The datasheet for the UCC28C43 says when describing the current sense pin says "A voltage ramp can be applied to this pin to run the device with a voltage mode control configuration." What does that exactly mean?
Hello Andy,
The mode of the controller is decided through a comparator that compares the control threshold to the ramp of the CS voltage. This controller is normally functioning in current sense mode but generating a 0-V to 0.9-V sawtooth-shaped signal as an input to the current sense pin (CS) provides an additional ramp to the CS signal. This feeds into the comparator, and then through the error amp. The error amp output is varied, it intersects the sawtooth waveform at different points in time, thereby generating different pulse widths, thereby generating the pulse whose width is proportional to the error voltage.
Even with the current mode the slope compensation is required to stabilize the overall loop with duty cycles exceeding 50%. This is achieved by the following addition to your design in case of UCC28C43:
Please refer to the datasheet for further information regarding its design.
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Thanks,
Sonal
