Power Supply Switching Control Circuit for Noise Suppression
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Solution Overview
Problem
Power-supply devices experience spike noise and ineffective power consumption when switching between normal and standby modes due to current flow and parasitic capacitance charging, leading to malfunctions in peripheral circuits.
Innovation Solution
A power-supply device with a first and second power-supply circuit, switches, and a control circuit that manages voltage switching between the circuits to prevent simultaneous application of voltage values during mode changes, ensuring no current flows into the lower-voltage circuit, thereby preventing spike noise and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switching between power-supply circuits is performed by switches provided in the respective power-supply circuits, then power consumption is reduced in standby state, but spike noise is superimposed on the power-supply voltage due to current flow during switching
Solution Approach 1:
The control circuit sets the first switch to OFF state before the second switch is turned ON, and sets the first switch to ON state before the second switch is turned OFF. This preliminary action ensures that the higher-voltage power-supply circuit is completely disconnected before the lower-voltage circuit is connected, preventing current flow during switching and eliminating spike noise while maintaining power consumption reduction
2Loss of energy
If switching between power-supply circuits is performed by switches provided in the respective power-supply circuits, then power consumption is reduced in standby state, but ineffective power consumption occurs due to charging and discharging of parasitic capacitance
Solution Approach 1:
The control circuit coordinates the switching timing to set the first switch to OFF state before the second switch is turned ON, ensuring that no voltage difference exists between the power supply lines during transition. This preliminary action prevents charging and discharging of parasitic capacitance, eliminating ineffective power consumption while maintaining the power-saving standby mode
3Loss of energy
If the power-supply voltage generated in the standby power-supply circuit is lower than the power-supply voltage generated in the power-supply circuit for operation, then power consumption is reduced, but current flows into the lower-voltage circuit from the higher-voltage circuit during switching
Solution Approach 1:
The control circuit sets the first switch to OFF state before the second switch is turned ON, ensuring that the higher-voltage power-supply circuit is completely disconnected before the lower-voltage circuit is connected. This preliminary action eliminates the voltage difference that causes current flow during switching, while maintaining the lower voltage operation for power consumption reduction
Data Source
AI summary
Upon sending out a first power-supply voltage having a first value to first and second power supply lines in a first mode and sending out a second power-supply voltage having a second value lower than the first value to the second power supply line in a second mode, when switching a power-supply device from the first mode to the second mode, the value of the first power-supply voltage generated in a first power-supply circuit is changed to the second value first, the first and second power supply lines are temporarily connected together and then cut off from each other, and then the generating operation of the first power-supply voltage is stopped.