Low Dropout Regulator Switching Control for Voltage Stability
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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 large output voltage drops and long response times due to difficulties in controlling the pass transistor's conductivity.
Innovation Solution
A low dropout regulator design incorporating an amplifier, a first transistor, a second transistor, and a switch that selects different paths based on a supply voltage threshold, fully conducting the first transistor when the supply voltage is below the threshold and adjusting the output voltage using the second transistor and amplifier when it exceeds the threshold, thereby minimizing output voltage drops during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the supply voltage value is close to the target LDO output voltage value, then the LDO operates in low dropout mode, but it becomes difficult to maintain the target LDO output voltage value
Solution Approach 1:
The patent changes the control parameter by using a supply voltage threshold to determine the operating mode. When the supply voltage is below the threshold, the LDO operates in one mode; when above, it operates in another mode. This parameter-based switching resolves the control difficulty in maintaining output voltage stability when the supply voltage is close to the target value.
Solution Approach 2:
The patent implements dynamic switching between two different control paths based on the supply voltage level. The first control path is used when supply voltage is below the threshold, and the second control path is used when supply voltage is above the threshold. This dynamic adaptation allows the system to maintain optimal performance across different operating conditions.
2Adaptability or versatility
If an analog switch is used to control the voltage value input to the gate terminal of the pass transistor, then the output voltage value can be adjusted, but a large output voltage drop is induced when there is a switching at the control signal
Solution Approach 1:
The patent prepares two different control paths in advance, each optimized for specific supply voltage conditions. By pre-configuring the first control path for low supply voltage operation and the second control path for high supply voltage operation, the system可以避免large output voltage drops during switching. The switch selectively activates the appropriate pre-prepared path based on the supply voltage threshold.
3Use of energy by moving object
If the supply voltage value is lower than the default value, then the LDO operates with limited headroom, but larger error of LDO output voltage value and smaller driving current are induced
Solution Approach 1:
The patent changes the control strategy based on the supply voltage parameter. When the supply voltage is below the threshold, the first control path is used which is optimized for low-voltage operation. When the supply voltage is above the threshold, the second control path is used which provides better voltage accuracy. This parameter-based control switching resolves the contradiction between power efficiency and output voltage accuracy.
Data Source
AI summary
A low dropout regulator is disclosed. The low dropout regulator includes an amplifier, a first transistor, a second transistor and a switch. When a supply voltage value of the low dropout regulator is less than a supply voltage threshold value, a first path of the switch is selected and a first switch voltage value is transmitted to the first transistor so as to fully conduct the first transistor, and an output voltage value of the low dropout regulator is equal to the supply voltage value. When the supply voltage value is not less than the supply voltage threshold value, a second path of the switch is selected and a second switch voltage value is transmitted to the first transistor so as to turn off the first transistor, and the output voltage value is adjusted by the second transistor and the amplifier.