Switching Regulator Startup Acceleration via Error Amplifier Reference Voltage
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Solution Overview
Problem
The startup time for switching regulators controlling LEDs is prolonged at lower requested outputs due to the delay in charging capacitors in the feedback circuit, which affects the generation of the error voltage needed to achieve the desired output.
Innovation Solution
Setting the reference voltage of the error amplifier to a higher voltage during startup, based on the maximum irradiance capability, forces faster charging of capacitors and reduces the delay in generating the error voltage, thereby accelerating the startup of the switching regulator. This approach is independent of the requested output, allowing the switching regulator to reach the desired output more quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the reference voltage is set lower for lower requested output, then the system operates efficiently at the requested output level, but the startup time increases due to slower capacitor charging
Solution Approach 1:
The patent applies preliminary action by setting the reference voltage to a higher initial value during the startup phase, before the system reaches its steady-state operation. This preliminary high voltage setting accelerates capacitor charging and error voltage generation at startup, reducing startup time. Once the system stabilizes, the reference voltage is adjusted to the appropriate lower value for efficient operation at the requested output level, thus resolving the contradiction between startup speed and operational efficiency
Solution Approach 2:
The patent implements dynamics by making the reference voltage time-dependent rather than static. During startup, the reference voltage is dynamically set to a higher value to accelerate system initialization. After startup completion, it transitions to a lower value matched to the requested output. This dynamic adjustment allows the system to optimize for both fast startup and efficient steady-state operation, resolving the contradiction between startup time and operational efficiency
2Speed
If the reference voltage is set to a higher voltage during startup, then the capacitor charging speed increases and startup time is reduced, but the operational reference voltage must be adjusted down for lower output requests
Solution Approach 1:
The patent uses preliminary action by implementing a startup detection mechanism that identifies when the system is in the startup phase. Upon detecting startup conditions, the control logic automatically sets the reference voltage to a higher preliminary value to accelerate capacitor charging. After detecting that startup is complete (when the error voltage reaches a threshold), it transitions to the normal operational reference voltage based on the requested output. This approach manages the added control complexity by using clear phase-based logic
Solution Approach 2:
The patent applies periodic action by dividing the system operation into distinct phases: startup phase and steady-state phase. During the startup phase, the reference voltage is periodically set to a higher value. Once the error voltage reaches a predetermined threshold indicating startup completion, the system transitions to the steady-state phase with the appropriate operational reference voltage. This phase-based periodic control manages complexity through clear temporal separation of different operating conditions
3Loss of time
If the reference voltage is set based on maximum irradiance capability during startup, then the startup time is reduced independent of requested output, but the reference voltage must be dynamically adjusted after startup based on actual output requirements
Solution Approach 1:
The patent applies preliminary action by setting the reference voltage to a maximum preliminary value during startup, independent of the final requested output level. This ensures maximum capacitor charging current and fastest possible startup. After startup completion (detected when error voltage reaches threshold), the reference voltage is then adjusted to the appropriate value based on the actual requested output. This two-stage approach prioritizes fast startup while maintaining operational accuracy
Solution Approach 2:
The patent implements dynamics by making the reference voltage adaptive across different operational phases. During startup, it uses a fixed high value for maximum speed. After startup, it dynamically adjusts to match the requested output level. This dynamic behavior resolves the contradiction by accepting temporary operational complexity during the transition phase in exchange for significantly reduced startup time, while maintaining simple operation during steady-state
Data Source
AI summary
A system and method for operating one or more light emitting devices is disclosed. In one example, a reference voltage input at an error amplifier receiving a feedback signal from the one or more light emitting devices is adjusted to a first higher voltage independent of a requested irradiance of the one or more light emitting devices during startup in order to accelerate startup of a switching regulator driving the one or more light emitting devices. Subsequently, upon an output of the switching regulator reaching a desired voltage, the reference voltage is adjusted based on the desired irradiance of the one or more light emitting devices.