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Frequency rating of TAS5162

Patroklos Anagnostou
Prodigy 50 points
Other Parts Discussed in Thread: TAS5162

As TAS5162 and similar amplifiers are meant for audio applications, the upper operating switching rate is specified to be 432kHz in the datasheet.

We are trying to use the above chip to amplify a PWM signal of 1.2Mhz and I see that the output is quite satisfying. The target energy to be delivered will be under 5-10Watts and the PVDD supply only 20V (the IC is rated for 2x210Watts and 50V).

So we would like to ask if have you tested the amp for higher frequencies. Is heating the only reason of the 432kHz limit or is there some other failure/degradation mechanism to be expected?

Thank you for your support

  • 0
    TI__Genius 9175 points

    Hello,

    At the full PVDD supply voltage used for our high power devices, switching losses would be quite high and thermal performance would be bad when switching in the MHz range. Even at lower a PVDD supply voltage, the switching losses are high since the output FET size is large on these high power devices. This means that the gate capacitances are also larger.

    The other performance limit is charging of the bootstrap (BST) caps. For the BST cap size, there is a minimum PWM low timing specification to insure that the capacitors are fully charged.

    What is your end application?

    Best Regards,

    Matt

  • 0 in reply to Matthew Beardsworth
    Prodigy 50 points
    Hello Matt,

    We are looking for an energy efficient amplifier (hence class-D) to act as a voltage source, delivering signals of 20V amplitude up to 5-10Watts.
    If the thermal losses are the only issue, a 420W IC should deliver the 5W without degradation in lifetime, as long as it does not heat up, isn't that so?
    Do you contact any tests around 1Mhz? Is there any alternative (preferably pin-compatible) you would suggest?

    Best regards,
    Patroklos
  • 0 in reply to Patroklos Anagnostou
    TI__Genius 9175 points
    Hello Patroklos,

    We have not tested this amplifier at higher switching frequencies other than specified in the datasheet as this was the design target. Therefore >1MHz switching is unknown. For faster switching frequencies the audio performance is no longer guaranteed to meet the datasheet and the device will mostly likely have reduced performance. This is assuming the device is able to function at all.

    This will require testing for your specific application to see if will meet your design goals.

    As long as you are able to adequately heat sink the device to keep it cool, I don't foresee any issues from a thermal perspective.

    Let us know your test results!
    Best Regards,
    Matt