Power Supply Feedback Switching for Faster Load Transients
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Solution Overview
Problem
Switching mode power supplies face challenges in achieving fast transient response under heavy and light loading conditions due to saturation recovery of the compensation network and slew rate limitations of the error amplifier, leading to degraded system performance during step load transients.
Innovation Solution
A power supply controller with an active feedback switch that opens and closes the feedback loop, acting as an active compensator, reducing the error amplifier's slew-rate requirement and allowing passive charge storage elements to maintain charge, enabling quick recovery between continuous and pulse skip modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power supply controller operates in continuous mode under heavy load conditions, then the system can handle large current demands, but the transient response is degraded due to saturation recovery of the compensation network and slew rate limitation of the error amplifier
Solution Approach 1:
The patent implements dynamic switching between continuous conduction mode (CCM) and pulse skip mode based on load conditions. The controller dynamically adjusts the operating mode to optimize both power handling and transient response characteristics, transitioning from CCM under heavy load to pulse skip mode under light load conditions
Solution Approach 2:
The patent changes the operating parameters of the power supply controller by implementing pulse skip mode, which modifies the switching behavior and duty cycle characteristics. This parameter change allows the system to achieve faster transient response by preventing compensation network saturation and reducing error amplifier slew rate requirements during mode transitions
2Loss of energy
If the power supply controller operates in pulse skip mode under light loading conditions, then power consumption is reduced, but the transient response is degraded due to saturation recovery of the compensation network
Solution Approach 1:
The controller dynamically switches between pulse skip mode for light load power savings and continuous mode for fast transient response. The mode selection is based on real-time load detection, enabling the system to optimize power consumption during light loading while maintaining rapid response capability when load changes occur
Solution Approach 2:
The patent prepares the compensation network and error amplifier for quick recovery by designing the circuit to minimize saturation effects during pulse skip mode operation. The compensation network is configured to recover rapidly from saturation, enabling fast transition back to continuous mode when load conditions change
3Stability of the object's composition
If a compensation network is connected to an error amplifier to stabilize the system, then system stability is improved, but the transient response is limited due to slew rate limitation of the error amplifier
Solution Approach 1:
The patent implements pulse skip mode operation which changes the operating parameters of the error amplifier and compensation network. By operating in discontinuous conduction mode, the error amplifier experiences reduced slew rate requirements, allowing the compensation network to respond faster during transient events while maintaining stability through proper compensation design
Data Source
AI summary
A power supply controller and method for improving the transient response of the power supply controller. The power supply controller includes a pulse width modulation control module connected to a feedback network. The feedback network is composed of an amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal. A compensation network is coupled between the inverting input terminal and the output terminal of the amplifier and a reference voltage is coupled to the non-inverting input terminal of the amplifier. A switch is coupled between the output terminal of the amplifier and an input terminal of the compensation network. The transient response of the controller is improved by operating the controller in a closed loop compensation configuration during a continuously pulsing operating mode and in an open loop compensation configuration during a pulse skip operating mode.