Semiconductor Regulator Integrating Soft Start and Current Limit
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Solution Overview
Problem
Conventional series regulators have large circuit scales and chip sizes due to separate soft start and current limit circuits, leading to increased costs and high power consumption during overcurrent protection, which can cause chip temperature issues.
Innovation Solution
A semiconductor integrated circuit that combines soft start and overcurrent protection functions into a single circuit, using a current detection circuit, feedback voltage generation, and a control circuit with comparator and buffer functions to manage output voltage and current, reducing chip size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate soft start circuit and current limit circuit are provided, then overcurrent protection function is achieved, but circuit scale and chip size increase
Solution Approach 1:
The patent combines the soft start circuit and current limit circuit into a single integrated circuit. The error amplifier serves dual functions: during startup it implements soft start by controlling the output voltage to rise gradually, and during normal operation it implements current limiting by comparing feedback voltage with reference voltage. This merging eliminates the need for separate circuits, reducing chip size while maintaining both protection functions.
Solution Approach 2:
The error amplifier is designed to perform multiple functions: it acts as a soft start controller during power-on by gradually increasing output voltage, and simultaneously serves as a current limit controller during operation by comparing feedback voltage with reference voltage. This multi-functionality allows a single circuit element to replace what would traditionally require separate dedicated circuits, thereby reducing overall circuit scale and chip area.
2Reliability
If conventional current limit circuit is used, then overcurrent protection is provided, but power consumption increases during overcurrent events
Solution Approach 1:
The patent employs feedback mechanisms where the feedback voltage (proportional to output voltage) is continuously compared with the reference voltage in the error amplifier. During overcurrent conditions, this feedback control dynamically adjusts the output voltage to maintain current within safe limits while minimizing power dissipation. The feedback loop ensures that the regulator responds optimally to load conditions, reducing unnecessary power consumption during overcurrent events compared to conventional circuits that may maintain higher voltage drops.
Data Source
AI summary
A regulator includes a transistor connected between an input and an output. A feedback voltage controls the transistor to keep the output voltage constant. A first circuit functions as a comparator to compare a detection voltage from the output of the transistor and the feedback voltage when the output current is higher than a predetermined value, and functions as a buffer when the output current is lower than the predetermined value. A second circuit receives a reference voltage, the feedback voltage, and an output from the first circuit, and generates (i) a difference between the feedback voltage and the first circuit output when the reference voltage is lower than the first circuit output, and (ii) a difference voltage between the feedback voltage and the reference voltage when the reference voltage is higher than the first circuit output, and supplies a control voltage to control the output of the transistor.