Line Transient Management in LDO Voltage Regulators
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Solution Overview
Problem
Existing voltage regulators lack effective line transient management, leading to output voltage transients and potential circuit resets due to sudden changes in input voltage, and existing aid transistors are not process, voltage, and temperature-independent, causing unnecessary activation during normal operations and affecting voltage regulation.
Innovation Solution
A control circuit for an aid transistor in a low-dropout voltage regulator that converts output voltage to a secondary voltage using a low-pass filter, ensuring the aid transistor turns ON only during transients and remains OFF during stable conditions, independent of process, voltage, and temperature variations, thereby assisting the pass element without interfering with the main voltage regulation loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the aid transistor is activated during line transients, then the output voltage stability is improved, but the activation may occur during normal operations due to process, voltage and temperature variations
Solution Approach 1:
The control circuit serves as a mediator that filters and conditions the output voltage signal before applying it to the aid transistor gate. By introducing this intermediate processing stage, the system achieves immunity to process, voltage and temperature variations that would otherwise cause spurious activation, while maintaining stable output during genuine line transients
Solution Approach 2:
The control circuit transforms the output voltage parameter into a gate control voltage parameter with different characteristics. This parameter transformation ensures that only significant output voltage changes (line transients) trigger aid transistor activation, while normal variations due to process, voltage and temperature changes are filtered out
2Measurement precision
If a control circuit is added to manage the aid transistor, then the precision of transient response is improved, but the complexity of the voltage regulator increases
Solution Approach 1:
The control circuit is designed to perform multiple functions: it monitors output voltage, detects line transient conditions, generates appropriate gate control signals, and maintains compatibility with the existing voltage regulation loop. This multi-functionality achieves precise transient response management without requiring separate dedicated circuits for each function, thereby limiting the increase in overall system complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively manages line transients by ensuring the aid transistor only activates during necessary conditions, maintaining stable output voltage and preventing unnecessary activation, thus enhancing the stability and accuracy of voltage regulation across varying conditions.
Implementation Method 1
a low pass filter coupled to receive the gate control voltage and to provide a filtered gate control voltage to the gate of the aid transistor
Data Source
AI summary
A voltage regulator and a gate control circuit for an aid transistor coupled to assist a pass element for the voltage regulator during line transients having a given slope are disclosed. The gate control circuit includes a first circuit coupled to receive an output voltage of the voltage regulator on a first node and to provide a gate control voltage that mirrors the output voltage on a second node. A low pass filter is coupled to receive the gate control voltage and to provide a filtered gate control voltage to the gate of the aid transistor.