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TPA6100A2: current supply to the TPA6100A2 IC and on the TPA6100A2 EVM are quite large different WHY?

DaveLee75
Prodigy 205 points
Part Number: TPA6100A2
Other Parts Discussed in Thread: TPA6132A2

Hello TI support,

Question for the current supply to the TPA6100A2 IC and on the TPA6100A2 EVM are quite large different

I got the TPA6100A2 EVM to evaluate the TPA6100A2 and want to know why:

  1. TPA6100A2 data sheet said " Low Supply Current ...0.75 mA"

  2. EVM board listed (page 1-3)  160mA

from 0.75mA to 160mA is HUGE diff.

Why?

  • 0
    TI__Guru** 103695 points
    Hi David,

    The current mentioned in data sheet is the expected current consumption for the specified output power, which is at THD+N = 1%.
    The EVM is considering the maximum possible current that the device could demand in situations with large signals, plus some headroom to avoid damaging the power supply; in such cases the output signal would most likely be distorted and the current will raise.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0 in reply to Ivan Salazar
    Prodigy 205 points
    So, If I do want to have a very low Supply current audio OPAMP for my portable audio application, then please let me know others better than this TPA6100A2 IC?
  • 0 in reply to DaveLee75
    TI__Guru** 103695 points
    David,

    If this is a headphone application, I would recommend one of our TPA613x devices, like TPA6132A2. These devices have internal charge pump for GND centered signals and output coupling capacitors can be removed.
    0.75mA from TPA6100A2 spec is a quiescent current spec, the current consumption during playback would depend on the load and signal.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • 0
    Genius 3945 points
    " 1. TPA6100A2 data sheet said " Low Supply Current ...0.75 mA"

    That is the part's quiescent current; that is, the current required for the part to work without any input signal.

    The device is a power amplifier, so work out the AC (dynamic) supply current required with a given load and output power. From the data sheet, output power at 3.3 V supply into a 16-ohm load is 50 mW (at a given distortion spec). Ohm's Law tells you the current required for that is ~60 mA.

    And that is per channel! So you must double the current draw for two-channel operation, or 120 mA. This is what you might measure when you feed both inputs with a hot signal.

    " 2. EVM board listed (page 1-3) 160mA"

    That is consistent with the 120 mA I derive above. Note that my value is base on a particular load impedance, power output and distortion spec. If you allow for higher distortion the output current will be higher. The worst case of 160 mA is probably derived at by completely clipping the input into a tough load, and letting the chip's internal power-dissipation limiting do its thing.

    So if you are designing with this part, or indeed any amplifier device, you have to pay attention to not only the quiescent current draw spec but also the dynamic draw -- and that dynamic draw will _always_ be higher than the quiescent.