Semiconductor Circuit Abnormal Voltage Detection and Switching
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Solution Overview
Problem
Semiconductor circuits with operational amplifiers face issues when external resistor elements disconnect, leading to excessive voltage application to external loads due to disconnection of the negative feedback circuit.
Innovation Solution
A semiconductor circuit design that includes an abnormality detecting circuit, a normal signal generating unit, and a switching circuit, which detects abnormal voltages and switches to output a normal voltage instead of the abnormal voltage, preventing excessive voltage application to external loads even when external resistor elements are disconnected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external resistor elements are used to adjust output voltage, then voltage adjustment flexibility is improved, but connection reliability deteriorates
Solution Approach 1:
The patent introduces an abnormality detecting circuit as an intermediary between the external resistor elements and the operational amplifier. This detector monitors the feedback voltage and identifies when external resistors are disconnected, preventing the operational amplifier from functioning as a comparator and generating excessive output voltage. The intermediary detects the abnormal connection state and enables protective action.
Solution Approach 2:
The patent implements a feedback mechanism where the abnormality detecting circuit continuously monitors the voltage at the inverting input terminal of the operational amplifier. When the external resistors are disconnected, the feedback voltage becomes abnormal (e.g., zero or exceeds reference voltage), and this abnormal feedback signal triggers the protective switching action to prevent excessive output voltage.
2Device complexity
If external resistor elements are disconnected, then device simplicity is improved, but output voltage stability deteriorates
Solution Approach 1:
The patent applies preliminary action by detecting the disconnection of external resistor elements before the operational amplifier can generate excessive output voltage. The abnormality detecting circuit proactively identifies the abnormal feedback voltage condition and triggers the switching circuit to connect the normal voltage generating unit in advance, preventing the harmful effect of excessive voltage before it occurs.
Solution Approach 2:
The patent provides beforehand cushioning by preparing a normal voltage generating unit that can immediately take over when external resistors are disconnected. This backup voltage generation path is ready in advance and is switched in when the abnormality detecting circuit identifies a disconnection, cushioning against the potential damage from excessive voltage to the external load.
3Stability of the object's composition
If abnormality detection and switching circuits are added, then output voltage stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the abnormality detection function and the protective switching function into an integrated protective circuit unit. The abnormality detecting circuit and switching circuit work together as a unified protective mechanism, reducing the need for separate independent components and minimizing the overall increase in device complexity while maintaining output voltage stability.
Data Source
AI summary
A semiconductor circuit (10a) comprises a first terminal section (17) to be connected to a connection point of two external resistors; a second terminal section (18) to be connected to an external circuit; a voltage circuit section having a first terminal connected to the second terminal section (18); a reference voltage circuit section (102) which outputs a predetermined voltage; an operational amplifier (104) having a first input terminal connected to the reference voltage circuit section (102), a second input terminal connected to the first terminal section (17), and an output terminal connected to a second terminal of the voltage circuit section; an abnormality detecting circuit which detects an abnormal voltage of the first terminal section (17); a normal signal generating unit (130) which generates a normal signal; and a switching circuit which, when the abnormality detecting circuit detects the abnormal voltage, does not output a voltage based on the first terminal section (17) to the second terminal section (18) and instead outputs a normal voltage based on the normal signal to the second terminal section (18).