Dear All,
I'm using a DCDC regulator to provide a power supply to a class D amplifier. The output DCDC voltage is trimmed by a INA190 curren sensor. It means that if the amplifier needs mor current the INA output will increase and the DCDC voltage will decrease.
The class D amplifier is amplifying a 5MHz clock frequency.
If the 5MHz oscillator is off, the INA's output voltage is a constant DC level as expected.
If the 5MHz oscillator is running, the INA's output voltage is producing an oscillation superposed to the DC voltage around 300/430kHz.
I have tried to filter the INA inputs with a LPF at 10kHz without success.
I can supress this oscillation with a LPF in the INA's output but, due to the oscillation, the output voltage cannot go below 0.8V.
I saw in the datasheet ithat INA is zero drift amplifier that is certainly using a chopper architecture. I suspect the mixer inside the INA to fold RF frequency.
Could you please confirm if my expectation is right?
Could you please propose a way to make the INA immune to RF freq?
Thank you for your help.
Best regards,
Arnaud