TAS5754M: the frequency response is not flat and begin to drop after 10KHz

Hi ,

We set PBTL mode and MONO output.The methods we tried to improve are as follows:

1. All band EQ settings are bypassed in PurePath Console 2.
2. We also try to reduce or increase the capacitance value in LC filiter.
But this problem has not improved.

Weichih Chen

Hi PY, Weichih,

Below is EVM captured data with 24V PVDD, -20dBFS optical input, 4ohm, PBTL channel frequency response. It doesn't have high frequency drops.

As for debug suggestions:

1. Change EVM PBTL output inductor and cap to your system components.

2. Check AP measurement filter setting and whether AUX0025 is used.

3. Route your system board I2S to EVM board PSIA. It is used to check whether it is caused by former processing.

4. As for output filter response, below simulation result shows 10uH+1uF 4ohm load should not have much high frequency drops.4.7uH might helps to implement higher cutoff frequency. But the current ripple current and idle power dissipation might goes higher.

Hi Matthew,

                    Thank you for your advice regarding high frequency improvement.

                     We use EVM and then captured data with 24V PVDD, 500mv aux input,PO 1watt, 4ohm, PBTL channel frequency response as bellow:

                     If set bypass status in all of bands,Why the low frequency(20Hz~200Hz) will drop 3dB ?

Weichih Chen

Hi Weichih,

What's your AP filter setting and frequency sweep setting?

One more suggestion to avoid former ADC influence, it's highly suggested to use PSIA input to remeasure it.

Regards,

Matthew