Switching Power Supply Standby Signal Detection
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Solution Overview
Problem
Conventional switching power supply apparatuses require a specialized circuit to transmit standby control signals from the secondary side to the primary side, increasing costs due to the need for a dedicated terminal and circuit elements for signal transmission in an electrically insulated state.
Innovation Solution
The apparatus eliminates the need for a secondary-side to primary-side signal transmission circuit by using a control IC on the primary side that monitors the output voltage and resonance current to switch between normal and standby modes based on the standby control signal, without a dedicated terminal for receiving the signal, allowing indirect detection and control of the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a specialized circuit is used to transmit standby control signals from secondary side to primary side, then signal transmission reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the standby control signal detection function from a separate specialized circuit and integrates it into the existing control IC on the primary side. The control IC monitors the operating frequency and load signal to indirectly detect the standby control signal, eliminating the need for dedicated signal transmission circuitry between secondary and primary sides.
Solution Approach 2:
The control IC on the primary side is designed to perform multiple functions: it controls the switching elements, monitors the operating frequency, detects the load signal, and now also detects the standby control signal indirectly. This multi-functionality eliminates the need for separate specialized circuits for signal transmission.
2Adaptability or versatility
If a dedicated terminal is added for receiving standby control signal, then signal reception capability is improved, but device complexity and cost increase
Solution Approach 1:
The control IC's existing terminals are utilized for multiple purposes. The terminals that previously only monitored operating frequency and load signals now also serve to indirectly detect the standby control signal through changes in these parameters, eliminating the need for a dedicated terminal.
Solution Approach 2:
The control IC uses its own monitoring capabilities to detect the standby control signal indirectly through changes in operating frequency and load characteristics, rather than requiring external dedicated terminals for signal reception.
3Ease of manufacture
If standby control signal transmission circuit is eliminated, then cost is reduced, but signal detection capability may be affected
Solution Approach 1:
The control IC continuously monitors the operating frequency and load signal as feedback parameters. When a standby control signal is applied to the secondary side, it causes changes in these feedback parameters, which the control IC detects to determine the standby mode status.
Solution Approach 2:
The patent detects the standby control signal by monitoring changes in existing electrical parameters (operating frequency and load signal) rather than directly detecting the standby control signal itself. The standby control signal causes measurable changes in these parameters that the control IC can detect.
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
This solution reduces costs by eliminating the need for a secondary-side to primary-side signal transmission circuit and allows for efficient switching between normal and standby modes, improving power efficiency and reducing standby power consumption.
Implementation Method 1
The magnetizing inductance of the primary winding P1 of the transformer T1, leakage inductance between the primary winding P1 and secondary windings S1 and S2, and the resonance capacitor C5 make up a resonance circuit
Data Source
AI summary
In a standby signal generation circuit, a first comparator compares a FB voltage fed back from a secondary side with a first reference voltage, and a second comparator compares a signal indicative of the magnitude of a load with a second reference voltage. When the FB voltage falls under the first reference voltage, the first comparator sets an RS flip-flop via a first delay circuit. At this time, if the signal is lower than the second reference voltage and a reset signal is not inputted to the RS flip-flop, it is determined, based on a standby control signal from the load, that an output voltage of a switching power supply apparatus has fallen. Accordingly, a standby signal indicative of standby mode is outputted via a second delay circuit. If the signal transiently exceeds the second reference voltage, the standby signal is set to normal mode.