After choosing the current sense resistor, transformer inductance and transformer turns ratio, verify the required slope compensation against the fixed internal slope compensation. The worst case slope compensation requirement always occurs at the highest duty cycle operating point (at minimum bulk voltage level).
For stability, the slope compensation should be at least 50% of the difference between the inductor up-slope and down-slope. [reference Bob Mammano TI Power Supply Design Seminar paper, 2001, SLUP173]. For a flyback converter, the difference in slopes in CCM is equal the operating duty cycle multiplied by the inductor current down-slope value. For example, for 50% dBULK(min) at minimum bulk capacitor voltage, the required slope compensation ramp is 25% of the inductor current down-slope.
As listed in Table 7, the specified peak-load transient is 130 W for 2 ms. In a worst case, peak transient timing with respect to the AC phase, the VBULK minimum level dips to 65 V. This corresponds to a duty cycle of approximately 63.5% according to Equation 50.
The required slope compensation ramp is calculated at 63.5% duty cycle.
This value is within the 30 mV/μs of internal slope compensation provided by the controller.