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Experiment 5

-. +. Experiment 5. EE 312 Basic Electronics Instrumentation Laboratory Wednesday, September 27, 2000. Objectives:. Si Rectifier Forward I-V Characteristics Forward Conduction at Room Temp (T) at Elevated Temp (IVT Method) Characteristics of Zener Diodes

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Experiment 5

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  1. - + Experiment 5 EE 312 Basic Electronics Instrumentation Laboratory Wednesday, September 27, 2000

  2. Objectives: • Si Rectifier Forward I-V Characteristics • Forward Conduction • at Room Temp (T) • at Elevated Temp (IVT Method) • Characteristics of Zener Diodes • Forward Conduction at Room Temp • Reverse Conduction at Room Temp

  3. Semiconductor Diode Background: Two Types Vacuum Tube Diode

  4. + Anode I - Cathode One Way Semiconductor Diodes: Anode - Anode Cathode I + Cathode

  5. 670H16 Zener, Si metal case IN4742 Ge Glass case Anode + Cathode Types of diodes:

  6. ID ID VD ID VD R External Limit VD 1/RD Diode Piece-wise approximation VT

  7. Si Ge Tube Forward current (mA) Forward bias(V) Reverse bias (V) Reverse current (uA)

  8. Parameters: • Maximum average forward current (IF,Max) • Full-cycle average current IF that the diode can safely conduct without becoming overheated • PRV, PIV,or VRM • peak reverse voltage • peak inverse voltage • voltage reverse, maximum (Maximum allowable reverse-bias voltage for the diode) PRV rating of 200 V means that the diode may breakdown & conduct & may even be destroyed, if the peak reverse voltage is greater than 200 V All mean the same

  9. Surge or fault current (ISurge) • The amount of momentary overload current Isurge the diode can withstand without being destroyed • Temperature Range • Forward voltage drop (VF) • VF across the diode when it is conducting, given at the maximum average forward current • Maximum reverse current (IR,Max) • Maximum current IR the diode can handle for sustained period of time when operated as a Zener Diode • Other Parameters • Base diagram, total capacitance, reverse recovery time, recommended operating ranges

  10. Forward Characteristics ID breakdown voltage I F,Max PRV VD VF Reverse Characteristics IR,Max ~ ~ IS

  11. Forward Characteristics ID I F Rdyn=dV/dI Rd=VF/IF VD VF Reverse Characteristics

  12. Procedures: 1- Silicon Rectifier (IVT) Forward I-V at 21 C Forward I-V at ~45 C & ~70 C 2- Silicon Zener Diode (I-V) Forward I-V at 21 C Reverse I-V at 21 C 3- PSPICE Simulation (Bell 242)

  13. Components: • Silicon Rectifer (VBD < 200 V) • Si Diode (Zener, VBD ~ 27 V or ~ 12 V) • 0.1, 1.0, 4.7 kohms 2Watt Resistors • Heater Block & Tube Insulator • Temperature Probe • Variac (Shock Warning: Not Isolated From Power Line)

  14. DMM I + DMM V 10._ V - ID VD 1- Forward Characteristics of Diodes R Vary R from 100 k to 100

  15. R I + V 10.__V - Id [mA] Vd [V] 0.01 . . . 100 0.380 . . . 0.822 Vdc Rectifier & Zener R [ohm] Vdc [V] 10.38 . . . 10.822 100k . . . 100

  16. 2-Reverse Characteristics of Zener Diode(at voltages below breakdown) 4.7 k DMM I 1k + DMM 28V V 0-40V - ID VD

  17. VOLTS DUAL TRACKING + 20V V - + 20V 0-20V 1A COMMON 0-20V 1A V - 40V + +5@1A 20V V - DC CONSTANT-VOLTAGE CURRENT-LIMITED FLOATING POWER SUPPLY + -

  18. 1 k DMM I + DMM V 0-40V - ID VD 2-Reverse Characteristics of Zener diode (at breakdown region)

  19. 1 k DMM I + DMM V 0-40V - Id [A] Vd [V] Zener 0.1 . . . 9.9m 0.001 . . . 29.0

  20. 3- Simulation (PSPICE) D1 2 0 Diode .Model Diode D(IS=1E-14 RS=5 N=1 BV=25 IBV=1E-10) default: Unit: IS Saturation current 1.0E-14 A RS Ohmic resistance 0 Ohm N Emission Coefficient 1 - BV Reverse breakdown voltage infinite V IBV Current at breakdown voltage 1.0E-3 A ISR, NR, IKF, NBV, IBVL, NBVL, TT, CJO, VJ, M FC, EG, XTI, TIKF, TBV1, TBV2, TRS1, TRS2, KF, AF

  21. 5- Temperature Characteristics of Ge Diode Thermocouple Probe “Hot Block” Ceramic Tube Heaters Ge Diode to Variac 5 cm

  22. Temperature Probe switch Fluke Multimeter 200 mV range 1 mV/degree converter Box Probe

  23. Temperature Dependence of IS See Sedra/Smith, TABLE 3-1, p. 156 Insert expression for the intrinsic carrier concentration ni2 into the expression for the the saturation current IS IS = C1 X T3 X exp(-EG/kT) where C1 is a constant The T3temperature dependence is weak compared to the exponential temperature dependence so that IS = C2 X exp(-EG/kT) where C2 = C1 X 3003 lnIS = ln(C1 X 3003 ) - EG/kT

  24. Temperature Dependence of IS See Sedra/Smith, TABLE 3-1, p. 156 Insert expression for the intrinsic carrier concentration ni2 into the expression for the the saturation current IS IS = C1 X T3 X exp(-EG/kT) where C1 is a constant The T3temperature dependence is weak compared to the exponential temperature dependence so that IS = C2 X exp(-EG/kT) where C2 = C1 X 3003 lnIS = ln(C1 X 3003 ) - EG/kT

  25. Precautions: • Always turn off the Variac and set its dial to zero when not using it. • At the start of the lab period, preheat the “hot block” to 40C. When you get to part 5, insert the diode into the block and allow a few minutes for the temperature to stabilize. • Do not exceed a temperature of 75C in the “hot block.” • Do not exceed the current rating for the diode: • Ge: IF, Max = 100 mA I R,Max = 1.0 mA • Si: I F,Max = 100 mA I R,Max = 100 mA

  26. Must Submit Electronic Version Using Command submit ee312 E5ReportTuAM# Paper Version Also Required

  27. Team Writing • Abstract & Report for Zener Diode reverse IV on the 1999 web • Introduction to be provided or omitted • One Partner does silicon rectifier IVT results & discussion for IS & n • Must provide results in a computer file to Partner in less than one week & submit to EE 312 Staff using submit command.

  28. Other Partner uses information provided by partner to determine EG.Also include discussion and conclusions . Submit report electronically within one week of receiving partner’s contribution. Paper version also. • PSPICE Simulations Not Required. • Late penalties are -10 points per day and the day starts at 9:00 AM.

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