosdemo.html

  24. Summary • Thermal Circuits • Thermal resistance • Heat Sinks • 2N3904 example • OPA512 example • JFET/MOSFET Review • IRL630 Heat Sink example • Next • Industrial Electronics • SCR • TRIAC • DIAC • Stepping Motors

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