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INA196A-Q1: date codes

Part Number: INA196A-Q1
Other Parts Discussed in Thread: INA193, INA196

Hi,

I would like to check with you what are the differences in these date  codes.

We got an old part from our US factory, unfortunately  I was unable to capture it. But the current failures I am getting is above the spec limit of 0-50mA.

The part we are currently using shown below came from China facility as per communication with the distributor. Anyway you can help us on these?

  

 

  • Hello Nomer,

    Thanks for reaching out on the forum.   Its difficult to see clearly from your pictures, but I assume the dashes on the upper left photo look the ones I made on the image below.  If that is correct, the fabrication date for that would be June 2011.  As for the bottom, you are correct, the date is July 2008.

  • Are there any differences with the old vs the latest parts? The old date codes pass on our application while the batches we are currently buying are 50% failing in our test specifications of 0-50mA range. the old date codes can measure 4-5mA while in the 2011 batches, 40% is close to the high limit of 50mA. 10% were in between 0-50mA spec.
  • Hello Nomer,

    Could you tell us what your shunt resistor value is?  If you are trying to measure currents that generate a vsense below 20mV, you are outside of the regions defined in the datasheet and may encounter various errors.  There is good FAQ on the topic here.  Even though the linked thread talks about the INA193, this linked thread also applies to the INA196.

    If your vsense is above 20mV for these failures we would like to know which distributor you purchased the devices from and when.  Also would you be able to provide us with a schematic so we can better understand your operating conditions.

  • Hi Patrick,

    Bus Test (Sequential)

    Closes MUX channel for the board being tested to connect load.

    Turns all buses off and closes relay.For each: upper bus, lower bus, filter bus, battery relay:

    Turn off bus and read current and voltage:

    Turn on bus and read current and voltage:

     

    Battery voltage = 20V

    Sub bus voltage = 20V

    Returned data variables:

               

                <Bus> Off Voltage (V):

                            Limits: Low: 0.0 V

                                        High: 2.0 V

     

                <Bus> Off Current (mA):

                            Limits: Low: 0.0 mA

                                        High: 50.0 mA

     

                <Bus> On Voltage (V):

                            Limits: Low: 18.0 V

                                        High: 21.0 V

     

                <Bus> On Current (mA):

                            Limits: Low: 0.0 mA

                                        High: 50.0 mA

  • Hello Nomer,

    I need to clarify a few things. You say that some of these devices can measure 4-5mA. Based on your max shunt value of 50mΩ, that means your vsense is 0.005mA*0.05Ω=250uV at most. This is well under the 20mV we specify for the minimum operating condition. Even at 50mA you are still below the required minimum for using this device. If you are trying to measure these current levels, you will need to increase you shunt resistor such that the minimum Vsense voltage is 20mV.

    If you are not intending to measure this current, and the 4-50mA is something you see when you are cutting the voltage to the bus pins off. One possible explanation for why the current still may be in the mA is your inductor L3.
  • Sorry 4-5mA is measured at the output. Iload should be around 2A for bus and 3A for Battery which gives 99mV and 100mV respectively. Rsh_max = (Vout / GAIN)/ Iload_max. Above the vsense = 20mV where vsense = Rsh*Iload_max

    So it means when the relay switches off,  the energy from the inductor L3 is released back into the U20. I'm seeing some voltage spikes across the Rsh when the relay switches off. Not sure if the component can handle the flyback effect. Maybe make adjustments on the test timing or add a flyback diode across L3. But why is it ok with the old date codes and those 2011 date codes fail.

    For the bus currents, is it the same thing? I will check the load connections.

  • Hello Nomer,

    If I understand correctly, you are saying that when 2A or 3A is going across your shunt the output is really low (~2.6mV to 5mV), making it seem as though the device is only reading 4-5mA. If that is the case, you may have damaged the part, which may have been caused by those voltage spikes you saw.
  • There is also a via hole on the trace connecting the VIN+ and VIN_ to the Rsense. Will the Vos be affected by the via hole impedance? Previously you also asked about the distributor. We got it from Arrowasia. but we also bought from mouser. 50% are out of our specs. I will also try increasing the Rshunt as per your advise. hopefully this solves the offset.

  • Hello Nomer,

    So you are saying that on the trace between your rshunt and the INA196 is a via? I do not think that the via hole impedance would have a large impact on your Vos. However, if the traces between rshunt and INA196 are very long and not well matched in length, then I suspect the offset and gain may be influenced a little. What exactly are you seeing at the output of the INA196 in terms of voltage when the devices are outside of your specs? Be sure to tell me the current across the shunt under that condition as well.

  • Hello Nomer,

    We have not heard from you in a while. As such we presume your issue is resolved and will close this thread. However, If you need further support please reply below.
  • Hi Patrick,
    We tried shorting the shunt resistor and the output current measured fell within the 0-50mA spec around 20 mA which was previously above 50mA . whenever we lower the shunt resistor value the load draws higher current and the sink current decreases thus decreasing the output at pin 3. We shall be doing more sampling to finalize the shunt resistor value.

    I was able to get this part, see photos below, at the bottom marked 83Z2. which we got from our US facility which I mentioned to you earlier that this part is passed. Is this the same as 2008 batch? Is it discontinued?

    For those 2011 batches and onwards which originated from China facility we may consider to change totally to new shunt resistor.

    Thanks.