LDO Startup Circuitry for Stable Digital Logic Power-Up
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Solution Overview
Problem
Low drop-out (LDO) regulators face challenges in ensuring reliable operation during start-up, as they may not provide a sufficient output voltage to digital logic controllers, leading to unreliable or suboptimal operation, and existing solutions complicate circuit design with additional power sources or components.
Innovation Solution
Incorporating LDO start-up circuitry that defaults the LDO regulator to a predetermined mode during start-up, preventing digital logic controller intervention, and using a level shifter to manage control signaling based on output voltage thresholds, ensuring the LDO regulator provides a minimum acceptable voltage to the digital logic controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the LDO regulator allows digital logic controller to control the mode during start-up, then the digital logic controller can optimize performance, but the output voltage may be insufficient leading to unreliable operation
Solution Approach 1:
The LDO start-up circuitry is configured to automatically default the LDO regulator to a predetermined mode during start-up before the digital logic controller is fully operational. This preliminary action ensures the output voltage is sufficient for reliable operation of the digital logic controller during its initialization phase, preventing control issues that would arise if the controller attempted to manage modes before being fully powered and stable.
2Reliability
If additional power sources are added to ensure sufficient voltage during start-up, then reliable operation is achieved, but circuit design complexity increases
Solution Approach 1:
The LDO start-up circuitry is integrated within the LDO regulator itself and automatically detects when the device is in start-up mode, then self-configures to default to a predetermined mode that ensures sufficient output voltage. This self-service mechanism eliminates the need for external additional power sources or complex startup circuits, maintaining reliability while minimizing added complexity.
Solution Approach 2:
The LDO start-up circuitry serves multiple functions: it detects start-up conditions, automatically selects appropriate operating modes, and ensures sufficient output voltage during initialization. By integrating these multiple functions into a single circuit block, the design achieves reliable start-up operation without requiring separate dedicated circuits for each function, thereby reducing overall system complexity.
Data Source
AI summary
A system comprising: a LDO regulator configured to receive a supply voltage and provide an output voltage based on a function of the supply voltage, the LDO regulator switchable between at least a first and second mode, wherein the first and second modes each define the output voltage provided to the output terminal based on different functions of the supply voltage; and a digital logic controller configured to select the mode of the LDO regulator by control signalling to the LDO regulator, the digital logic controller configured to receive power for the provision of the control signalling from the LDO regulator; wherein the LDO regulator comprises LDO start-up circuitry configured to cause the LDO regulator, during start-up, to default to a predetermined one of the first and second mode and the LDO start-up circuitry further configured to prevent the digital logic controller from controlling the mode of the LDO regulator.