Off State Leakage of ADG201A-EP

Hi Shihab,

Thanks for the interest in our EP parts.  If you have a look at the regular ADG201A datasheet you will see a leakage plot.  Notice the log scale for leakage and as you increase in temperature the leakage increases. This is the dominant affect.  I don't have data for your conditions but my feeling is reducing the signal range may only have a minor effect in this case due to the high temperatures needed for EP parts. 

Have a look at the ADG1212-EP as an alternative.  It has much lower leakage levels. 

Regards,

Eric.

Hi Eric,

Thank you for the reply.

As per Digikey, Mouser this part (ADG1212SRU-EP-RL7) is " Scheduled for obsolescence and will be discontinued by the manufacturer". Do you have any other part which is recommended for New design(or in Production) which have leakage spec <30nA over operating temperature from -55C to 125C.

Thanks,

Shihab.

Hi Shihab,

Good point. I just double checked here on the ADG1212-EP obsolescence. There is a pin for pin compatible replacement planned that will be a Pb-free version "SRUZ-EP-RL7".  That will be a bit later in the year. So the ADG1212 may still be an option for you. 

As alternatives.  If you need a QUAD SPST. Here are two other options will low leakage that would be worth considering.

ADG5412F-EP

ADG613-EP (note this is a lower voltage switch)

I hope this helps.

Regards,

Eric.

Hi Eric,

I have downloaded the spice model of ADG1212 and tried some simulation. As per a basic simulation to check the leakage current ( channel to channel), I am getting large leakage currents. Following is the simulation circuit. Can you please explain why I am getting -187.5mV across R1. The leakage current seen into D1 is 1.875uA. As per datasheet the OFF Leakage over the operating temperature shall be no more than 1nA.

Thanks,

Shihab

Hi Shihab,

I agree with David, it seems that you are trying to short +5V and -5V (even with 10k resistors) in a single node, when the switch is turned on? Can you share more info about your application?

With regards to off leakage measurement, the setup above shows no connection to IN3, therefore switch 3 (S3 to D3) is not a valid off state. So current measured at R1 (which is connected to S3) is not a valid off leakage.

To measure off leakage see figure 21 in the ADG1212 data sheet as a reference.

Best Regards,

May

HI Shihab,

I do not understand your application here. In this setup by closing the switch you are going to short +5 V to -5 V. Is this what you are intending to do?

To measure leakage see figure 21 & 22 in the data sheet for the test setups as a reference.

Regards,

David

Hi David,

Thank you for the reply. Sorry for the mistake in the schematic. There should be 10kohm between P5V & D1 and N5V & S1. In this circuit I was expecting 0V across R1 but I am getting 186.8mV. Can you please explain the reason? Is it an IC spice model issue or is the simulation result I am getting is as per design?

Thanks,

Shihab.

Hi,

Thank you for the reply.

I cannot provide the actual circuit I am working with. But following is my application,

I have 4 sensor outputs. Each output is differential output. I have used resistor dividers in front of the Instrumentation Amplifier (INA )to attenuate the sensor signal. Each channel of Analog switch is connected across the INA inputs. During a fault condition an over voltage will occur across INA which will be seen at the output of INA and damage the ADC. So an over voltage detection circuit is used to short the INA inputs so that output will be zero and the ADC is protected during fault condition.

I have selected ADG1212 for this application because of its lowest leakage (1nA over -55C to 125C). But when I simulated the circuit I got leakage current which is in the range of uA. Also I do not want inter channel interference to happen. But as per my simulation, I see leakage current in uA range in other channels when they are not being used. Why I am not getting off state leakage <1nA as per datasheet?

Thanks,

Shihab.

Hi Shihab,

May I know how do you measure leakage?

As mentioned previously, the Multisim off leakage measurement on the figure above shows no connection to IN3, therefore switch 3 (S3 to D3) is not a valid off state. So current measured at R1 (which is connected to S3) is not a valid off leakage and is the reason why you are having uA measurement.

To measure leakage you may use the test setup below as a reference.

Let me know if this helps.

Best Regards,

May

Hi Shihab,

I can now understand the problem.

On the SPICE model, please put an asterisk sign (*) before RC1, RC2, and RC3. 

These resistors are the one causing the leakage.

Thank you for bringing this to our attention. We shall update the existing SPICE model.

Best Regards,

May