1、JEDECSTANDARDStandard for Measuring ForwardSwitching Characteristics ofSemiconductor DiodesJESD286-B(Revision of EIA-286-A)FEBRUARY 2000: Reaffirmed April 2005ELECTRONIC INDUSTRIES ALLIANCEJEDEC Solid State Technology AssociationNOTICEEIA/JEDEC standards and publications contain material that has be
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5、rmation included in EIA/JEDEC standards and publications represents a sound approachto product specification and application, principally from the solid state device manufacturerviewpoint. Within the JEDEC organization there are procedures whereby an EIA/JEDEC standardor publication may be further p
6、rocessed and ultimately become an ANSI/EIA standard.No claims to be in conformance with this standard may be made unless all requirements stated in thestandard are met.Inquiries, comments, and suggestions relative to the content of this EIA/JEDEC standard orpublication should be addressed to JEDEC S
7、olid State Technology Association, 2500 WilsonBoulevard, Arlington, VA 22201-3834, (703)907-7560/7559 or www.jedec.orgPublished byELECTRONIC INDUSTRIES ALLIANCE 1999JEDEC Solid State Technology Association2500 Wilson BoulevardArlington, VA 22201-3834This document may be downloaded free of charge, ho
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9、, International (303-397-7956)Printed in the U.S.A.All rights reservedPLEASE!DON”T VIOLATETHELAW!This document is copyrighted by the Electronic Industries Alliance and may not bereproduced without permission.Organizations may obtain permission to reproduce a limited number of copiesthrough entering
10、into a license agreement. For information, contact:JEDEC Solid State Technology Association2500 Wilson BoulevardArlington, Virginia 22201-3834or call (703) 907-7559JEDEC Standard No. 286-BPage 1STANDARD FOR MEASURING FORWARD SWITCHING CHARACTERISTICS OFSEMICONDUCTOR DIODES(From JEDEC Board Ballot JC
11、B-99-13 formulated under the cognizance of JEDEC JC-22.4 Committee onSignal and Regulator Diodes.)1 Forward switching characteristicsWhen a step function of forward current (high di/dt) is applied to a signal or switching diode (typicallyrated less than 400 mA and less than 150 volts), the carrier g
12、radient does not develop immediately,resulting in an overshoot voltage that decreases with time to the dc static level. The diode appears to beinductive; however, transit time and conductivity modulation, not inductance, are responsible for theeffect. The result is an overshoot voltage that decays t
13、o the normal forward voltage in a measurable time. This phenomenon is called forward recovery as described in Section 2 of this Standard.Forward current-time characteristics are sometimes considered in respect to propagation delay from diodesin low-impedance, low-voltage, high-speed signal circuits.
14、 In these circuits, the transit time andmodulation result in delayed conduction of forward current instead of the forward recovery response notedabove. This behavior relates to turn-on time as described in Section 3 of this Standard.Both the voltage overshoot and delayed conduction are from the same
15、 forward switching phenomenon. Since the circuits that exhibit such behavior are different in observed response, one must use different testmethods; both are given in this Standard.2 Forward recoveryForward Recovery Time, (tfr), is the time interval between the instant when the forward voltage rises
16、through a specified first value, usually 10% of its final value, and the instant when it falls from its peakvalue, VFRM, to a specified low second value, vFR, upon the application of a step current following a zerovoltage or a specified reverse voltage condition.Peak forward recovery voltage, VFRM,
17、is the maximum instantaneous value across the DUT resulting fromthe application of a specified step function of forward current. This characteristic is sometimes referred toas modulation voltage. Also VF(pk), VFM(DYN), and VFMare sometimes used, but VFRMis preferred.2.1 ProcedureThe DUT is subjected
18、 to a specified step function of forward current. The resulting current waveformthrough the device and voltage waveform across the device are graphically monitored with amplitudedisplayed versus time. The desired characteristics are obtained from the display.JEDEC Standard No. 286-BPage 22 Forward r
19、ecovery (contd)2.2 Test circuit and waveformThe general test circuit is shown in Figure 1 and the waveforms in Figure 2.The current pulse source may be a pulse generator, charged line, pulse-forming network, or the like. If thenature of the source requires an internal switch, devices such as a mercu
20、ry switch, power MOSFET orsimilar devices may be used. Compliance voltage (open circuit output voltage) of the pulse current sourceshall be a minimum 3 VFRM. In any event, the combination must provide the specified conditions of thepulse to the DUT.Aberrations of the pulse top shall not exceed +10%
21、of IF. The di/dt of the leading edge shall be measuredbetween the 10% and 90% amplitude points.R is a noninductive shunt or current-viewing calibrated resistor. A suitable high frequency current probemay be used instead. The external switch shown is electronic and is left open if no reverse voltage
22、isspecified; otherwise it is synchronized to be open only for the duration of the current pulse. For thesedevices; switching from a reverse bias instead of zero bias usually does not significantly affect the accuracyof the forward recovery measurement.It is expedient to observe the waveforms on a su
23、itable dual-channel oscilloscope. The common connectionshown will result in the inversion of the current waveform. Most oscilloscopes provide an inverted displayswitch to yield the waveforms as shown.2.3 Test conditions to be specifieda. Rise time of current pulse (measured from 10% to 90% of IFM),
24、tr= _Fsb. Peak forward current, IF= _Ac. Forward recovery voltage defining the end of the forward recovery time, if different from 1.1 timesVF, vFR= _V. See notes for guidelines.d. Test current pulse duration, tp= _se. Test repetition rate, f = _pps (1000 max)f. Reverse voltage prior to application
25、of current pulse, VR= _Vg. Case temperature, TC= _oCorLead temperature, TL= _oCJEDEC Standard No. 286-BPage 32 Forward recovery (contd)2.3 Test conditions to be specified (contd)h. Maximum thermal resistance of heat dissipator upon which the DUT is to be mounted, Rth= _oC/WNOTES1 If VFRMis expected
26、to exceed 10 V, select vFM= 3 times the expected value of VF.2 If VFRMis expected to be less than 1.3 V, select vFR= 0.5 (VFRM- VF) + VF2.4 Characteristics to be measureda. Forward recovery time, tfr= _sb. Peak forward recovery voltage, VFRM= _Vc. DC forward voltage, VF= _VTo oscilloscopechannel BDU
27、TTo oscilloscopechannel A(inverted)RvRCurrentpulsesourceSwitch+-+-Figure 1 Forward switching characteristics test circuitJEDEC Standard No. 286-BPage 42 Forward recovery (contd)2.4 Characteristics to be measured (contd)Channel Btfr0.1VFVFRMvFR(1.1VFunless otherwise specified)VVFVRChannel Btfr0.1VFVF
28、RMvFR(1.1VFunless otherwise specified)VVFChannel Atr0.9|FMI0.9IFM0.1|FMtpIFMFigure 2 Forward switching characteristics waveformsJEDEC Standard No. 286-BPage 53 Forward turn-on-timeThe forward turn-on time (ton) is defined as the time required for the forward current of the diode to reach90% of its f
29、inal predetermined value, when the diode is switched from zero to forward bias. If the diode isswitched from a reverse bias state to a forward bias, the forward turn-on time (ton) is measured from thetime the current crosses zero to 90% of its final predetermined value.3.1 ProcedureThe forward turn-
30、on time may be measured by observing the forward current waveform on an oscilloscopein response to a square wave which switches the diode from zero or reverse bias to forward bias. A circuitwhich can be used for this test is shown in Figure 3. The waveforms which are generally observed areshown in F
31、igure 4 or Figure 5.3.2 Circuit description and requirementsDUTOscilloscopeRLVoltagepulsesource+-RSVINRs= Source output resistanceRL= Load ResistanceFigure 3 Forward turn-on time test circuitJEDEC Standard No. 286-BPage 63 Forward turn-on-time (contd)3.3 Requirements of circuit components (refer to
32、Figure 3 for symbols)When the diode is replaced by a short circuit, the response time from zero to 90% of IFshall be less than10% of the specified tonmaximum of the diode being tested.If the above conditions cannot be met, the turn-on time will be a function of the rise time of the inputvoltage puls
33、e; thus the rise time of the input pulse must be specified.The duration of the input voltage pulse shall be at least 10 times the tonmaximum for the device beingtested.The duty factor of the voltage pulse shall be low enough so that negligible heating occurs.The load resistor, RL, should be chosen s
34、uch that RL+ RG= 100 ohms, unless otherwise specified.3.4 Calibration procedureInsert a diode representation of the diodes to be tested into the test clips and adjust VINand RLuntil thedesired steady-state forward current (IF) has been obtained.,LRFVINVFI= where VF= forward voltage of the diode at I
35、F.If the forward voltage of the diode varies considerably from diode to diode, a slight adjustment of VINmaybe required to maintain IFconstant for each diode.Adjust the oscilloscope to the proper ranges for observing the turn-on time and the amplitude of IF. Thetotal sweep time of the oscilloscope s
36、hould be at least twice the measured turn-on time when establishingthe amplitude of IF(steady-state). This will aid in determining the 90% IFpoint. The deflection due to IFshould be at least 1/2 full scale of the detector.3.5 MeasurementIf the diode is switched from zero to a forward bias state, a c
37、urrent waveform similar to Figure 4 should bedisplayed on the oscilloscope. The forward turn-on time (ton) is measured by determining the time requiredfor the forward current to reach 90% of its final value. This is shown graphically in Figure 4.If the diode is switched from a reverse bias state to
38、the forward bias state, a current waveform similar toFigure 5 should be displayed on the oscilloscope. The forward turn-on time (ton) is measured bydetermining the time required for the forward current to increase from zero to 90% of its final value. Thisis shown graphically in Figure 5.JEDEC Standa
39、rd No. 286-BPage 73 Forward turn-on-time (contd)3.5 Measurement (contd)0.9IFIFtonVINTimeDiode forward currentAmplitude0See Note on page 8Figure 4 Current and voltage waveforms for tonmeasurement with no initial reverse biasJEDEC Standard No. 286-BPage 83 Forward turn-on-time (contd)3.5 Measurement (
40、contd)0.9IFIFton Time0SeeNoteAmplitudeVRtVINFigure 5 Current and voltage waveforms for tonmeasurement with initial reverse biasNOTE Although in Figures 4 and 5, current and voltage cross the zero axis at slightly differentpoints, this difference does not significantly affect the accuracy of the measurement.
