Low Dropout Regulator Capacitor Switching for Standby Loop Stability
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Solution Overview
Problem
Conventional low dropout regulators (LDOs) face challenges in maintaining loop stability during standby states, which affects their overall performance.
Innovation Solution
The proposed low dropout regulator incorporates a control unit connected to a second capacitor, allowing it to disconnect the first electrode plate of the second capacitor from the power transistor during standby, ensuring high loop stability by separating primary and secondary poles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second capacitor is always connected to the power transistor, then the LDO can maintain proper voltage regulation, but the loop stability deteriorates in standby state due to pole interaction
Solution Approach 1:
The patent applies the dynamics principle by making the connection between the second capacitor and the power transistor switchable rather than fixed. The control unit dynamically adjusts the connection state based on the LDO's operating condition (standby vs. normal operation), allowing the circuit to adapt its configuration for optimal performance in each state.
Solution Approach 2:
The patent segments the capacitor connection into two distinct states: connected and disconnected. By dividing the operation into these separate states controlled by the control unit, the system can optimize for loop stability during standby by disconnecting the capacitor, while maintaining voltage regulation capability during normal operation when connected.
2Reliability
If the second capacitor is disconnected during standby, then loop stability improves, but voltage regulation capability may be compromised
Solution Approach 1:
The control unit dynamically switches the capacitor connection based on operational requirements. During standby, the capacitor is disconnected to improve loop stability. During normal operation, the capacitor is connected to maintain proper voltage regulation, thus dynamically adapting to different power states.
Solution Approach 2:
The system periodically transitions between capacitor connected and disconnected states according to the operational mode. The control unit monitors the operating state and periodically adjusts the capacitor connection accordingly, ensuring optimal performance for each phase of operation.
Data Source
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AI summary
Provided are a low dropout regulator and an electronic device. The low dropout regulator comprises a control unit electrically connected to a second capacitor, the control unit being used for controlling the connection or disconnection between a first electrode plate of the second capacitor and a second end of a power tube. Therefore, when the low dropout regulator is in a standby state, the control unit controls the disconnection between the first electrode plate of the second capacitor and the second end of the power tube, such that the second end of the power tube has a relatively small connection capacitance, so as to ensure the separation of a dominant pole point at a control end of the power tube from a secondary pole point at the second end of the power tube, and thus, the low dropout regulator has a high loop stability when same is in the standby state, thereby improving the performance of the low dropout regulator.