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TAS5727 Over-Current Limit

Alex Fink
Prodigy 70 points
Other Parts Discussed in Thread: TAS5727

Hi,


Using the TAS5727 in a product, we are seeing current limit occurring at about 3A, whereas the amplifier spec says over-current limit protection is 4.5A nominal. Do you have any insight about this discrepancy?

Thanks.

Our power supply voltage is 19V. Our load impedance is 5.3 ohms.

I am attaching a trace of what happens below. The yellow and purple traces are the amplifier outputs, before the output filters. The green trace is the A_SEL/FLT pin, which goes low when the over-current event occurs.

  • 0
    TI__Guru 57800 points

    HI, Alex,

    This behavior seems related to a false over current protection event. You need to set up Modulation Limit Register (0x10) to the minimum (0x07) when operating with PVDD voltager larger than 18V. This must be done to ensure enough time is given to get the bootstrap capacitor fully charged, because these caps are charged during the minimum PWM cycle. If the caps are not fully charged, then the power stage won't be fully turned ON, causing a false over current event.  

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 70 points
    This appears to have fixed our problem. Thank you very much.