PWM Charge Pump Overcurrent Circuit for Stable Power-Switch Output
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Solution Overview
Problem
Conventional overcurrent protection circuits in power-switch circuits, particularly in USB Type-C systems, face issues with large output voltage ripples and instability due to the burst mode operation, which can lead to excessive power supply and prolonged suppression times affecting current ripples.
Innovation Solution
A PWM-based overcurrent protection circuit that dynamically adjusts the duty-cycle width of a charge pump using a pulse-width-modulation circuit to modulate the current flowing through a power switch, thereby suppressing overcurrent and reducing output voltage ripples by controlling the clock-voltage signal based on detected overcurrent conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If burst mode is used for overcurrent protection, then the current can be suppressed within a specific range, but large output voltage ripples occur and circuit stability deteriorates
Solution Approach 1:
The patent applies periodic action by using pulse-width modulation to generate periodic clock-voltage signals with adjustable duty cycles. The charge pump operates in periodic cycles, transferring charge in discrete steps rather than continuously, which smooths output voltage and reduces ripples while maintaining overcurrent protection capability
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the duty cycle of the charge pump based on real-time overcurrent detection. The control circuit modifies the clock-voltage signal parameters adaptively, changing the charge transfer amount in each cycle to optimize both protection performance and output stability under varying load conditions
2Reliability
If the clock-voltage signal hold time is extended for overcurrent protection, then current suppression is achieved, but excessive power is supplied and current ripple increases
Solution Approach 1:
The patent applies parameter changes by dynamically modifying the duty cycle parameter of the charge pump's clock-voltage signal. When overcurrent is detected, the duty cycle is reduced to limit power supply; when normal operation resumes, the duty cycle returns to normal levels. This parameter adjustment enables precise control of power delivery, preventing both overcurrent and excessive energy loss
Data Source
AI summary
A PWM-based (pulse width modulation-based) overcurrent protection circuit and an operating method for the same are provided. The PWM-based overcurrent protection circuit includes a pulse-width-modulation circuit that is connected to a charge pump and a load detection circuit of a power-switch circuit. The charge pump outputs a voltage to the power-switch circuit according to a clock-voltage signal. The load detection circuit is used to detect an overcurrent flowing through the power-switch circuit according to a load at an output end of the power-switch circuit. Thus, when the load detection circuit detects the overcurrent, the pulse-width-modulation circuit controls a duty-cycle width of the charge pump, so as to suppress the voltage outputted by the charge pump. Therefore, an output voltage from the power-switch circuit can be corrected for preventing or reducing the overcurrent.