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INA139-Q1: tolerance of RG1

Part Number: INA139-Q1
Other Parts Discussed in Thread: INA139

Hi sir,

I have some queries on this device need your verification.

1.is there a problem if I input an analog input signal before the power turning on?

2.How much is the resistance tolerance value of the internal resistance (RG1)?

  What is the percentage temperature deviation due to RG1 value deviation?

Thanks.

Regards,

  • Hello Frank,

    Thanks for reaching out on the forum.

    1.  The device should not be damaged if there is an input signal before the device power is turned on.

    2.  I will need to check with our designers, but usually internal resistances connected to the inputs are within 15% of the diagram stated value, while the tolerance between both input sides is very small due trimming.  Why do you need to know this?

    I will also check with our design team about the temperature, but the most I may be able to divulge is the specs for transconductance versus temperature and offset versus temperature.

  • Hi Patrick,

    Thank you for your response.

    These queries are from our customer, I will confirm the background why he wanted to get this resistance  tolerance info with him.

    Thanks.

  • Hello Frank,

    I got feedback from one of our designers.  15% does not apply to this architecture.  Resistance tolerance can be determined from the transconductance specification which is +/-1% worst case.  As for temperature deviation due to RG1, +/-10ppm/C typical and +/-25ppm/C max.

  • Hi Patrick,

    Thank you.

    Customer is going to make current detection circuit using INA139,
    so he asked the question because the internal resistance deviation is important parameter in order to calculate the accuracy of the current detection.
    For Q1, would it be possible to input the analog signal to the INA139-Q1 frequently (in a few days level) before power turning on?
    in other words, durability in this case.

    Also, the voltage of VSENSE becomes about 13.5 V,
    but what is the dark current that flows before the power supply in the state where 13.5V is applied?
    Because it is the information necessary for calculation of battery

    Thank you.

  • Hello Frank,

    So I talked with a design engineer, and he said as long as it is within the recommended operating conditions, there is not a problem.  But as you know, Vs would be below the recommended condition which puts the operation somewhere between the recommended and absolute max conditions, which pertains to the note below the abs max table about reliability. According to our design engineer we do not have any reliability stats for such a condition.  To determine the reliability, would require investigation on the bench.

    If you have the condition (VIN+)-(VIN-)=13.5V that violates the abs max differential specification of 2V.  For VCM=13.5V when the device was not powered, the current was lower than my multimeter resolution (<1uA).