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INA197 Max Power

David Merrill
Intellectual 2305 points
Other Parts Discussed in Thread: INA197

What is the maximum power consumption of the INA197AIDBVT?

Thanks.

  • 0
    Guru 21975 points

    David,

    I assume that this is a customer question. It may help to know the purpose of the question as the best answer may depend on the reason.

    The quiescent current is 900uA or 950uA max over temperature. In round numbers let's call it 1mA. The power supply can be from 2.8V to 18V. So if they are operating at 2.8V, the max dissipation is about 2.8mW. At 18V it's about 18mW.

    This assumes that the load current is small. Output current comes from the power supply pin and, depending on the nature of their question, may be considered part of the power consumption. Figure 8 also shows that quiescent current is somewhat dependent on output voltage so this introduces another variable.

    Again, if we can get an idea of their concern, I'm sure we can narrow in on an answer.

    Regards, Bruce.

  • 0
    TI__Guru 60610 points

    David,

    The absolute maximum power dissipation of the INA197 occurs when the output voltage is at the negative rail and it delivers 32mA short-circuit current at -40C (see graph below).  Under such conditions, the total power dissipation is 576mW (18V*32mA) resulting in 115C rise of chip temperature (0.576W*200C/W=115C).

    .

  • 0 in reply to Marek Lis
    Guru 21975 points

    David, Marek,

    The original question asked for "power consumption," which suggests that the customer may be interested in the power requirements under more normal operating conditions. Marek could well be correct, that they want to know the absolute dissipation under extreme conditions... don't know. That's why you may want to ask how they intend to use the number. It would not be correct to assume, for example, that the power supply for the INA197 must be capable of supplying 0.57 watts because its power consumption could be this high.

    Anyway, the number that Marek correctly calculates will not occur unless they are operating at the 18V maximum operating voltage. Furthermore, during output short circuit, it would not occur for long as the chip temperature would rise very quickly, reducing the output current.

    Bruce

  • 0 in reply to Bruce Trump
    TI__Intellectual 2305 points

    The customer is trying to perform a reliability analysis for the device is looking for the tolerance on the Power Consumption.

  • 0 in reply to David Merrill
    Guru 21975 points

    David,

    For purposes of reliability calculations I recommend that the dissipation be calculated at nominal operating conditions. To estimate the dissipation we need to know the supply voltage applied to the V+ terminal, pin 5. Also we should know the load on the output terminal, pin 1.

    I'm confident that with this information, the power dissipation and temperature rise will be very modest, much lower than the extreme, non functional conditions that Marek calculated.

    Regards, Bruce.