I found a breakdown meter once that ramped up the voltage until a certain current limit was reached. For this one, it was 100uA. If we need to be more careful, we can go 10uA.
Lumba, may you live long and prosper.
- keantoken
Bump...
I've got about 100 VP0106N5 P channel FETs from Supertex back in the 80s. I'd like to screen them for 70V operation so I figure I need at least 80V BVdss. Since this FET was screened for 90V, 60V and 40V grades I figure there is a fair chance I'll get some with higher breakdown than specified. The data sheet calls out Idss of -10uA Vgs=0V, Vds=max rating.
From this it appears I need to use an 8Meg resistor and ramp the drain voltage to -80V while tying the gate to source and measure the voltage at the drain. If it goes to 80V there is no breakdown and the device passes 80V.
What I can't find is information that relates VBdss to temperature so I can be sure the parts will work when they get warm or start cold.
I've got about 100 VP0106N5 P channel FETs from Supertex back in the 80s. I'd like to screen them for 70V operation so I figure I need at least 80V BVdss. Since this FET was screened for 90V, 60V and 40V grades I figure there is a fair chance I'll get some with higher breakdown than specified. The data sheet calls out Idss of -10uA Vgs=0V, Vds=max rating.
From this it appears I need to use an 8Meg resistor and ramp the drain voltage to -80V while tying the gate to source and measure the voltage at the drain. If it goes to 80V there is no breakdown and the device passes 80V.
What I can't find is information that relates VBdss to temperature so I can be sure the parts will work when they get warm or start cold.
I found the data sheet here: VP0106N3 pdf, VP0106N3 description, VP0106N3 datasheets, VP0106N3 view ::: ALLDATASHEET :::
It show the normalized Vdss changes from .95 at - 50 C to 1.07 at 150 C. If that is true, that's pretty good,
It show the normalized Vdss changes from .95 at - 50 C to 1.07 at 150 C. If that is true, that's pretty good,
Thanks.
It is great that the tempco is positive so I can test at room temp and derate by 2% to 0ºC and should be safe knowing VBdss will go up as the part warms up and I will never be using the circuit below 10ºC.
Strange that the graph does not cross 100% at 25ºC since that is the temp called out in the data table earlier in the data sheet.
Also the N3 (TO-92) has VBdss specified at 1mA and the data sheet on the N5 (TO-220) has BVdss specified at 10uA.
It is great that the tempco is positive so I can test at room temp and derate by 2% to 0ºC and should be safe knowing VBdss will go up as the part warms up and I will never be using the circuit below 10ºC.
Strange that the graph does not cross 100% at 25ºC since that is the temp called out in the data table earlier in the data sheet.
Also the N3 (TO-92) has VBdss specified at 1mA and the data sheet on the N5 (TO-220) has BVdss specified at 10uA.
I built this curve tracer. It only goes to 10 volts and I think 100mA. The software links in the Elektor article don't work. Took several hours to solve that part. HFE readings are questionable, but it works well for matching and showing multiple curves at varied current.
Ken
I'm a little perplexed.
I set up a test set with a socket to test the FET. Gate and Source were tied together to the Power supply +, drain terminal was connected to a 10M resistor and a 100K resistor in series. One meter measured G/S to D voltage and a second measured the voltage across the 100K resistor. (100K sense resistor so the input resistance of the meter did not effect the measurement significantly.)
I increased the voltage on the supply until the voltage on the sense resistor was 1V which corresponded to 10uA, and measured the voltage on the Source/Gate to Drain, and I got 102V.
What confuses me is I did not see a sudden increase in current, but rather a gradual increase as if there were no breakdown. I expected to see a sudden drop in G/S to D voltage and corresponding increase in voltage across the 10M resistor.
Have I done this wrong? Or am I expecting the wrong results/testing wrong?
Never mind.
I found one that at 10uA it only had 51V G/S to D so I experimented. 10uA is at the start of the knee of the curve and if I increase the voltage supply beyond this point the voltage across the FET does not increase as rapidly as the voltage across the sense resistor (hence the current) and it rapidly reaches a point where Vg/s-d hardly increases at all.
I set up a test set with a socket to test the FET. Gate and Source were tied together to the Power supply +, drain terminal was connected to a 10M resistor and a 100K resistor in series. One meter measured G/S to D voltage and a second measured the voltage across the 100K resistor. (100K sense resistor so the input resistance of the meter did not effect the measurement significantly.)
I increased the voltage on the supply until the voltage on the sense resistor was 1V which corresponded to 10uA, and measured the voltage on the Source/Gate to Drain, and I got 102V.
What confuses me is I did not see a sudden increase in current, but rather a gradual increase as if there were no breakdown. I expected to see a sudden drop in G/S to D voltage and corresponding increase in voltage across the 10M resistor.
Have I done this wrong? Or am I expecting the wrong results/testing wrong?
Never mind.
I found one that at 10uA it only had 51V G/S to D so I experimented. 10uA is at the start of the knee of the curve and if I increase the voltage supply beyond this point the voltage across the FET does not increase as rapidly as the voltage across the sense resistor (hence the current) and it rapidly reaches a point where Vg/s-d hardly increases at all.
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