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INA381: INA381

Part Number: INA381


I am using the IN381 as a overcurrent protection. 

As you can see, i am using PWM to control the intensity of the LEDs. Thus the question i would like to ask is that if at 100% PWM duty cycle, the INA381 detect a overload, but when i change the duty cycle to 50%, will the INA381 still detect overload at the high level of the PWM? 

If yes, are you able to advices how can i resolve this.. or should i change another detection method?

  • Hi Jimmy,

    it depends on what you want to detect. If it is the peak current you want to detect, then your scheme is right. But if you want to detect maximum average current, then you should eventually add some low pass filtering to filter out the PWM ripple.


  • Hi Jimmy,

    The circuit should work with slight modification. Like Kai mentioned, the amplifier output should be smoothed by a LPF before passed to the comparator. For this application, I assume it is desired to detect DC or low frequency over current events.

    The bandwidth of the LPF needs to be tuned so that it is slow enough to effectively average the output yet is fast enough not to miss over current events. You may use the attached TINA file as a starting point for this task.

    Regards, GuangINA381_LPF.TSC