Switching Power Supply Starting Circuit Zero Standby Consumption
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Solution Overview
Problem
Conventional switching power supplies experience significant power loss in no-load mode due to high self-power consumption of power management chips, static current in semiconductor elements, and large starting resistor power consumption, lacking solutions for reducing no-load power consumption to several milliwatts and directly turning off the VCC power supply.
Innovation Solution
A starting circuit for switching power supplies incorporating an input rectifying and filtering circuit, a transformer with primary, secondary, and feedback coils, a photoelectric coupler to control the power management chip and transformer, and a battery detection circuit to achieve zero or near-zero power consumption in standby mode by using a field effect transistor and photoelectric couplers to manage power states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional power management chip is used, then the power supply can be controlled, but the self power consumption is large causing high no-load power loss
Solution Approach 1:
The patent extracts the power management function from the conventional integrated power management chip and implements it through a combination of simple components including a startup circuit, photoelectric coupler, and basic control elements. This separation allows the main control chip to be completely powered off in standby mode while still providing necessary power management functions through the external circuitry.
Solution Approach 2:
The startup circuit is designed to automatically detect the presence of input voltage and autonomously generate the initial power supply voltage for the control chip without requiring continuous power management. The circuit self-regulates by detecting voltage thresholds and controlling the photoelectric coupler accordingly, eliminating the need for a continuously powered management chip.
2Loss of energy
If the power management chip is completely turned off to achieve zero power consumption, then no-load power loss is reduced, but the ability to control and manage power supply is lost
Solution Approach 1:
The startup circuit performs preliminary actions by automatically detecting input voltage presence and generating the initial power supply voltage before the control chip needs to operate. This pre-powering mechanism ensures the control chip can be fully powered off during standby while the startup circuit remains ready to restore power when needed, maintaining control capability without continuous power consumption.
3Reliability
If a large starting resistor is used to ensure reliable startup, then the power supply can start reliably, but the power consumption of the starting resistor becomes too large
Solution Approach 1:
The patent employs a dynamic startup mechanism where the photoelectric coupler's output impedance changes based on the presence or absence of input voltage. When input voltage is present, the photoelectric coupler conducts and provides low impedance for reliable startup. When input voltage is absent, the photoelectric coupler blocks and presents high impedance, minimizing power consumption during standby. This dynamic impedance adjustment resolves the contradiction between startup reliability and power consumption.
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 effectively reduces standby power consumption to zero, improving efficiency and extending the service life of the charger by ensuring zero power usage when not in use, thereby reducing resource waste and enhancing safety and reliability.
Implementation Method 1
a first photoelectric coupler which is connected with an output end of the starting circuit and an external battery respectively; after the first photoelectric coupler is powered on, the starting circuit is turned on, and the power management chip and the transformer are started and work
Data Source
AI summary
The disclosure provides a starting circuit of a switching power supply, which includes an input rectifying and filtering circuit, a starting circuit, a transformer, an output rectifying and filtering circuit, a feedback circuit, a first photoelectric coupler and a power management chip. The power management chip is respectively connected with the output end of the first photoelectric coupler, the output end of the feedback circuit and the primary coil of the transformer. After the first photoelectric coupler is powered on, the starting circuit is turned on, and the power management chip and the transformer are started and work. After the first photoelectric coupler is powered off, the power management chip stops working and enters a standby state. And at the moment, the standby power consumption of the power management chip is equal to zero.