Jdec Standard

8/4/2019 Jdec Standard

1/13

JEDEC

STANDARD

Standard for Measuring Forward

Switching Characteristics ofSemiconductor Diodes

JESD286-B(Revision of EIA-286-A)

FEBRUARY 2000: Reaffirmed April 2005

ELECTRONIC INDUSTRIES ALLIANCE

JEDEC Solid State Technology Association


2/13

NOTICE

EIA/JEDEC standards and publications contain material that has been prepared, reviewed, and

approved through the JEDEC Board of Directors level and subsequently reviewed and approved by

the EIA General Counsel.

EIA/JEDEC standards and publications are designed to serve the public interest through eliminating

misunderstandings between manufacturers and purchasers, facilitating interchangeability and

improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay

the proper product for use by those other than JEDEC members, whether the standard is to be used

either domestically or internationally.

EIA/JEDEC standards and publications are adopted without regard to whether or not their adoption

may involve patents or articles, materials, or processes. By such action JEDEC does not assume any

liability to any patent owner, nor does it assume any obligation whatever to parties adopting the

EIA/JEDEC standards or publications.

The information included in EIA/JEDEC standards and publications represents a sound approach

to product specification and application, principally from the solid state device manufacturer

viewpoint. Within the JEDEC organization there are procedures whereby an EIA/JEDEC standard

or publication may be further processed and ultimately become an ANSI/EIA standard.

No claims to be in conformance with this standard may be made unless all requirements stated in the

standard are met.

Inquiries, comments, and suggestions relative to the content of this EIA/JEDEC standard or

publication should be addressed to JEDEC Solid State Technology Association, 2500 Wilson

Boulevard, Arlington, VA 22201-3834, (703)907-7560/7559 or www.jedec.org

Published by

ELECTRONIC INDUSTRIES ALLIANCE 1999


2500 Wilson Boulevard

Arlington, VA 22201-3834

This document may be downloaded free of charge, however EIA retains the

copyright on this material. By downloading this file the individual agrees not to

charge or resell the resulting material.

PRICE: Please refer to the current

Catalog of JEDEC Engineering Standards and Publications or call Global Engineering

Documents, USA and Canada (1-800-854-7179), International (303-397-7956)

Printed in the U.S.A.

All rights reserved


3/13

PLEASE!

DONT VIOLATE

THE

LAW!

This document is copyrighted by the Electronic Industries Alliance and may not be

reproduced without permission.

Organizations may obtain permission to reproduce a limited number of copies

through entering into a license agreement. For information, contact:


2500 Wilson Boulevard

Arlington, Virginia 22201-3834or call (703) 907-7559


4/13


5/13

JEDEC Standard No. 286-B

Page 1

STANDARD FOR MEASURING FORWARD SWITCHING CHARACTERISTICS OF

SEMICONDUCTOR DIODES

(From JEDEC Board Ballot JCB-99-13 formulated under the cognizance of JEDEC JC-22.4 Committee on

Signal and Regulator Diodes.)

1 Forward switching characteristics

When a step function of forward current (high di/dt) is applied to a signal or switching diode (typically

rated less than 400 mA and less than 150 volts), the carrier gradient does not develop immediately,

resulting in an overshoot voltage that decreases with time to the dc static level. The diode appears to be

inductive; however, transit time and conductivity modulation, not inductance, are responsible for the

effect. The result is an overshoot voltage that decays to 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. In these circuits, the transit time and

modulation result in delayed conduction of forward current instead of the forward recovery response noted

above. 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 forward switching phenomenon.

Since the circuits that exhibit such behavior are different in observed response, one must use different test

methods; both are given in this Standard.

2 Forward recovery

Forward Recovery Time, (tfr), is the time interval between the instant when the forward voltage rises

through a specified first value, usually 10% of its final value, and the instant when it falls from its peak

value, VFRM, to a specified low second value, vFR, upon the application of a step current following a zero

voltage or a specified reverse voltage condition.

Peak forward recovery voltage, VFRM, is the maximum instantaneous value across the DUT resulting from

the application of a specified step function of forward current. This characteristic is sometimes referred to

as modulation voltage. Also VF(pk), VFM(DYN), and VFM are sometimes used, but VFRM is preferred.

2.1 Procedure

The DUT is subjected to a specified step function of forward current. The resulting current waveformthrough the device and voltage waveform across the device are graphically monitored with amplitude

displayed versus time. The desired characteristics are obtained from the display.


6/13


Page 2

2 Forward recovery (contd)

2.2 Test circuit and waveform

The 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 the

nature of the source requires an internal switch, devices such as a mercury switch, power MOSFET or

similar devices may be used. Compliance voltage (open circuit output voltage) of the pulse current source

shall be a minimum 3 VFRM. In any event, the combination must provide the specified conditions of the

pulse to the DUT.

Aberrations of the pulse top shall not exceed +10% of IF. The di/dt of the leading edge shall be measured

between the 10% and 90% amplitude points.

R is a noninductive shunt or current-viewing calibrated resistor. A suitable high frequency current probe

may be used instead. The external switch shown is electronic and is left open if no reverse voltage isspecified; otherwise it is synchronized to be open only for the duration of the current pulse. For these

devices; switching from a reverse bias instead of zero bias usually does not significantly affect the accuracy

of the forward recovery measurement.

It is expedient to observe the waveforms on a suitable dual-channel oscilloscope. The common connection

shown will result in the inversion of the current waveform. Most oscilloscopes provide an inverted display

switch to yield the waveforms as shown.

2.3 Test conditions to be specified

a. Rise time of current pulse (measured from 10% to 90% of IFM), tr = _____Fs

b. Peak forward current, IF = ______A

c. Forward recovery voltage defining the end of the forward recovery time, if different from 1.1 times

VF, vFR = ___V. See notes for guidelines.

d. Test current pulse duration, tp = _____s

e. Test repetition rate, f = _____pps (1000 max)

f. Reverse voltage prior to application of current pulse, VR = _____V

g. Case temperature, TC = _____o

Cor

Lead temperature, TL = _____oC


7/13


Page 3


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/W

NOTES

1 If VFRM is expected to exceed 10 V, select vFM = 3 times the expected value of VF.

2 If VFRM is expected to be less than 1.3 V, select vFR = 0.5 (VFRM - VF) + VF

2.4 Characteristics to be measured

a. Forward recovery time, tfr = _____s

b. Peak forward recovery voltage, VFRM = _____V

c. DC forward voltage, VF = _____V

To oscilloscopechannel B

DUT

To oscilloscopechannel A(inverted)

R

vRCurrentpulse

source

Switch

+

-

+

-

Figure 1 Forward switching characteristics test circuit


8/13


Page 4


2.4 Characteristics to be measured (contd)

Channel Btfr

0.1VF

VFRMvFR(1.1VF unless otherwise specified)

V

VF

VR

Channel Btfr

0.1VF

VFRMvFR(1.1VF unless otherwise specified)

V

VF

Channel A

tr

0.9|FM

I0.9IFM

0.1|FM

tp

IFM

Figure 2 Forward switching characteristics waveforms


9/13


Page 5

3 Forward turn-on-time

The forward turn-on time (ton) is defined as the time required for the forward current of the diode to reach

90% of its final predetermined value, when the diode is switched from zero to forward bias. If the diode is

switched 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 Procedure

The forward turn-on time may be measured by observing the forward current waveform on an oscilloscope

in response to a square wave which switches the diode from zero or reverse bias to forward bias. A circuit

which can be used for this test is shown in Figure 3. The waveforms which are generally observed are

shown in Figure 4 or Figure 5.

3.2 Circuit description and requirements

DUT

OscilloscopeRL

Voltagepulse

source

+

-

RS

VIN

Rs = Source output resistance

RL = Load Resistance

Figure 3 Forward turn-on time test circuit


10/13


Page 6

3 Forward turn-on-time (contd)

3.3 Requirements of circuit components (refer to Figure 3 for symbols)

When the diode is replaced by a short circuit, the response time from zero to 90% of IF

shall be less than

10% of the specified ton maximum 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 input

voltage pulse; 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 ton maximum for the device being

tested.

The duty factor of the voltage pulse shall be low enough so that negligible heating occurs.

The load resistor, RL, should be chosen such that RL + RG = 100 ohms, unless otherwise specified.

3.4 Calibration procedure

Insert a diode representation of the diodes to be tested into the test clips and adjust V IN and RL until the

desired steady-state forward current (IF) has been obtained.

,LR

FVINV

FI

= where VF = forward voltage of the diode at IF.

If the forward voltage of the diode varies considerably from diode to diode, a slight adjustment of VIN may

be required to maintain IF constant for each diode.

Adjust the oscilloscope to the proper ranges for observing the turn-on time and the amplitude of IF. The

total sweep time of the oscilloscope should be at least twice the measured turn-on time when establishing

the amplitude of IF (steady-state). This will aid in determining the 90% IF point. The deflection due to IFshould be at least 1/2 full scale of the detector.

3.5 Measurement

If the diode is switched from zero to a forward bias state, a current waveform similar to Figure 4 should be

displayed on the oscilloscope. The forward turn-on time (ton) is measured by determining the time required

for 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 the forward bias state, a current waveform similar to

Figure 5 should be displayed on the oscilloscope. The forward turn-on time (ton) is measured by

determining the time required for the forward current to increase from zero to 90% of its final value. This

is shown graphically in Figure 5.


11/13


Page 7


3.5 Measurement (contd)

0.9IF

IF

ton

VIN

Time

Diode forward current

mplitude

0

See Note on page 8

Figure 4 Current and voltage waveforms for ton measurement with no initial reverse bias


12/13


Page 8


3.5 Measurement (contd)

0.9IFIF

ton Time

0

See

Note

mplitude

VR

t

VIN

Figure 5 Current and voltage waveforms for ton measurement with initial reverse bias

NOTE Although in Figures 4 and 5, current and voltage cross the zero axis at slightly different

points, this difference does not significantly affect the accuracy of the measurement.


13/13