AN1006
Application Notes
6. Set Rate by depressing Norm.
7. Set Step Family by depressing Rep (repetitive).
8. Set Mode to DC.
3. Set Max Peak Volts to 75 V. (80 V on 370)
4. Set Mode to DC.
5. Set Horizontal knob to Step Generator.
9. Set Horizontal knob to 0.5 V/DIV.
10. Set Power Dissipation to 220 W (100 W on 577).
11. Set Number of Steps to 1. (Set steps to 0 (zero) on 370.)
6. Set Vertical knob to approximately 10 percent of the maxi-
mum I specified.
H
Note: Due to large variation of holding current values, the
scale may have to be adjusted to observe holding current.
7. Set Number of Steps to 1.
12. Set Vertical knob to a sufficient setting to allow the viewing
of 2 times the IT(RMS) rating of the device (IT(peak)) on CRT.
8. Set Offset by depressing 0 (zero). (Press Aid and Oppose at
Before continuing with testing, note the following:
the same time on 370.)
(1) Due to the excessive amount of power that can be
generated in this test, only parts with an IT(RMS) rating
of 6 A or less should be tested on standard curve
tracer. If testing devices above 6 A, a Tektronix model
176 high-current module is required.
9. Set Step/Offset Amplitude to twice the maximum IGT of the
device.
10. Set Terminal Selector to Step Generator-Emitter Grounded.
11. Set Step Family by depressing Single.
(2) A Kelvin test fixture is required for this test. If a
12. Set Left-Right Terminal Jack Selector to correspond with
Kelvin fixture is not used, an error in measurement of
location of test fixture.
V
TM will result due to voltage drop in the fixture. If a
Kelvin fixture is not available, Figure AN1006.3 shows
necessary information to wire a test fixture with
Kelvin connectors.
13. Increase Variable Collector Supply Voltage to maximum
position (100).
14. Set Step Family by depressing Single. (This could possibly
cause the dot on CRT to disappear, depending on the verti-
cal scale selected.)
13. Set Left-Right Terminal Jack Selector to correspond with
the location of the test fixture.
14. Increase Variable Collector Supply Voltage until current
reaches rated IT(peak), which is twice the IT(RMS) rating of the-
SCR under test.
15. Change Terminal Selector from Step Generator-Emitter
Grounded to Open Base-Emitter Grounded.
16. Decrease Variable Collector Supply Voltage to the point
where the line on the CRT changes to a dot. The position of
the beginning point of the line, just before the line becomes a
dot, represents the holding current value. (Figure AN1006.8)
Note: Model 370 current is limited to 10 A.
WARNING: Limit test time to 15 seconds maximum after the
Variable Collector Supply has been set to IT(peak), After the
Variable Collector Supply Voltage has been set to IT(peak), the
test time can automatically be shortened by changing Step
Family from repetitive to single by depressing the Single
button.
To measure VTM, follow along horizontal scale to the point where
the trace crosses the IT(peak) value. The distance from the left-
hand side of scale to the intersection point is the VTM value.
(Figure AN1006.7)
PER
V
500
E
R
A
T
DIV
PER
H
O
R
I
Z
DIV
PER
S
T
E
P
PER
V
2
E
R
A
T
()k
DIV
9m
PER
DIV
I
DIV
H
PER
H
V
TM
O
R
I
500
mV
Figure AN1006.8 IH = 1.2 mA
Z
DIV
Procedure 6: IGT and VGT
To measure the IGT and VGT parameter:
1. Set Polarity to (+).
2. Set Number of Steps to 1.
3. Set Offset by depressing Aid.
PER
S
100
mA
T
E
P
I
PK
()k
DIV
9m
PER
DIV
20
4. Set Offset Multiplier to 0 (zero). (Press Aid and Oppose at
Figure AN1006.7 VTM = 1.15 V at IT(peak) = 12 A
the same time on 370.)
Procedure 5: IH
To measure the IH parameter:
1. Set Polarity to (+).
2. Set Power Dissipation to 2.2 W. (2 W on 370)
5. Set Terminal Selector to Step Generator-Emitter Grounded.
6. Set Mode to Norm.
7. Set Max Peak Volts to 15 V. (16 V on 370)
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AN1006 - 6
©2002 Teccor Electronics
Thyristor Product Catalog
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