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INA253: A1

Kirill Kostyushkin
Prodigy 30 points
Part Number: INA253
Other Parts Discussed in Thread: TPA3144D2,

Dear colleagues,

We use INA253A1 (gain 100mV/A) and the same schematic as on Figure 43 (in datasheet). Vs=Vref=3.3V.

The measuring signal is  from amplifier out TPA3144D2. The incoming signal to amplifier is sinus tone 1kHz, load is 8 Ohm.

On the Vout of INA253 we see sinus 1kHz with amplitude 1.2-2.4V. Could you please help to interpretate this value in to current value?

  • 0
    Guru 140200 points

    Hi Kirill,

    have you read section 9.2.2 of datasheet of INA253? There you will find an example calculation.

    Kai

  • 0 in reply to kai klaas69
    Prodigy 30 points

    Kai hi,

    Yes, we read the 9.2.2.  If we put gain 100mv/A in formula we get Irms 6-10A. Sorry, where we have error?

  • 0 in reply to Kirill Kostyushkin
    TI__Mastermind 27715 points

    Hello Kirill,

    Can you please confirm the DC current level of your 1kHz sinusoid and the connections at the pins REF1 and REF2? In your original post you state that Vs = Vref = 3.3V. In this case the INA253 output is referenced to the power supply and would only change when input current < 0 A. Are you intending to set the reference to mid-supply instead? In that case you should connect REF2 = Vs and REF1 = GND.

    Please see section 8.4.4 of the datasheet for more information.

    Below is an example calculation if you set Vref = Vs/2 = 1.65V. You need to back-calculate input current by dividing (Vout-Vref) by Gain.

    Spec Value Unit
    Vout_max 2.4 V
    Vout_min 1.2 V
    Vref 1.65 V
    Gain 0.1 V/A
    Vout_max - Vref 0.75 V
    Vout_min - Vref -0.45 V
    Iload_max 7.5 A
    Iload_min -4.5 A

    Best regards,

    Ian Williams
    Applications Manager
    Current Sensing

  • 0 in reply to Ian Williams
    Prodigy 30 points

    Ian hi,

    Thank you very much for explanation. It's clear. Also I add that on our schematic Vref1=GND, Vref2=Vs. You were right.