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INA296B: INA296B1

Anton Bityaev
Prodigy 20 points
Part Number: INA296B

Hello,

In our application INA296B1 is used to sense the current in different scenarios where the voltage is sensed on a low-side shunt, however that battery (having shunt on the low side) is switched and connected in series to another  high voltage bias (up to 70v), so INA296 is very good IC for that, since it is able to sense bidirectional current in all range of CM voltage. In one time slot it senses the current close to ground (Low side) in other time slot the system switches and connects that part to high voltage bias and then the INA296 senses the current with CM voltage of 70v.

My issue comes up in reverse negative transient voltage (due to power FET switching, which disconnects the power loop). At that moment I'm getting up to -60v for ~50msec of negative voltage on the shunt and it damages the amplifier instantly. My questions are as follows:

1. Is it possible to add serial resistors between the shunt and INA296 inputs so I can add protecting TVS diodes which will clamp the negative voltage on INA296 inputs

2. Is there any other suggestion for protecting the INA296 from reverse voltage (again it goes down towards -60v). PMOSFETs? (considering that the current is measured in low side and  variety of CM voltages depending on system process.

Thanks

Anton

  • 0
    Guru 140200 points

    Hi Anton,

    can you please give us a schematic or at least a scheme which shows how the batteries are connected and switched?

    Kai

  • 0
    TI__Intellectual 1235 points

    Hi Anton,

    Anton Bityaev said:
    1. Is it possible to add serial resistors between the shunt and INA296 inputs so I can add protecting TVS diodes which will clamp the negative voltage on INA296 inputs

    This is possible, however these additional resistors will result in greater error due to the bias current going into the input pins. We have a reference design that describes this solution linked here, however, this solution was created for transients much shorter than what you are experiencing at 50mS.

    Anton Bityaev said:
    2. Is there any other suggestion for protecting the INA296 from reverse voltage (again it goes down towards -60v). PMOSFETs? (considering that the current is measured in low side and  variety of CM voltages depending on system process.

    There may be better solutions for your design than adding a TVS diode as you mentioned. Can you provide a schematic so we can investigate other solutions?

    Thanks,

    Cierra