Capacitance Amplifying Circuit for Power Converter Controller Integration
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Solution Overview
Problem
In highly integrated power convertors, the external compensation capacitor and compensation pin increase costs, and existing solutions fail to integrate these components effectively, leading to issues with compensation voltage stability when the dimming signal is disabled due to offset and leakage within the transconductance amplifying unit.
Innovation Solution
A capacitance amplifying circuit with a comparison unit and a capacitance amplifying module that generates an equivalent capacitor, changing the closed loop to an open loop when the dimming signal is disabled, allowing the capacitance amplifying module to maintain a fixed compensation voltage by amplifying the capacitance of a reference capacitor, thus removing the need for an external compensation capacitor and pin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an external compensation capacitor and compensation pin are used in the controller, then the compensation voltage can be generated according to the external compensation capacitor and reference voltage, but the cost of the controller increases and the integration is reduced
Solution Approach 1:
The patent merges the external compensation capacitor function into an internal capacitance amplifying module, combining the compensation capacitor, compensation pin, and related circuitry into a single integrated unit within the controller. This eliminates the need for separate external components while maintaining the compensation voltage generation function.
Solution Approach 2:
The capacitance amplifying module serves multiple functions: it generates the equivalent capacitor, amplifies the capacitance value, regulates the compensation voltage, and replaces the traditional compensation pin. This multi-functional design reduces the number of external components needed.
2Reliability
If the closed loop is maintained when the dimming signal is disabled, then the transconductance amplifying unit continues to operate, but the compensation voltage continuously increases or decreases due to offset and leakage
Solution Approach 1:
The patent dynamically switches the closed loop between enabled and disabled states based on the dimming signal status. When the dimming signal is enabled, the closed loop is active for accurate compensation voltage generation. When disabled, the closed loop is turned off to prevent offset and leakage effects, with the open loop maintaining a fixed compensation voltage for stable transient response.
Solution Approach 2:
The patent uses feedback control through the closed loop when the dimming signal is enabled to accurately regulate the compensation voltage according to the equivalent capacitor and reference voltage. The feedback mechanism is selectively activated only when needed, preventing the instability issues that would occur if it remained continuously active.
3Quantity of substance
If the capacitance of the reference capacitor is amplified, then the equivalent capacitor can be generated with K times the capacitance value, but the circuit complexity increases
Solution Approach 1:
The patent changes the capacitance parameter by using a capacitance amplifying module that multiplies the reference capacitor's capacitance by a factor of K. This parameter transformation allows a small internal reference capacitor to function as a larger equivalent capacitor, eliminating the need for large external components while maintaining the required capacitance value.
Data Source
AI summary
A capacitance amplifying circuit applied to a controller of a power convertor includes a comparison unit and a capacitance amplifying module. The comparison unit receives a feedback voltage corresponding to a load coupled to the power convertor, a dimming signal, and a reference voltage, and outputs a compensation current. The capacitance amplifying module generates an equivalent capacitor. A capacitance of the equivalent capacitor is K times to a capacitance of a reference capacitor of the capacitance amplifying module, and K is a real number greater than 1. The compensation current and the equivalent capacitor are used for determining a compensation voltage, and when the dimming signal is disabled, a closed loop within the capacitance amplifying module is changed to an open loop to keep the compensation voltage at a fixed value.