Adaptive Pull-Up Resistance for SMPS Start-Up Overshoot

The pull-up resistance is changed from a fixed value to a dynamically adjustable value that varies with operating conditions. The controller selectively sets different resistance values based on whether the power supply is in start-up mode or steady-state mode, allowing the circuit to adapt to different operating conditions and prevent overshoot during start-up while maintaining simplicity in steady-state operation.

The oscillation frequency is changed from a fixed high value to a time-varying frequency that follows a periodic pattern during start-up. The controller uses a sawtooth wave signal to periodically adjust the oscillation frequency, creating a ramp-up effect that gradually increases frequency over time. This periodic modulation prevents abrupt frequency changes that cause overshoot while still achieving fast response once the frequency stabilizes.

The complex compensation RC networks are extracted and removed from the circuit. Instead of using traditional analog compensation components, the invention implements overshoot prevention through digital control mechanisms - specifically by dynamically adjusting the pull-up resistance and oscillation frequency through firmware logic. This extraction eliminates the need for complex analog fine-tuning while maintaining output voltage stability.

The controller performs self-service by automatically detecting its own operating state (start-up vs. steady-state) and autonomously adjusting the pull-up resistance accordingly. The system uses internal state machine logic to determine when to switch between resistance values without requiring external intervention or complex additional control circuits. This self-service approach maintains simplicity while achieving adaptive overshoot prevention.