I redid the calculations and 68µH should leave enough margin to stay in DCM. Verified experimentally -- things work just fine with both 47µH and 68µH inductors. No unstable behavior anywhere in DCM, though I still have to build a circuit to test the transient response.
[quote user="Anthony Fagnani"]
Your understanding in b looks correct. The slope compensation is fixed and you have no influence. This equation is mostly to ensure the slope compensation is sufficient for the sense resistor selected in your design. It is discussed to help give some understanding of why this limitation is placed on the sense resistor. The slope of the actual internal ramp is given by Equation 8.
[/quote]
Ok. So my sense resistor is 50mΩ. The maximum calculated value to avoid instability is 3mΩ. Two questions:
1. Am I right in thinking that by using the maximum acceptable value I basically give up overcurrent protection, and there is nothing that can be done about it?
2. Instead of using a smaller Rsense, can I add a resistor across C12, thus forming a divider which would scale Vsense down?