Diode leakage current measurement

Anish N

Other Parts Discussed in Thread: INA121

Hi,

I need to measure the diode leakage current through the diode D1 which will be in uA. Please see the attached picture, which is a sealed relay with 5 terminations.

Please guide through if there is any application circuits.

Regards,

Anish

over 11 years ago

0 Wade Vonbergen over 11 years ago

TI__Guru 62930 points

Anish,
What is the product you are trying to test? I can move it to the correct forum.
Regards,
Wade

0 Anish N over 11 years ago in reply to Wade Vonbergen

Intellectual 340 points

Wade,

Thank you for your response.

Product is an electromechanical sealed relay used in aerospace applications.

We are in to a development of an testing station for the measurement of the relay parameters. Diode leakage current is a parameter among them.

Kindly help.

Regards.

Anish

0 Wade Vonbergen over 11 years ago in reply to Anish N

TI__Guru 62930 points

Anish,

Unfortunately, we do not make test equipment.

The High reliability group has semiconductor products for defense and aerospace.

A test fixture connected to a external source/meter seems like a logical solution.

Regards,

Wade

0 Anish N over 11 years ago in reply to Wade Vonbergen

Intellectual 340 points

Wade,

Actually we are into the development of testing equipment for the purpose mentioned. But we are unable to measure the leakage current which is in the order of uA. We are looking for any application circuit or something like that. Kindly help if there is any.

Regards,

Anish

0 Wade Vonbergen over 11 years ago in reply to Anish N

TI__Guru 62930 points

Anish, I am not familiar with very low current sensing topologies or methods.
I will move your post to the precision amplifier forum. Possibly they will have some solutions.
Regards,
Wade

0 Anish N over 11 years ago in reply to Wade Vonbergen

Intellectual 340 points

Wade,

Thank you.

Regards,

Anish N

0 Pete%20Semig over 11 years ago in reply to Anish N

TI__Mastermind 25865 points

Hello,

You can place a resistor in series with the Termination 2 (aka shunt resistor, or Rsh) and then use a low input-bias current instrumentation amplifier (e.g. INA121) to amplify the voltage across the resistor. You will need to make the shunt resistor large enough such that the voltage developed across it due to the diode leakage exceeds the offset voltage of the instrumentation amplifier. Also, I'm unsure of the common-mode voltage of Termination 2. Please be aware that the output swing of the instrumentation amplifier depends on Vcm, Vref, and the supply voltages.

I have a number of resources that you may find useful. Unfortunately there is a temporary issue with our forums that prevents me from providing you with the direct links. Therefore, please try searching the web for "A Current Sensing Tutorial" and "EETimes". It is a 4 part series that discusses selecting devices and sizing the shunt resistor (among many other things).

Also, there is a series that EDN published. Try searching the web for "Vcm vs. Vout" and "EDN". It is a 3 part series that discusses the relationship between Vout and Vcm, gain, Vref, and the power supplies.

0 Anish N over 11 years ago in reply to Pete%20Semig

Intellectual 340 points

Hello Pete Semig,

Extremely thank you for the information's. Please share the direct links once you can.

Thanks and Regards.

Anish N

0 Pete%20Semig over 11 years ago in reply to Anish N

TI__Mastermind 25865 points

Hello Anish,

As a workaround, I pasted the links in a PDF file. Please see attachment.

Links.pdf

0 Anish N over 11 years ago in reply to Pete%20Semig

Intellectual 340 points

Hello Pete,

Thank you

Regards,

Anish N

0 Anish N over 11 years ago in reply to Anish N

Intellectual 340 points

Hello Pete,

Can you please suggest a Current shunt monitor with analog output with the specification as follows:

Shunt current to be measured - 0 to 330 mA
Range of voltage through shunt - 0 to 50 V
Analog output needed - 0 to 3.3 V

Shunt Current is bidirectional

Please help.

Regards,
Anish

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Diode leakage current measurement