PWM Controller Noise Filtering for Accurate Frequency Setting
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Solution Overview
Problem
Existing PWM controllers in power supply systems face issues with noise coupling from switching inductors and transistors, affecting the accuracy of external component-set parameters due to parasitic components, leading to incorrect parameter values.
Innovation Solution
A PWM controller design that incorporates a signal conditioning circuit to remove noise from the control voltage, using external resistors to set operating frequencies, and employs multiple timing circuits to selectively couple capacitors and minimize noise impact on clock signal adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If external components are used to set PWM controller parameters, then ease of operation is improved, but measurement precision deteriorates due to noise coupling from switching components
Solution Approach 1:
A noise filter circuit is introduced as an intermediary component between the external parameter-setting components (resistors, capacitors) and the PWM controller. This filter circuit removes switching noise from the power supply voltage before it reaches the external components, thereby maintaining parameter accuracy while preserving the ease of external configuration. The filter acts as a mediator that isolates the sensitive parameter-setting nodes from the noisy switching environment.
2Measurement precision
If noise filtering is added to protect external components, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The noise filter functionality is merged with existing power supply circuitry within the PWM controller. Rather than adding a completely separate filtering subsystem, the filter is integrated into the voltage regulation and power distribution paths that already exist in the controller. This consolidation achieves noise filtering without proportionally increasing device complexity, as shared components and circuits perform multiple functions.
3Productivity
If switching frequency is increased to improve power supply regulation, then productivity is improved, but object-generated harmful factors worsen due to increased noise generation
Solution Approach 1:
The switching noise generated by high-frequency operation is converted into a beneficial signal by using it to charge the filter capacitor in a controlled manner. The noise energy, which would normally be harmful, is instead utilized to maintain the voltage on the filter capacitor during switching transitions. This approach transforms the harmful noise into a useful charging mechanism, allowing high switching frequencies to be used for improved regulation efficiency without proportionally increasing noise interference.
Data Source
AI summary
In one embodiment, a PWM controller is configured to form a control signal that has reduced noise. The control signal is used to adjust a frequency of a clock signal of the PWM controller.