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UC3846: Duty regulation and current protection threshold on UC3846

Part Number: UC3846

Tool/software:

Hi,

Measuring the parameters you mentioned, I have another question. In the following image, the signals you mentioned in the previous message are shown. In this image, the control is working correctly and we have the desired voltage at the output.

However, analyzing this waveform, I have noticed something. The peak voltage of V_C/S+ is approximately 200mV, and since the chip has an internal gain of three (as shown in the next image), the voltage at the comparator is 600mV. The current protection (V_C/S_SS) is set to 1.25V, and the voltage at the COMP pin is 1.7V.

With these limits, why is it regulated well at 100V? Shouldn't the current protection activate earlier?

Thank you for your assistance.

Best regards,

Mikel

  • From the data sheet, you can program the current sense threshold according to below. Use this as your method for determining when the current sense is entering an overcurrent mode of operation.

    Steve