TS3USBA225: U7 switch to Audio mode. Add 20-20KHz, 100mV sweep signal between pin8 and pin10, Pin6 and pin12 are highly distorted, up to 30%.

We tried 2 pcs defective products and replaced R2 R4 to 600 ohm. Distortion cannot be improved.

Clark,

What is voltage/state is SW_SEL1 during your testing? Can you confirm that the voltage seen at SEL1 is greater than 1.3 V? Can you confirm that the voltage seen at SEL2 is less than 0.4 V? What is VCC on your board when battery is connected?

Voltage at SEL1 is 3.45V, Voltage at SEL2 is less than 0.1V. When battey is connected the VCC on my board is nearly equal to battery voltage

AP test.When the IC is powered on with battety 3.7V.make SEL2 at low,change SEL1 from low to high. Add 1KHz,100mV signal to pin 8 and pin10,The THD+N at R and L is nealy 30%

Bad waveform:

Yellow one

 

 

 

Good waveform:

Purple one

 

Clark,

Is it possible for you to try with Vcc = 3.3V? Could you provide better image of wave form? I am unable to see any details.

Clark:
THD could be vary across supply voltage. We just want to see if high voltage cause the issue.

did you try 3.3v?

Please find attached schematic and answers below.
1
What is voltage/state is SW_SEL1 during your testing? Can you confirm that the voltage seen at SEL1 is greater than 1.3 V? Can you confirm that the voltage seen at SEL2 is less than 0.4 V? What is VCC on your board when battery is connected?
Voltage at SEL1 is 3.45V, Voltage at SEL2 is less than 0.1V. When battey is connected the VCC on my board is nearly equal to battery voltage
2
can you capture input and output waveform? how do you get 30% THD?
AP test.When the IC is powered on with battety 3.7V.make SEL2 at low,change SEL1 from low to high. Add 1KHz,100mV signal to pin 8 and pin10,The THD+N at R and L is nealy 30%

Hi Clark,

Were you able to test at Vcc = 3.3 V?