Charge Pump Power Supply With Load-Adaptive Clock Frequency
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Solution Overview
Problem
Conventional charge pump circuits experience decreased electric power efficiency and output voltage when operated at either light or heavy loads due to fixed high operation frequencies, leading to inefficiencies and reduced performance.
Innovation Solution
A power supply with a charge pump circuit that varies the frequency of a clock signal based on the current flowing through the load, using an output current detection circuit and frequency conversion circuit to adjust the clock signal frequency according to load conditions, ensuring optimal operation across different load magnitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the charge pump circuit operates at a fixed high frequency, then the output voltage is maintained at heavy loads, but the electric power efficiency decreases at light loads
Solution Approach 1:
The charge pump circuit dynamically adjusts its operation frequency based on load conditions. At heavy loads, it operates at high frequency to maintain sufficient voltage stepping capability. At light loads, it automatically reduces the operation frequency to avoid unnecessary switching losses, thereby optimizing electric power efficiency across varying load conditions
Solution Approach 2:
The operation frequency parameter of the charge pump circuit is changed according to load magnitude. The circuit detects load conditions and adjusts the clock signal frequency accordingly - using high frequency for heavy loads to ensure adequate voltage transformation, and low frequency for light loads to minimize energy loss from excessive switching operations
2Loss of energy
If the charge pump circuit operates at a low frequency, then the electric power efficiency improves at light loads, but the output voltage decreases at heavy loads
Solution Approach 1:
The charge pump circuit employs dynamic frequency adjustment where the operation frequency is not fixed but adapts to load requirements. The control circuit monitors load conditions and switches between high and low frequency modes, ensuring that low frequency is used only when appropriate for light loads, while high frequency is activated when heavy loads require sufficient voltage output
3Speed
If the charge pump circuit uses unduly high-speed operation, then the response time is fast, but the electric power efficiency decreases due to excessive switching
Solution Approach 1:
The charge pump circuit uses periodic switching action controlled by a clock signal, but the frequency of this periodic action is dynamically adjusted. Instead of continuous high-speed switching, the circuit employs periodic switching at an optimized frequency that matches the actual load requirements, reducing unnecessary switching events while maintaining adequate response performance
Data Source
AI summary
The power supply of the present invention is composed of: a charge pump circuit (54) that periodically turns on and off a plurality of charge-transfer switches (Q1 to Q4) according to clock signals (c1 and c2), thereby charges and discharges a charge storage capacitor (C1) and thus produces the desired output voltage (Vo) from an input voltage (Vi) to supply it to a load (LED); an output current detection circuit 57 for detecting an output current Io (a reference current (Im) thereof in FIG. 1) to the load; and means (a frequency conversion circuit 52 in FIG. 1) that varies the frequency of the clock signals c1 and c2 based on the result of the detection of the output current Io. With this configuration, it is possible to achieve high electric power efficiency irrespective of the magnitude of a load.