Power Supply Voltage Control for Low Consumption Mode
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Solution Overview
Problem
Conventional power supplies face challenges in reducing consumption power in low consumption modes while maintaining voltage accuracy, particularly due to the risk of output voltage decrease caused by the on-resistance of FETs and coil resistive components, and the need for additional power supply circuits to drive high-side FETs at 100% ON-duty.
Innovation Solution
A power supply system comprising a first power supply to convert AC voltage to a first DC voltage, a second power supply to step down the voltage in a low consumption mode, and a third power supply for constant voltage control, with a control unit managing the transitions between states to maintain voltage accuracy and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the input voltage to the step-down DC/DC converter is decreased and the ON-duty of the high-side FET is set at 100% to reduce switching loss, then the consumption power in low consumption mode is reduced, but the output voltage decreases due to on-resistance of the FET and coil resistive component, decreasing voltage accuracy
Solution Approach 1:
The patent changes the operating parameters of the DC/DC converter by adjusting the input voltage level and the ON-duty cycle of the high-side FET. Specifically, it sets the ON-duty at 100% and decreases input voltage to minimize switching losses while managing the resulting voltage drop through controlled impedance design of the power path.
Solution Approach 2:
The patent uses a synchronous rectification topology where a low-side FET copies the rectification function traditionally performed by a diode, enabling bidirectional current flow and improved efficiency. This synchronous operation allows for better control of voltage drops across the power path components.
2Productivity
If an N channel FET with lower on-resistance is used as the high-side FET to improve efficiency, then the step-down DC/DC converter efficiency is improved, but an additional power supply circuit is required to generate voltage higher than input voltage to drive the high-side FET at 100% ON-duty
Solution Approach 1:
The patent introduces a bootstrap circuit as an intermediary power supply mechanism that generates the required gate drive voltage for the high-side N-channel FET. This bootstrap circuit uses the existing input voltage and switching action to create a voltage boost, eliminating the need for an external high-voltage power supply while enabling 100% ON-duty operation.
Solution Approach 2:
The bootstrap circuit is self-regenerating, using the switching action of the converter itself to recharge the bootstrap capacitor. This self-service mechanism provides continuous gate drive voltage without external intervention, maintaining the high-side FET at 100% ON-duty while avoiding additional complex power supply requirements.
3Device complexity
If the input voltage is close to the target voltage of the output voltage and no additional power supply circuit is provided, then the device complexity is reduced, but the output voltage decreases and fails to provide targeted output voltage
Solution Approach 1:
The patent adjusts the input voltage parameter to be deliberately lower than the target output voltage, creating a sufficient voltage headroom that compensates for the voltage drops across the FET on-resistance and coil resistive component. This parameter optimization ensures the output voltage reaches the target value even with minimal impedance losses.
Solution Approach 2:
The patent performs preliminary voltage drop compensation by selecting appropriate input voltage levels and FET on-resistance values before operation. The design pre-calculates and pre-compensates for the expected voltage drops, ensuring the output voltage accuracy is maintained without requiring complex feedback or additional power supply circuits.
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 system effectively reduces consumption power in low consumption modes while maintaining voltage accuracy by using a combination of power supplies and control units to manage voltage transitions and prevent output voltage drops.
Implementation Method 1
a first power supply unit configured to convert AC voltage into a first DC voltage
Implementation Method 2
convert AC voltage into a first DC voltage and output the first DC voltage
Implementation Method 3
a second power supply unit configured to convert the first DC voltage output from the first power supply into a second DC voltage lower than the first DC voltage in the first state
Implementation Method 4
a third power supply unit configured to stop operation in the first state, the third power supply unit configured to operate to perform constant voltage control such that the second DC voltage is a target voltage when the first state transitions to the second state
Data Source
AI summary
The power supply is capable of operating in a first state and a second state having a consumption power lower than a consumption power of the first state. The power supply controls a first power supply in the first state such that a first DC voltage is a first voltage and controls the first power supply in the second state such that the first DC voltage is a second voltage lower than the first voltage.