Slope compensation can be added in all current-mode control applications to cancel the peak-to-average current error. Slope compensation is necessary in applications with duty-cycles exceeding 50%, but also improves performance in those below 50%. Primary current is sensed using resistor RCS in series with the converter switch. The timing resistor can be broken up into two series resistors to bias up an NPN voltage-follower, as shown in Figure 32. This is required to provide ample compliance for slope compensation at the beginning of a switching cycle, especially with continuous-current converters. The voltage follower drives the slope compensating programming resistor (RSC) to provide a slope-compensating current into CF.