Voltage Regulator Output Gating During Op-Amp Startup
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Solution Overview
Problem
Conventional voltage regulators have a long start-up time and increased semiconductor device size due to the need for a power source voltage-monitoring circuit, which delays their operation until the power source voltage is sufficient, and they struggle to control output voltage when the input voltage is lower than the operating range.
Innovation Solution
A voltage regulator design that includes a detecting circuit to monitor the operational amplifier's state, preventing the output transistor from conducting when the operational amplifier is not within its operating voltage range, thus preventing unintended high voltages from reaching the load circuit, and allowing quick start-up without monitoring the power source voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a power source voltage-monitoring circuit is included to ensure safe operation, then the load circuit is protected from high voltages, but the start-up time increases and the semiconductor device size increases
Solution Approach 1:
The patent extracts the voltage monitoring function from a separate power source voltage-monitoring circuit and integrates it into the operational amplifier itself. The operational amplifier's internal circuitry is designed to detect when the power source voltage reaches its operating range, eliminating the need for an external monitoring circuit while maintaining protection functionality.
Solution Approach 2:
The operational amplifier is designed to perform multiple functions: voltage comparison for regulation and power source voltage monitoring for startup detection. By making the operational amplifier multi-functional, the patent reduces the overall circuit complexity and eliminates dedicated monitoring components that would increase device size and startup time.
2Reliability
If a power source voltage-monitoring circuit is included to ensure safe operation, then the load circuit is protected from high voltages, but the semiconductor device size increases
Solution Approach 1:
The patent extracts the voltage monitoring function from a separate power source voltage-monitoring circuit and integrates it into the operational amplifier itself. The operational amplifier's internal circuitry is designed to detect when the power source voltage reaches its operating range, eliminating the need for an external monitoring circuit while maintaining protection functionality.
Solution Approach 2:
The patent merges the power source voltage monitoring function with the operational amplifier circuit. By combining these functions into a single integrated circuit block, the patent reduces the overall semiconductor device area while maintaining all necessary protection and regulation capabilities.
3Reliability
If the voltage regulator waits for sufficient power source voltage before operation, then the operational amplifier operates within its voltage range, but the start-up time becomes relatively long
Solution Approach 1:
The patent implements preliminary action by having the operational amplifier's internal circuitry continuously monitor the power source voltage and prepare for operation in advance. When the voltage reaches the sufficient level, the operational amplifier is already ready to immediately begin regulation, eliminating delays associated with external monitoring and control circuits.
Data Source
AI summary
A voltage regulator includes an operational amplifier that compares a feedback voltage that is proportional to an output voltage and a predetermined reference voltage that corresponds to a desired output voltage. The operational amplifier controls the conduction state of an output transistor according to the comparison. A detecting circuit monitors the operating state of the operational amplifier, and in the case that the operational amplifier is not operating, outputs a signal which causes the output transistor to be placed in a non-conductive state.