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TAS2559: TAS2559 Inrush current

Part Number: TAS2559

Hi Team,

We are using a TAS2559  Audio amplifier in our design.  During audio playing, codec shutdowns automatically due to peak inrush current need. We have measured up to 7.7A of peak inrush current at the input(VBAT).

Is this happens normally? 

We are operating the device in ROM Mode 1.  Is there any way we can control the peak inrush current?

We can replicate the same issue in TAS2559EVM also. Kindly suggest us the ways to reduce input current or some other relevant solution.

Also how to increase gain in ROM Mode using PPC3 Tool?

  • We have provided 4.2V, Upto 5A Current in VBAT. In our battery powered design we cannot provide more than 2.2A of current. So kindly help us in this case

  • Hi Manikandan,

    You may try to set BST_ILIM bits on BOOST_CTRL_2 register 0x2b to 00, this should limit boost current down to 1.5A, or you may also try with 2.0A configuration.

    If you still need to limit the output drive further down, you can use the Speaker Guard region of the voltage limiter. Default is 7.7Vpk but it can be reduced.

    Regarding gain control, you can refer to the attached document draft, it applies for ROM mode in TAS2559.

    Best regards,
    -Ivan Salazar
    Applications Engineer


  • Hi Ivan,

    In Tuning Mode, I have set 3.7V Inflection Point and class D peak voltage as 7.2V., but the amplifier reduces gain even if battery voltage is above 3.7V. 

    I have taken snapshot after applying 3.7V change in device control and Exported file from End system Integration tab.
    Do these changes apply in exported file? or suggest any ways that I could change the inflection point.

  • Hi Manikandan,

    Can you share a capture of your settings? Screen capture should be OK. Perhaps the speaker protection algorithm is attenuating the signal, you may check if this is the case by increasing Xmax and Tmax at Audio Procesing -> Smart Amp -> Characterization data. Do this carefully, you may want to use low input signals first to avoid damaging the speaker.

    Your settings from device control should be included in the end system integration files, however please make sure you first visit audio processing panel to load your changes on the tuning file.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • Hi Ivan,

    Thanks for the reply,

    I have tried Changing Xmax, but no use. Kindly suggests any other ways

    One more point,

    We have played audio at max volume and we can hear the audio output as the same,

    But when playing sine tone(0dBFS), the amplifier attenuates the signal. So we cannot calculate the maximum output power the amplifier is delivering.

    Is there any way we can measure/calculate maximum output power for the current setting?

  • Also, Is there any complete guide on tuning mode parameters?
    Is the smart amp mode mentioned in the datasheet is RAM Mode or Tuning mode?
    Is RAM Mode includes AGC, VBAT Tracking limiter, and peak class D voltage setting?

  • Hi Manikandan,

    • Can you try with the attached PPC3 file? I'm doing some changes on the Tuning and Audio Processing -> Smart Amp panel. This should bypass the protection (except for the anti-clipping)
    • If you need to test the device without any of the processing, you may configure it using the ROM Mode 1 or ROM Mode 2, these are available at Test and Measurement panel
    • Smart amp, RAM and Tuning mode are all the same, this is the mode which enables the internal processing features. ROM mode is the simplest way to configure the device, it works as a simple Class-D amplifier with digital input.

    Best regards,
    -Ivan Salazar
    Applications Engineer