Hi ,
We are using TAS5411QPWP Audio amplifier in one of our design. we have completed the schematic design for it .
We reviewed it at our end but looking forward for TI to review it. attaching the snip of Audio section of our design.our speaker are of 2.5W , for that reason we have changed Amplifier output Inductors and capacitor
as from the EVM from TI.
Please review it and share your inputs if i have missed anything.
Hi Deepak,
your power supply decoupling is a bit overkill. :-) Paralleling unequal ceramic caps with very low ESR can create nasty resonances. Have a look at the following TINA-TI simulations. First I simulate the impedance versus frequency response. Then I also take into account the ferrite bead and do a damping versus frequency simulation.
Datasheet of PCM1789 recommends a 10µ tantal paralleld by a 1µ ceramic. This is a nice combination, because the ESR of tantal will dampen the resonance:
But if you parallel 10µ ceramic, 1µ ceramic and 33p ceramic the following can happen:
When using a ferrite bead it's often overlooked that they usually have a considerable low frequency inductance combined with a very low ESR at low frequencies. This can additionally result in a resonance. With the tantal the resonance isn't high because it is damped by the ESR of tantal:
But when only having paralleled ceramics this can happen:
The performance when using the tantal can even be optimized by adding a small series resistane to the ferrite bead:
So, when it comes to power supply decoupling, "less can be more".
Kai
