Charge Pump Switch Control Circuit Ripple Reduction
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Solution Overview
Problem
Conventional charge pumps experience power loss and output current ripple issues, and start-up overshoot problems in high input voltage scenarios due to energy storage and transfer inefficiencies.
Innovation Solution
A charge pump design incorporating diodes and capacitors that bypass unnecessary charging, using a zener diode to maintain a constant power supply voltage and reduce power consumption, along with a switch control circuit that generates a ripple reduction signal to manage input voltage peaks and modulate switching operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional charge pump stores energy proportional to line input voltage, then energy is stored in the capacitor, but power loss occurs according to the peak of the line input voltage
Solution Approach 1:
The control circuit performs preliminary detection of the input voltage peak and generates a control signal before the charging phase. This preliminary action allows the charge pump to adjust its charging behavior in advance, preventing excessive energy storage that would lead to power loss during the peak voltage period.
Solution Approach 2:
The control circuit continuously monitors the input voltage and uses feedback to adjust the charging control signal. When the input voltage approaches the peak, the feedback mechanism reduces the charging duty cycle, thereby optimizing energy storage efficiency and minimizing power loss in real-time.
2Reliability
If a large capacitor is used to remove ripple according to line frequency, then ripple is reduced, but the capacitor size becomes large
Solution Approach 1:
The control circuit detects the line frequency and generates preliminary control signals synchronized with the AC cycle. By anticipating the ripple pattern and adjusting the charging duty cycle in advance, the system reduces output ripple without requiring an oversized capacitor.
Solution Approach 2:
The charging duty cycle is dynamically adjusted based on the detected input voltage and line frequency. The control circuit varies the charging parameters in real-time to match the AC waveform, enabling effective ripple reduction with a smaller capacitor compared to fixed-duty-cycle designs.
3Use of energy by moving object
If the switch is turned on continuously to store energy, then energy is stored from input source, but ripple of output current increases
Solution Approach 1:
The control circuit implements periodic charging cycles synchronized with the AC line frequency. Instead of continuous switching, the charge pump operates in periodic phases of charging and transferring energy, which naturally reduces output current ripple while maintaining effective energy storage from the input source.
Solution Approach 2:
The control circuit ensures continuous useful action by overlapping the charging and transferring phases. Energy storage and transfer operations are coordinated to maintain continuous power delivery to the load, reducing gaps that would cause current ripple while optimizing overall energy transfer efficiency.
4Device complexity
If detected input voltage is directly used in current mode control, then control is simplified, but start-up overshoot problem occurs in high input voltage
Solution Approach 1:
The control circuit performs preliminary detection and processing of the input voltage to generate a scaled or clamped control signal before it reaches the current mode controller. This preliminary action prevents high input voltage from directly causing overshoot while maintaining relatively simple control architecture.
Solution Approach 2:
The control circuit transforms the input voltage parameter through scaling, clamping, or offset operations to create a control signal with appropriate amplitude range. This parameter transformation ensures that even high input voltages produce controlled start-up behavior without requiring complex control logic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces power loss, minimizes output current ripple, and prevents start-up overshoot by optimizing energy transfer and storage, allowing for efficient operation of control ICs without unnecessary charging.
Implementation Method 1
a zener diode coupled in parallel to the third diode and the power supply capacitor
Implementation Method 2
a pump capacitor coupled to a third node to which the first diode and the second diode are coupled
Implementation Method 3
a first diode coupled to a first node; a second diode coupled to a second node; a third diode coupled between the pump capacitor and the power supply capacitor
Data Source
AI summary
A charge pump includes: a first diode that is connected to a first node; a second diode that is connected to a second node; a pump capacitor that is connected to a third node to which the first diode and the second diode are connected; a power supply capacitor that is connected to the pump capacitor; a third diode that is connected between the pump capacitor and the power supply capacitor; and a zener diode that is connected in parallel to the third diode and the power supply capacitor. A power supply device decreases a ripple of an output current using a ripple reduction signal.