LDO Startup Mode Control for Reliable Logic Power-Up
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Low drop-out (LDO) regulators face challenges in ensuring reliable operation during start-up, as the output voltage may initially be below the minimum acceptable operating voltage for digital logic controllers, leading to unreliable control signaling and potential suboptimal or non-operation of the digital logic controller.
Innovation Solution
Incorporating LDO start-up circuitry that defaults the LDO regulator to a predetermined mode during start-up, preventing the digital logic controller from controlling the mode until the output voltage reaches a sufficient threshold, and using a level shifter to adjust voltage levels for reliable signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the LDO regulator is controlled by digital logic controller during start-up, then the mode can be dynamically adjusted, but the output voltage may be below the minimum acceptable operating voltage leading to unreliable control signaling
Solution Approach 1:
The start-up circuitry forces the LDO regulator into a predetermined mode (first mode) during the start-up period before the digital logic controller is fully operational. This preliminary action ensures that the regulator provides sufficient output voltage to power the digital logic controller reliably, avoiding the reliability issue of unstable control signaling while maintaining the ability to switch modes later when the controller is ready.
2Device complexity
If the digital logic controller receives power from the LDO regulator output, then the system is simplified, but the controller cannot operate when output voltage is below its minimum acceptable operating voltage
Solution Approach 1:
During start-up, the start-up circuitry ensures the LDO regulator operates in a predetermined mode that guarantees sufficient output voltage to power the digital logic controller. This preliminary configuration allows the simplified power supply architecture to function correctly by ensuring the controller receives adequate power before it attempts to operate or send control signals.
Solution Approach 2:
The start-up circuitry monitors the output voltage of the LDO regulator and uses this feedback to determine when the digital logic controller has received sufficient power to operate reliably. Once the output voltage exceeds a threshold indicating the controller is ready, the start-up circuitry releases control, allowing the controller to take over mode selection.
3Speed
If the LDO regulator allows immediate mode switching upon power-up, then the system responds quickly to control signals, but the output voltage may not be stable causing suboptimal or non-operation
Solution Approach 1:
The start-up circuitry implements a predetermined sequence where the LDO regulator is first forced into a stable predetermined mode during start-up, allowing the output voltage to stabilize. Only after this preliminary stabilization phase does the circuitry allow mode switching based on digital logic controller commands, ensuring the system responds quickly only when voltage stability is guaranteed.
Data Source
Figure 1~2
Figure 3~4
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.