Switching Power Supply Ripple Injection Offset Adjustment
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Solution Overview
Problem
Conventional switching power supply devices using nonlinear control methods face challenges in maintaining output voltage precision and load regulation characteristics when increasing ripple injection to improve switching action steadiness and jitter characteristics, particularly at high-efficiency and light load operations.
Innovation Solution
The solution involves a switching power supply device with a nonlinear control manner that includes a reference voltage generation portion, ripple injection portion, comparator, switching control portion, and offset adjustment portion. The offset adjustment portion generates an offset voltage based on the switch voltage and sets it to the reference or feedback voltage, allowing for increased ripple injection without degrading output voltage precision or load regulation, using specific resistor and capacitor configurations to optimize the ripple reference voltage generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of ripple injection is increased to improve steadiness of switching action and jitter characteristic, then the switching action steadiness is improved, but the precision of output voltage or load regulation characteristic deteriorates
Solution Approach 1:
The patent segments the reference voltage into two independent components: a DC component (from bandgap reference) and an AC ripple component (injected from switch node). This segmentation allows independent optimization of each component's amplitude without mutual interference, enabling large ripple injection for steady switching while maintaining precise DC output voltage through separate control of the DC reference component.
Solution Approach 2:
The patent introduces an intermediary coupling circuit (capacitor C1 and resistor R2) between the switch node and the reference voltage node. This intermediary selectively couples only the AC ripple component while blocking the DC component, allowing the ripple to be injected for improved switching steadiness without affecting the precision of the DC output voltage regulation.
2Reliability
If the amount of ripple injection is increased to improve jitter characteristic, then the jitter characteristic is improved, but the precision of output voltage deteriorates
Solution Approach 1:
The patent segments the reference voltage into independent DC and AC components, allowing the AC ripple component to be amplified for reduced jitter while the DC component maintains precise voltage regulation. The coupling circuit ensures only the AC component is injected, preventing degradation of DC output precision.
Solution Approach 2:
The coupling capacitor and resistor form an intermediary network that selectively passes AC ripple signals while blocking DC voltage. This allows large amplitude ripple injection for improved jitter characteristics without introducing DC offset that would degrade output voltage precision.
3Device complexity
If the DC value of reference voltage varies according to duty cycle, then the circuit operation is simplified, but the precision of output voltage deteriorates
Solution Approach 1:
The patent segments the reference voltage generation into independent DC and AC paths. The DC path uses a stable bandgap reference unaffected by duty cycle variations, while the AC path independently couples ripple from the switch node. This segmentation eliminates duty-cycle-induced DC offset while preserving the simplified nonlinear control operation.
Solution Approach 2:
The coupling capacitor acts as an intermediary that blocks DC variations caused by duty cycle changes while allowing AC ripple to pass. This prevents duty-cycle-dependent DC offset from reaching the comparator, maintaining output voltage precision while keeping the nonlinear control operation simple.
Data Source
AI summary
A switching power supply device of a nonlinear control manner is provided, which includes: a reference voltage generation portion, for generating a reference voltage; a ripple injection portion, for using a switch voltage at one end of a switch element to generate a ripple component, and injecting the ripple component into the reference voltage to generate a ripple reference voltage; a comparator, for comparing a feedback voltage corresponding to an output voltage with the ripple reference voltage; a switching control portion, for performing on/off control on the switch element based on an output signal of the comparator; and an offset adjustment portion for generating an offset voltage corresponding to the switch voltage, and setting any of the reference voltage, the feedback voltage, and the ripple reference voltage to the offset voltage.