Transient response enhancement method for DC-DC converters based on adaptive duty cycle adjustment

Abstract

This article presents an adaptive duty cycle adjustment DC-DC converter for improving load transient response. The combination of adaptive clock control and DAC output variable reference voltage allows for rapid duty cycle saturation to further increase the inductor current conversion rate, thereby accelerating transient response. Furthermore, a fast transient detection method based on duty cycle sensing is proposed for many problems such as the inherent delay generated by traditional load transient detection, which is highly accurate, fast, and less affected by PVT. And the second overshoot generated by the nonlinear transient enhancement is corrected to compensate for the instability in the recovery process of transient response Based on the 0.18 μm high-voltage BCD process, the proposed method is verified by specific circuit design and physical implementation. The test results show that the transient enhancement method proposed in this article reduces the overshoot/undershoot voltage of load transient response to 20 mV/27 mV under the design environment of clock frequency 0.75 MHz ∼ 3 MHz and load current fast stepping from −20 mA to −620 mA. Compared to the conventional PWM peak-current mode operation, the overshoot/undershoot voltage is reduced by 64 %/63 % and the overshoot/undershoot recovery time is reduced by 89 %/62 %.