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INA302-Q1: Queries in datasheet

Sri Viswa Sathiamoorthy
Intellectual 290 points
Part Number: INA302-Q1

Hi,

We are using INA302A3QPWRQ1 in the design. Please provide response for the below queries

1)How the offset voltage varies with temperature? Whether offset voltage increases with temperature or vice versa? The value provided is positive (0.25uV/C), so can it be considered that offset voltage increases with increase in temperature?

2)How the gain error varies with temperature? Whether gain error increases with temperature or vice versa? The value provided is positive (10ppm/C), so can it be considered that gain error increases with increase in temperature?

3)How to include non-linearity error in the calculation? Whether it can be added with gain error?

4)In the datasheet pgno:6, internal programmable delay error is provided. Where this "internal programmable delay error" term will have an effect? Whether it will affect the delay time set by external capacitor? If so, what is the formula to calculate the same?

5)Whether Vout pin can be left floating?

6)In the datasheet pg no:5, recommended differential voltage is provided as 25mV. In our design, differential input voltage is coming around 27mV. Whether this recommendation can be violated?

Thanks

Viswa

  • 0
    TI__Mastermind 27590 points

    Hi Viswa,

    1)      The positive drift number doesn’t necessarily mean that offset voltage increases with temperature. As can be seen from this typical curve, Vos is actually trending down. It only starts to peak up after 125⁰C:

    2)      Similar to Vos. Here is the typical curve for gain error:

    3)      Yes you can add it to gain error. Here is a video on the topic of error calculation if you’re interested.

    4)      The delay formula is give below. The delay error can be used to account for uncertainties due to device internal properties. The delay capacitor’s tolerance will need to be accounted for separately.

    5)      Yes Vout can be left floating

    6)      The 25mV differential input is the maximum determined by the specific configuration. It comes as a result of output swing limitations. Theoretically the device output will be clipped after 25mV. But other than that, 27mV won’t cause damage.

    Regards, Guang

  • 0 in reply to Guang Zhou
    Intellectual 290 points

    Hi Guang,

    Thanks

    Queries in 4th and 6th point

    1)In 4th point: VTH and ID has minimum, typical and maximum variation provided in the datasheet. Whether the 4% indicates these error or it has to be included separately like

    Delay=((C*VTH)/ID + 2.5us)*(1+4%)

    2)5th point:

    In our case Vref=0V and Vs=4.9V. Hence output for 27mV will be 2.7V, which is within 4.8V (Vs-0.1V). Hence in our case, it also won't cause that issue. Is it right?

    Thanks

    Viswa

  • 0 in reply to Sri Viswa Sathiamoorthy
    TI__Mastermind 27590 points

    Hi Viswa,

    1)      In 4th point: VTH and ID typical should be used and these errors don’t have to be included separately. Delay=((C*VTH)/ID + 2.5us)*(1±4%)

    2)      5th point, your understanding is accurate.

    Regards, Guang