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LME49830 PCB/schematic mismatch.

Johan Lavent
Prodigy 10 points

Hi,

I noticed a mismatch between the schematic and the PCB of TI's LME49830 reference design. Mismatch is in the BIAS circuit.

In the schematic the two caps are connected after the RB3 resistor but in the PCB they are connected before the RB3 resistor directly between the BIASP and BIASM pins. I don't think that it is very critical but which connection is the best for these caps?

Br,
Johan.

  • 0
    TI__Expert 8190 points

    Johan,

    You are right that it does not make a lot of difference.

    I personally would prefer to connect the caps after RB3 to also limit the inrush current through CB2.

    Question:

    Is there a specific reason to choose the LME49830 that is designed to drive MOSFETs?

    I have seen that audio MOSFETs are getting more difficult to get, are more prone to oscillations and their power handling capabilities are roughly half of that of BJT's.

    I have built a poweramp using the LME49810 and Sanken BJT's.

    Advantage is that power rating per transistor is 2x that of MOSFETs, output swing is higher due to the much lower

    Vce min versus Vds of the FETs and they are cheaper.

    I also added a servo loop to avoid the large input caps for DC output correction.

    Have a look at my website www.transientelectronics.nl under DiCOSS -> AMP