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Original question:

Chaos while choosing the amplifier(current sense)

INA226: Selection request

Minqi Zhao
Intellectual 1660 points
Part Number: INA226
Other Parts Discussed in Thread: INA229

Dear expert,

My customer is looking for a solution in LED controller to sample the voltage, current and power. Here are the spec they need:

  • Supply power is 3.3V
  • Voltage measurement is 24VAC(50Hz) and 12V/24V/48VDC
  • Current measurement is 10A
  • Low side sensing
  • Sampling error<1%
  • Temperature range is -30~70C
  • Load is ADC

They are fine with sampling voltage&current then calculate the power. However they prefer to IC that can directly sample the power of AC. Please share your solutions and related materials, thanks!

  • 0
    TI__Mastermind 26335 points

    Hello Minqi,

    Thanks for reaching out on the forum.  With a 50 Hz signal, each period is 20ms.  To reconstruct a 50Hz sinusoid would likely require a sample conversion duration 1/5 or 1/10th of that or <2ms.  As both INA226 and INA229  have internal ADCs with conversion times less than that, I think they would be applicable to your customer.  However, only the INA229 could be used for directly monitoring the 48VDC bus.  You could use a voltage divider and do some post processing.  However, that will introduce more error into your measurement.  For calculating error, you can use the excel document I am attaching, which has error calculations for INA226 on one sheet and error calculations for the INA229 on another.

    /cfs-file/__key/communityserver-discussions-components-files/14/PowerMonitorCalculator.xlsx