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Suitable Current Sensing IC ??

Nikos Chatzis
Prodigy 120 points

Other Parts Discussed in Thread: INA181

Hello,

Our RnD department is in the designing process of a traffic lights controller. The output stage of this device is being designed to drive various loads (Incandescent lamp or LED power supply, both operating on 230VAC) thus the nominal output current is 320mA and 60mA respectively. So, we want to design a circuit to measure this output current so as to determine the susceptibility of the device. We desire the measurement’s step resolution to be 5mA.During the research process we found that there are many different ways to measure current (indirect sensing using Hall Effect sensor or direct sensing using current transformer, operational amplifier, differential amplifier, instrumentation amplifier and current sense amplifier) but we ended up to use the shunt resistor method. The basic measurement circuit is shown on the attached image.

We would like you to recommend some of your available ICs to help us build an efficient and low cost design.

Thank you in advance

Best regards,

Nick

  • 0
    TI__Expert 4915 points

    Hi Nick,

    I would recommend the INA181 as a viable solution for your application.

    You need a separate power supply referenced to the in+ Input and the ref input biased to 1/2 of the uC voltage so as to be able to measure AC currents.

    For simplicity, I recommend placing RShunt before the switching device, that way a simple buck non isolated power supply can be used, with the reference being the live wire. This is to keep the common mode voltages within the limits of our device.

    The Error would be more or less as given by the tool on this page, so well within your requirements.