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TPA6120A2: Maximum driving level

Jagdish Patange
Prodigy 250 points
Part Number: TPA6120A2

We are planning to use TPA6120A2 device as audio driver to drive headphone with load impedance of 600 ohm to drive upto 500 mW.

To evaluate the device I have used 20 pin SOIC device and connected the resistors by referring datasheet.

Rs=10 ohm, Rf=1.5k, Rb=1.5k, Ro=36 ohm on both left and right channels. Left  and Right inputs are configured as single ended.

Balanced Input is given as single ended w.r.t. ground to left and right channel. 

Expected output is balanced output (Left output and Right output are in 180 degree phase shift).

This balanced output is expected to drive 600 ohm load for upto 500 mW.

When weI have tested we found that distortion has increased to 13.29% for balanced output level of 12.6V across 600 ohm.

we request you provide maximum driving capabilty (voltage level) across 600 ohm load for +/- 15V supply.

Or suggest any equivalent driver.

 

Regards

Jagdish and Pavan

  • 0
    TI__Genius 14011 points

    Jagdish & Pavan,

    I will look into this amplifier for you; please take a look at this existing thread for some insight on output voltage swing range and effect of load impedance:

    https://e2e.ti.com/support/audio-group/audio/f/audio-forum/722204/tpa6120a2-tpa6120a2-power

    Best,

    Alec

  • 0 in reply to Alec Saebeler
    TI__Genius 14011 points

    Hello Jagdish & Pavan,

    The TPA6120A2 is able to drive a high impedance headphone due to its wide input range (12.5 V to -12.2 V on +/-15V supplies) and output current abilities (700mA).  Are there any other metrics or figures of merit for your design you are focusing on?  Is the 500mW output the peak output power?  Do you have target for average power?

    A direct answer to your question would be 12.5V, according to the datasheet.  The headroom needed between the +15V supply rail and the max output swing of 12.5V is due to the current feedback architecture of the IC.  This architecture allows gain to be mostly independent of bandwidth, for properly selected feedback resistor values.  Current feedback architecture also enables a much higher slew rate than most voltage feedback op-amps.

    Please also see the curves present in the datasheet for distortion performance at various loads and gain configurations.  In general, driving a high impedance load will require a higher voltage (and overall power) than a low impedance load, but the distortion performance will be better.

    Best,

    Alec