we are making a few thousand boards based on amplifier chip TI 3116...

Hello,

1. Bulk PVCC capacitance between the SMPS and the amplifier is key for good audio quality to allow for audio transients. The more the better. Make sure to also bypass any large electrolytic will smaller high quality capacitors such as X7R ceramics or COGs. This will reduce the effective ESR and inductance of the capacitive filter. A series inductor will help with the ripple but it must be rated for the current and should be very low DCR. In most cases if enough capacitance is used, the PSRR of the amplifier will reduce the remaining ripple without an inductor.

2. A separate captive filter on the AVCC pin is also recommended before tying it to the main PVCC input. 0.1uF should be fine.

3. It is also recommended to add capacitance the input side of the SMPS similar to the filter used on PVCC. This will effectively buffer the SMPS from the source and the amplifier load.

4. Make sure the power and ground return traces are very large for low IR drop and keep the SMPS current loop as small as possible. Input filter and output filter capacitor grounds on the SMPS should be tied very close to each other with a very heavy ground bus.

Best Regards,
Matt

Matt,

Thank you for your reply.
We are checking on our side and will get back to you if anything.

All the best.

Andre

Hi again Matt,

here is another question on the subject:

We are looking on making our own power supply for the TPA3116.

Do you recommend a regulated power supply for the above IC ? Generally a class D amplifier benefits from regulated power supply (assuming that it has enough A) versus unregulated ?

thank you

Hi Andre,

Most regulated boost converters today should work will with Class-D assuming they can deliver the current at the target rail voltage and amplifier power. This will provide better efficiency over an LDO regulator or unregulated supplies. The high currents associated with Class-D amplifiers make switch mode power supplies the best choice.

For reference with low power Class D amplifiers (10W per channel into 4 ohms) the TPS61088 @12V does very well.

Best Regards,
Matt

Dear Matt,

Our question still stands…does TPA3116 specifically (and class D amplifiers generally ) benefit (audio fidelity point of view) from a regulated power supply versus unregulated ?

Thank you

Hi Andre,

Due to the reduced supply impedance and stiff voltage rail, a regulated supply will provide better audio fidelity and more headroom.

Regards,
Matt

Hi again Matt,
can you please share your thoughts on this:
We are thinking to design a resonant power supply (smps) for TPA3116 IC…
Is there an advantage to add active PFC to SMPS ?”

thank you as usual.

Matt,

On TPA3116 we are thinking to change the bootstrap capacitors from ceramics to polypropylene any advantage/disadvantage ?

Thanks again for your support, we are trying to release the best product on the 3116!

Regards

Hi Andre,
Since the bootstrap caps are level shifters to drive the high side FET gates, as long as they can hold charge for the switching cycle they work fine. Using better caps should have little to no impact on performance. Usually X5R ceramics or better are sufficient.

For best audio performance, I would however consider using a film caps for the output filter or for power supply decoupling in parallel with the electrolytics (.01uF range) due to their superior voltage coefficients, low ESR, and low inductance.

Regards,
Matt

Dear Matt,

What is the best schematic to add volume control to a TPA3116 using an analog pots ?

Also we have the option of using a digital pot with memory . However we need a 5V supply for it (coming from ARM CPU board) and we are afraid that dirty digital supply will affect the sounds quality

What do you think it’s the best decision ?

Thanks

Dear Matt, we will experience the same pop noise with a digital pots?
thank you
Andre

If the pots are resistive in nature then then thy could cause a pop on startup only. However you can add resistance to the negative input to help tune the RC charge time.

If you have a processor in the system where you can sequence Mute and SD then pop can be minimized. (aka pull SD high before pulling Mute low)

Matt