DC-DC Converter Duty Ratio Data Retention Using Oxide Semiconductor
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Solution Overview
Problem
DC-DC converters in portable electronic devices face challenges in reducing power consumption, particularly when stopping the supply of power voltage, as the off-state current of transistors leads to instability in output voltage and requires external memory for duty ratio data storage, making it unsuitable for short power-off periods.
Innovation Solution
A DC-DC converter with a control circuit that includes a memory device with a capacitor for storing duty ratio data and a transistor with a wider band gap semiconductor, allowing for low off-state current and internal data storage, enabling the power supply voltage to be stopped temporarily without losing data and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply voltage is stopped to reduce power consumption, then power consumption is reduced, but the duty ratio data is lost and output voltage becomes unstable
Solution Approach 1:
The patent extracts the duty ratio data storage function from the volatile memory of the DSP and places it in a non-volatile memory device, separating the data retention requirement from the power supply requirement. This allows the DSP to be powered down while the duty ratio data persists in the non-volatile memory, resolving the contradiction between power consumption reduction and output voltage stability.
2Loss of information
If external non-volatile memory is used to store duty ratio data, then data retention during power-off is achieved, but the system complexity increases and restoration time is extended
Solution Approach 1:
The patent combines the non-volatile memory device with the control circuit in an integrated manner, where the memory device is directly coupled to the control circuit. This integration reduces the complexity compared to using separate external memory systems and enables faster data restoration by eliminating additional interface and communication overhead.
3Use of energy by moving object
If the DSP is stopped by stopping clock signal supply, then power consumption is reduced, but off-state current continues to consume power
Solution Approach 1:
The patent implements preliminary action by saving the duty ratio data to the non-volatile memory device before stopping the DSP. This preliminary data preservation enables the system to completely power down the DSP (including removing clock signals and power supply voltage) without risking data loss, thereby eliminating off-state current consumption while maintaining system functionality upon restart.
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 allows for low power consumption and stable output voltage in portable devices by minimizing off-state current and eliminating the need for external memory, enabling short power-off periods without data loss.
Implementation Method 1
a transistor with a channel formation region including a semiconductor whose band gap is wider than that of silicon and whose intrinsic carrier density is lower than that of silicon
Data Source
AI summary
A DC-DC converter includes a control circuit, a switching element, and a constant-voltage generation portion which generates an output voltage on the basis of an input voltage supplied through the switching element. The control circuit includes AD converters which convert the input voltage and the output voltage, a signal processing circuit, a pulse modulation circuit, and a power supply control circuit which controls supply of a power supply voltage to the signal processing circuit in accordance with digital values of the input voltage and the output voltage. The signal processing circuit determines the duty ratio in accordance with the digital value of the output voltage, and the pulse modulation circuit controls the switching element. The signal processing circuit includes a memory device including a memory element, a capacitor for storing data of the memory element, and a transistor for controlling charge in the capacitor. The transistor includes an oxide semiconductor.