TS12A44514: Test setup to measure Input leakage current

Hi Takashi,

Leakage current is measure in two different ways, depending on what leakage current you are testing. 

If you are measuring Off Leakage current the switch is open. To measure Off current they attach a voltage source on both terminals of the channel and then they measure the current on both sides. The datasheet for the TS12A44514 doesn't show the test setup, however this test doesn't change much from part to part, the only thing that changes is how many terminals to use. 

So the test setup would be similar to this, except for a 1:1 configuration:

For on leakage current the setup changes to one in which the switch is closed, and the pin opposite the source is left floating, which when the switch is on will make Vd ~ Vs. Then they measure the current the device is pulling in this setup. Once again, this datasheet doesn't show the test setup but other datasheets do, so here is another example of what the test setup would look like, just remember that the configuration on the drawing is different than the actual part.

For other pins in these tests I would recommend the following:

Off Leakage:

Vcc = Vcc

Gnd = Gnd

INx = Gnd

On Leakage:

Vcc = Vcc

Gnd = Gnd

INx = Vdd (x is the channel you are testing for leakage)

Also make sure that you follow the test conditions listed in the datasheet shown below, highlighted in yellow:

Also for a quick run-down of leakage current in our Mux's we have a precision lab video here

Best Regards,

Parker Dodson

Hi Takashi,

For your first question: There may be a small increase, but it shouldn't be large. The majority of off leakage comes from the ESD diodes connected to the NO/NC/COM ports, so the other ports shouldn't have an effect because they aren't electrically connected, but there might be some small increase, but this would be negligible compared to the other sources of leakage.

For your second question: No this shouldn't cause major upticks in leakage current. The majority of leakage is coming from the ESD diodes; this leakage is based on the reverse voltage level of a diode Vd = V_com/NC/NO - VDD. The higher this value is the higher the current, but the biggest contributing factor to diode leakage is temperature. The reasons I believe that this shouldn't cause an issue is because we still see the same spec's for a 12V supply, with different test conditions as shown below:

With that being said though The test conditions where Vcom is > than VNo/VNC should produce a smaller leakage current because that will lower the amount of reverse bias voltage on the ESD diodes, even though this reduction is most likely negligible.

I am unsure exactly what is causing the problems in your customer's system, but I'd love to help, if you can provide my the following information so I can see what we can do to get this project fixed.

What levels are you seeing in your customers system? I.e. what is the supply you are using, what are the test conditions for the board (including operating temp), how your customer is measuring leakage current, and what is the leakage current you are measuring?