FS6500 VAUX incorrect

[TianYiShen]

I have set 5.1K resistor to select PIN, and VCCA is correct(3.3V).Though, VAUX is 4.8V. Does that mean that my  chip is broken?

[TianYiShen]

Due to security consideration, I am not allowed to tell you exactly what we have applied in the circuit, but there are capacitance and resistor, and I simply just blow these loads down & put them on again, the output will be correcrt. Though, 4.8V will come back in hours or a few days. I haven't found any other efficient solutions yet. Wishing to have your suggestions. Best regards.

[TomasVaverka]

Hi,

If you are not allowed to share the schematic or at least part of it with Vaux, it will be difficult for me to analyze the issue further. Could you please at least confirm that you are using correctly the PNP transistor as illustrated in the datasheet or AN5238?

Again, without knowing more details about your implementation and seeing your schematic, scope plots of Vaux_E and Vaux_B etc. I cannot really provide more suggestions.

BRs, Tomas 

[TomasVaverka]

Hi, 

With Rselect = 5.1 kOhms, both Vcca and Vaux should be 3.3V.

In order to analyze why Vaux is 4.8V in your case, please share your schematic or at least part of it with Vaux and the PNP transistor.

Could you please also provide scope plots of Vaux_E and Vaux_B? What is the load connected to Vaux?

Does your PNP transistor meet the requirements shown in our AN5238?

Best regards,

Tomas