Low Dropout Regulator Switching for Low-Supply Voltage Accuracy
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Solution Overview
Problem
Low dropout regulators face challenges in maintaining output voltage accuracy when the supply voltage is close to the target value, leading to larger errors and reduced driving current, especially when the supply voltage drops below a certain threshold.
Innovation Solution
A low dropout regulator design incorporating an amplifier, a transistor, and a selector, where the selector chooses a first path to transmit a specific voltage to the transistor when the supply voltage is below a threshold, ensuring the transistor is fully conducted and the output voltage equals the supply voltage, thereby maintaining voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the supply voltage value is reduced to achieve lower power consumption, then power consumption is reduced, but the output voltage accuracy deteriorates and driving current decreases
Solution Approach 1:
The patent changes the control voltage parameter applied to the pass transistor based on the supply voltage level. When supply voltage is high, a standard control voltage is used for normal LDO regulation. When supply voltage drops below a threshold, the control voltage is adjusted to a different level to maintain transistor conduction and ensure output voltage accuracy is maintained despite the lower supply voltage
Solution Approach 2:
The patent implements dynamic switching between different control modes based on supply voltage conditions. A voltage detection circuit continuously monitors the supply voltage and dynamically switches the control strategy: using conventional LDO control when supply voltage is sufficient, and transitioning to an alternative control path when supply voltage falls below the threshold, thereby adapting to changing operating conditions
2Temperature
If the supply voltage value is reduced to achieve lower operating voltage, then operating voltage is reduced, but the transistor conduction becomes insufficient and output voltage cannot be maintained
Solution Approach 1:
The patent modifies the control voltage parameter applied to the pass transistor based on supply voltage conditions. When supply voltage is high, standard LDO control is used. When supply voltage drops below a threshold, the control voltage is changed to a level that ensures sufficient transistor conduction, maintaining output voltage stability despite the lower supply voltage headroom
Solution Approach 2:
The patent introduces a voltage detection circuit and control logic as intermediaries between the supply voltage source and the pass transistor. This intermediary system monitors supply voltage levels and actively adjusts the control signal to the pass transistor, ensuring reliable conduction and output voltage maintenance across varying supply conditions
Data Source
AI summary
A low dropout regulator is disclosed. The low dropout regulator includes an amplifier, a transistor, and a selector. The transistor is coupled to the amplifier. The selector is coupled to the amplifier and the transistor. When a supply voltage value of the transistor is less than a supply voltage threshold value, a first path of the selector is selected and a first selector voltage value is transmitted by the selector to the transistor so as to fully conduct the transistor, and an output voltage value of the transistor is equal to the supply voltage value.