LDO Regulator Overvoltage Protection Circuit
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Solution Overview
Problem
Low dropout regulators (LDO) in electronic power supplies, particularly in automobile electronics, face challenges in preventing output overvoltage due to rapid changes in load requirements, which can cause permanent damage to circuits.
Innovation Solution
A regulator design incorporating a driving circuit, an amplifying circuit, and an overvoltage protection circuit that detects increased voltage levels and conducts a larger current from the output terminal to ground to reduce excess energy, thereby preventing overvoltage phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the LDO circuit operates with rapid load changes to meet dynamic power requirements, then the adaptability and responsiveness are improved, but output overvoltage occurs causing circuit damage
Solution Approach 1:
The overvoltage protection circuit proactively detects voltage increases before they cause damage and preemptively activates the discharge transistor to release excess energy, preventing the harmful overvoltage condition from developing further
Solution Approach 2:
The discharge transistor acts as an intermediary component that provides a controlled path for excess energy to flow from the output terminal to ground, mediating between the power supply and load to prevent direct damage from overvoltage
2Reliability
If the LDO circuit uses a protection mechanism to prevent overvoltage, then circuit reliability is improved, but the device complexity increases
Solution Approach 1:
The discharge transistor serves multiple functions: it acts as a normal operating component for load regulation and simultaneously provides overvoltage protection, eliminating the need for separate protection circuitry and reducing overall system complexity
Solution Approach 2:
The overvoltage protection function is merged with the existing LDO control architecture by integrating the discharge transistor into the feedback loop, combining protection capabilities with the regulation mechanism in a unified circuit design
Data Source
AI summary
A regulator includes a driving circuit, an amplifying circuit and an overvoltage protection circuit. The driving circuit is configured to receive an input voltage and provide an output voltage through an output terminal. The amplifying circuit is configured to control the driving circuit according to the output voltage. The overvoltage protection circuit is configured to conduct a first current from the output terminal of the overprotection circuit to a ground terminal. When the overvoltage protection circuit detects that a voltage level of a node coupled to the driving circuit is increased, the overvoltage protection circuit conducts a second current from the output terminal of the overprotection circuit to the ground terminal to lower the output voltage, in which the second current is larger than the first current.