Low Standby Isolated Power Supply Circuit for LED Drivers
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Solution Overview
Problem
Traditional LED driver designs fail to meet the low standby power requirements of modern lighting markets, as they either consume high power when operational during standby mode or are unable to power auxiliary sensors and transition from standby to normal operation effectively.
Innovation Solution
A low standby isolated power supply circuit is introduced, comprising a primary and secondary side circuit with a switch, input resistor, and opto-couplers, which selectively powers integrated circuits and auxiliary loads based on operational status, using a power processing circuit with a PFC stage and isolated DC-DC converter stage to minimize power consumption during standby mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LED driver components are operational during standby mode to maintain power to auxiliary devices and controller, then auxiliary devices can be powered, but power consumption is unacceptably high (about 2-3 W)
Solution Approach 1:
The power supply system is segmented into multiple independent power paths: a main power path for high-power operation and a separate low-power standby path. During standby mode, only the low-power path remains active, providing just enough power for the controller and auxiliary devices while keeping the main power-consuming components disabled. This segmentation allows the system to meet both the reliability requirement of powering auxiliary devices and the energy efficiency requirement of low standby consumption.
2Use of energy by moving object
If LED driver components are disabled during standby mode to reduce power consumption, then standby power is reduced, but the LED driver is unable to power auxiliary sensors or determine when to transition from standby to normal operation
Solution Approach 1:
A low-power intermediary power path is introduced as a mediator between complete shutdown and full operation. This intermediary path provides minimal but sufficient power to keep the controller and auxiliary sensors functional during standby mode, enabling them to detect occupancy changes and trigger transition to normal operation. The intermediary power path uses efficient power management techniques to maintain functionality while consuming less than 0.5 W, resolving the contradiction between power reduction and functionality maintenance.
3Device complexity
If traditional LED driver designs are used, then the design is simple, but the standby power consumption exceeds market requirements (greater than 0.5 W)
Solution Approach 1:
The power supply architecture is made dynamic by implementing mode-dependent power paths that automatically switch between standby mode and normal operation mode. The system dynamically adjusts which power paths are active based on the operational state, using simple control logic to transition between modes. This dynamic approach allows the circuit to maintain simplicity while achieving low standby consumption through automatic power path selection rather than complex continuous control.
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 achieves low standby power consumption, enabling the LED driver to maintain functionality of auxiliary sensors while reducing power usage to less than 0.5 W, allowing for efficient transition between standby and normal operation modes.
Implementation Method 1
a first opto-coupler having a first phototransistor side and a first diode side, the first opto-coupler coupled between the first input resistor and a gate of the switch
Data Source
AI summary
An LED driver is configured to minimize power consumption during standby operating modes. The LED driver includes power factor correction (PFC) and isolated DC-DC conversion stages, driven by respective first and second regulators. An auxiliary sensor detects environmental conditions for a controller which generates standby or normal operating mode signals based thereon. A low standby isolated power supply circuit receives operating mode signals and is configured: responsive to normal operating mode signals to enable the voltage regulators; responsive to standby mode signals to disable the voltage regulators, and in both modes to supply power to the controller and auxiliary sensor. Accordingly, the controller and auxiliary sensor are continuously enabled whereas the PFC and DC-DC stages of the LED driver are disabled during standby modes. Additional circuitry may selectively disconnect voltage sensing resistance networks from the LED driver for further reductions in power consumption during standby mode.