TEA2017 RSNSCAPhigh Function

[cduignanvox]

Hello,

My question is: is RSNSCAPhigh necessary for proper function of the TEA2017 controller?

Figure 49 from AN13140 shows that the DC voltage on the SNSCAP pin is regulated by a current source, which is why RSNSCAPlow must be greater than 15kΩ. This method of regulation shouldn't require RSNSCAPhigh, is it needed for some other function?

cduignanvox_0-1695814805904.png

Thanks,

Connor

[ErikaC]

Hello,

Yes, the RSNSCAPhigh is necessary for proper function of the TEA2017 controller.

The resistive part of the divider provides constant losses during operation and burst mode operation. To limit power losses, the total impedance must be high. For example, RSNSCAPlow + RSNSCAPhigh = 5 MΩ.

Hope this helps.

[cduignanvox]

Hi Erika,

Thanks for your reply.

I still don't understand why the resistor is necessary. If the resistor is removed, the power loss becomes zero, and SNSCAP still receives the waveform of the resonant capacitor through CSNSCAPhigh and CSNSCAPlow. The DC offset is provided by the bias current from the SNSCAP pin through RSNSCAPlow.

If I remove RSNSCAPhigh will it affect the performance of the controller?

Thanks,

Connor