PWM Controller VDD Charging Feedback for Undervoltage Stability
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Solution Overview
Problem
Conventional power converters face challenges in efficiently providing stable power to pulse-width-modulation (PWM) controllers during startup and normal operation, particularly under dynamic and no-load conditions, leading to potential undervoltage protection and inefficient power consumption.
Innovation Solution
Implementing a controller with a voltage detector and charging current generator to monitor and adjust the power supply to PWM controllers, ensuring stable voltage levels by generating charging currents when thresholds are met, thereby maintaining consistent power to the PWM controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional power converters use a high-voltage pin to charge an external capacitor during startup, then the startup process is accelerated and power consumption after startup is reduced, but the power stability to the PWM controller during normal operation becomes insufficient under dynamic and no-load conditions
Solution Approach 1:
The patent implements a feedback mechanism where the PWM controller monitors the voltage at its VDD pin and dynamically controls the charging current from the high-voltage pin. When the VDD voltage drops below a threshold during normal operation (especially under no-load or dynamic conditions), the controller activates the internal charging circuit to replenish the capacitor, ensuring stable power supply without excessive power consumption during steady-state operation.
Solution Approach 2:
The patent transitions from a static charging approach (charging only during startup) to a dynamic charging approach where the charging circuit remains active but controllable during normal operation. The charging current is dynamically adjusted based on real-time voltage conditions, allowing the system to adapt to varying load conditions and maintain power stability while optimizing power consumption.
2Loss of energy
If the internal charging circuit is disconnected after startup threshold is reached, then power consumption is reduced, but undervoltage protection may be triggered during normal operation under varying load conditions
Solution Approach 1:
The PWM controller continuously monitors the VDD pin voltage and uses this feedback to determine when to activate or deactivate the internal charging circuit. This closed-loop control ensures that the charging circuit remains inactive during stable operation (minimizing power loss) but activates promptly when voltage drops indicate potential undervoltage conditions, preventing false protection triggers while maintaining energy efficiency.
3Device complexity
If power is provided to PWM controller only during startup through high-voltage pin, then startup process is simplified, but power stability under dynamic and no-load conditions during normal operation deteriorates
Solution Approach 1:
The patent makes the high-voltage pin and internal charging circuit serve dual functions: they operate during startup to charge the VDD capacitor as in conventional designs, but they also remain available during normal operation to provide supplemental charging when needed. This multi-functionality allows the same hardware to address both startup requirements and ongoing power stability needs without increasing device complexity.
Data Source
AI summary
Controller and method for a power converter. For example, the controller includes: a first terminal configured to receive a first voltage; a second terminal connected to a capacitor and biased to a second voltage; a voltage detector configured to receive the second voltage from the second terminal and generate a detection signal based at least in part on the second voltage; a charging controller configured to receive the detection signal and generate a first control signal based at least in part on the detection signal; and a charging current generator configured to receive the first voltage from the first terminal and receive the first control signal from the charging controller; wherein the voltage detector is further configured to: detect that the second voltage has decreased to a first predetermined threshold; and generate the detection signal indicating that the second voltage has decreased to the first predetermined threshold.