Dual Constant Time Switching Regulator for Load Transient Response
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Solution Overview
Problem
Existing constant time switching regulators face limitations in load transient response due to fixed ON time, leading to voltage drops and unstable output performance, especially when the input voltage is close to the output voltage, resulting in high switching frequency and ripple.
Innovation Solution
A dual constant time switching regulator with an adaptive ON time extension capability, allowing the duty cycle to reach up to 100% without additional pins, achieved through a comparison circuit and time determining circuit that controls power switches based on output voltage-related signals, enabling seamless operation across a wider input voltage range with reduced ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the ON time is constant, then the control is simple, but the load transient response is poor and voltage drop occurs
Solution Approach 1:
The patent implements dynamic ON time adjustment by introducing a dual constant time control mechanism that extends the ON time based on duty cycle thresholds. When the duty cycle exceeds a first threshold, the ON time is extended by a first constant time; when it exceeds a second threshold, the ON time is extended by a second constant time. This dynamic adjustment allows the regulator to adapt to load transient conditions while maintaining manageable control circuit complexity.
Solution Approach 2:
The patent changes the ON time parameter dynamically based on duty cycle conditions. By monitoring the duty cycle and adjusting the ON time accordingly (adding first or second constant time extensions), the system optimizes the inductor current slope and voltage drop during load transients without requiring complete redesign of the control architecture.
2Device complexity
If the ON time is constant and minimum OFF time is required, then the switching control is simple, but the duty cycle cannot be adjusted to higher ratio
Solution Approach 1:
The patent implements dynamic ON time extension based on duty cycle thresholds. When the duty cycle exceeds predetermined thresholds, the system automatically extends the ON time by adding first or second constant time periods, enabling the duty cycle to reach higher ratios (close to 100%) while maintaining simple switching control logic through standardized timing circuits.
Solution Approach 2:
The patent预先 sets up threshold comparison circuits that monitor the duty cycle and trigger ON time extensions before the duty cycle limitations are reached. This preliminary detection and response mechanism allows seamless extension of the duty cycle range without complex real-time calculations or additional switching control complexity.
3Productivity
If high switching frequency is used when input voltage is close to output voltage, then the voltage conversion is efficient, but large ripple occurs in output voltage
Solution Approach 1:
The patent adjusts the ON time parameter by adding constant time extensions based on duty cycle thresholds, which effectively changes the switching frequency and duty cycle characteristics. This parameter adjustment allows the system to maintain efficient voltage conversion while reducing output voltage ripple by optimizing the switching timing rather than simply increasing switching frequency.
Solution Approach 2:
The patent dynamically adjusts the ON time based on real-time duty cycle conditions, enabling the system to adaptively optimize the switching characteristics. This dynamic control allows efficient voltage conversion across different input-output voltage conditions while minimizing ripple by adjusting the timing parameters rather than relying solely on high switching frequency.
4Adaptability or versatility
If additional pins are added for VOS connection, then the ON time extension control is achieved, but the PCB layout complexity and cost increase
Solution Approach 1:
The patent merges the ON time extension control functionality into the existing control circuit by integrating threshold comparison and constant time generation within the existing switching regulator architecture. This consolidation achieves ON time extension capability without requiring additional external pins or separate control components, thereby reducing PCB layout complexity and cost.
Solution Approach 2:
The patent designs the control circuit to perform multiple functions: duty cycle monitoring, threshold comparison, constant time generation, and switch control signal generation, all within a single integrated control block. This multi-functionality eliminates the need for separate VOS pins and external compensation networks, simplifying the overall system design and PCB layout.
Data Source
AI summary
A dual constant time switching regulator includes: a power circuit including an inductor and at least a power switch for converting an input power to an output power, and a switching control circuit for generating a switch control signal to control the power switch, wherein the switching control circuit includes a comparison circuit for comparing an error amplified signal and a triangle wave signal to generate a comparison result, and a time determining circuit for generating the switch control signal according to the comparison result, wherein after the power switch turns ON, it keeps ON for at least a minimum ON time until the triangle wave signal is higher than the error amplified signal, and wherein after the power switch turns OFF, it keeps OFF for at least a minimum OFF time and until the triangle wave signal is lower than the error amplified signal.