This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

INA301: High Frequency, Low Amplitude Current Monitoring

Part Number: INA301

Hello,

I am trying to design a current monitor for a sinusoidal signal operating at 480kHz. The behavior of the current monitor should be as follows:

If the current is >= 100mA (rms), then an LED will turn ON

Else, the LED will remain OFF

An error of 10mA is acceptable and a fast response time is not necessary

If a shunt resistor is used in the signal path to the input of the comparator in the INA301, and an LED at the ALERT output, and the appropriate Limit resistor is used for the 100mA threshold...will the INA301A1 work? 

Also, what would be the best way to estimate the power losses for the INA301A1 in this configuration?

  • Hello Canute,

    Thank you for considering to use Texas Instruments.  You should be able to have the INA301A1 alert trigger for a set current threshold.  You will want to operate in transparent mode, so that the alert signal returns to high after the current falls beneath the set trigger point.  The trigger point may end up being a little higher or lower than the ideal due to various sources of error.  If you need more information on those sources of error, I would recommend watching the following training video.

    As for estimating power losses, you can calculate the power of the device by multiplying the quiescent current by the supply voltage (Iq * Vs).  You can also get the power lost through the shunt by multiplying the squared load current through the shunt ( (IL^2) * Rshunt).  Lastly, I presume you will use the alert to switch a mosfet on or off for turning on the LED. There you would take your supply voltage and multiply it by the current you intend to run through the LED.

  • Patrick,

    Thank you for your reply and the link to the training video/series.

    My next steps are to watch the training videos, reread the datasheet and simulate the design in TINA.

    I have one follow up question for you, since the output is an open collector, couldn't I just connect an LED to the output (with a current limiting Resistor), rather than using a MOSFET? Or was MOSFET suggestion due to the 480kHz switching that would occur?

    Regards,

    Canute
  • Hello Canute,

    You raise a valid point. Looking back at what you originally asked for, the LED indicator would do the opposite of what you wanted according to my original suggestion. Sorry for misleading you on that. As you proposed, I think an LED between your supply and ALERT with a series current limiting resistor will do what you want.
    Let me know if you have any further questions.