Common Control for Power Converter PWM and PFM Modes
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Solution Overview
Problem
Power delivery circuits operating under light load conditions using discontinuous conduction mode (DCM) and pulse frequency modulation (PFM) control often experience instability, leading to audible buzzing due to over-regulation and voltage ripple, which compromises efficiency and user experience.
Innovation Solution
A circuit design that incorporates both PWM and PFM regulation circuits based on a common control signal, with a voltage-controlled oscillator (VCO) and programmable current sink to ensure seamless transitions between control modes, reducing audible noise and maintaining efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If PFM control is used under light load conditions, then efficiency is improved, but stability deteriorates causing audible buzzing
Solution Approach 1:
The system dynamically switches between PFM and PWM control modes based on load conditions. The controller monitors load level and automatically transitions from PFM (efficient but unstable) to PWM (stable but less efficient) as load increases, and vice versa, optimizing both efficiency and stability across different operating conditions
Solution Approach 2:
The system changes the control parameter from frequency modulation (PFM) to pulse width modulation (PWM) based on operating conditions. By altering the control mechanism parameter, the system achieves stable operation under light loads while maintaining efficiency, and transitions to stable PWM control under heavy loads where efficiency is less critical
2Adaptability or versatility
If both PWM and PFM control circuits are implemented, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent merges PWM and PFM control circuits into a unified controller that can operate in either mode. The control circuit integrates both PWM generation and PFM frequency modulation capabilities, with a single controller managing both control strategies and automatically selecting the appropriate mode based on load conditions, thereby reducing overall system complexity while maintaining adaptability
Data Source
AI summary
Aspects of the disclosure provide for a circuit. In some examples, the circuit includes an amplifier having a first input configured to receive a signal representative of a condition related to a power converter, a second input configured to receive a reference signal, and an output, a PWM regulation circuit having an input coupled to the output of the amplifier, a first output configured to provide a first control signal for a high-side transistor of the power converter, and a second output configured to output a first control signal for a low-side transistor of the power converter, and a PFM regulation circuit having an input coupled to the output of the first amplifier, a first output configured to output a second control signal for the high-side transistor of the power converter, and a second output configured to output a second control signal for the low-side transistor of the power converter.