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LM4952: Power supply current estimation

Kazuki Itoh
Genius 10085 points
Part Number: LM4952

Hi team,

Could you please let me know how to estimate power supply current when RL=8Ohm (4W) speaker and VIN=12V?

The datasheet shows that for RL=4Ohm in Figure 35. But I cannot find what I want (RL=8Ohm).

Regards,

Itoh

  • +1
    TI__Guru** 103725 points

    Hi Itoh,

    You may consider this power supply current values as worst case, considering that current will be lower for higher impedance loads.
    Unfortunately there is no model or EVM to test different configurations.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    TI__Genius 10085 points

    Hi Ivan-san,

    My customer actually means the supply current with input.

    VDD：12V
    Vin：1kHz(0.58Vp-p)
    Vout：5.8Vp-p/8Ω
    DC-VOL：3.3V
    SD：3.3V

    My customer's measurement result is 97mA.

    How can I estimate the worst case?

    I calculated from Eq.(1) on the datasheet, but the result was 75mA (=12 / (2*pi^2*8)), which is smaller than the measurement result.

    Regards,

    Itoh

  • 0 in reply to Kazuki Itoh
    TI__Guru** 103725 points

    Hi Itoh,

    Using equation 1 you consider the dissipated power, but still the power on the load is missing. Unfortunately there is no efficiency number either to add in the calculation.

    Best regards,
    -Ivan Salazar
    Applications Engineer