Switching Power Supply Soft Start via Dynamic Triangle Bias
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Solution Overview
Problem
Constant on time control in switching power supply systems is limited by fixed DC bias, which constrains output voltage range and hinders integration of soft start functions, and results in poor transient response during discontinuous-current mode operation.
Innovation Solution
A switching power supply system with a feedback circuit, error amplifier, triangle signal generator, and constant on time control circuit that uses a soft start signal to dynamically adjust the DC bias of the triangle signal, allowing it to match with the error signal, thereby expanding the output voltage range and improving transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed DC bias is used in the triangle signal to match the error signal amplitude, then the amplitude matching is achieved, but the output voltage range is constrained and soft start function integration becomes difficult
Solution Approach 1:
The patent applies the dynamics principle by transforming the fixed DC bias into a dynamic, adjustable bias signal. The triangle signal generator now receives a controllable bias input that can be adjusted according to different operating conditions, allowing the system to adapt to various output voltage requirements and integrate soft start functionality without compromising amplitude matching precision.
Solution Approach 2:
The patent implements parameter changes by making the DC bias parameter of the triangle signal variable rather than fixed. By allowing the bias parameter to be dynamically adjusted based on operating conditions, the system achieves both precise amplitude matching and enhanced adaptability for different output voltages and soft start requirements.
2Stability of the object's composition
If the error signal is required to change smoothly for system stability, then system stability is maintained, but transient response performance deteriorates during discontinuous-current mode when power switches are turned off
Solution Approach 1:
The patent applies dynamics by enabling the error signal to exhibit different behavior characteristics under different operating conditions. During continuous conduction mode, the error signal changes smoothly to maintain stability, while during discontinuous-current mode, the error signal can change more rapidly to improve transient response, achieving adaptive performance optimization.
Solution Approach 2:
The patent implements parameter changes by allowing the error signal's change rate parameter to be dynamically adjusted based on the operating mode. This enables the system to switch between smooth error signal changes for stability and faster error signal changes for improved transient response during discontinuous-current operation.
Data Source
AI summary
A switching power supply system includes a switching converter, to convert an input voltage into an output voltage and to generate a switching signal; a feedback circuit, to generate a feedback signal; an error amplifier to generate an error signal; a triangle signal generator to generate a triangle signal; a constant on time control circuit to receive error signal and the triangle signal, and to generate a constant on time control signal to control power switch; in the system. The triangle signal has a DC bias based on either a soft start signal or a second reference signal. The system could perform soft start function and meanwhile keep matching between the error signal and the triangle signal.