Power Supply Circuit Feedback Disconnection Protection
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Solution Overview
Problem
Power supply circuits for integrated circuits, such as DC-DC converters, face instability in output voltage when the feedback line is disconnected, potentially leading to load breakdown.
Innovation Solution
A power supply circuit comprising a driver, control circuit, and protection circuit, where the control circuit generates switching pulses for transistors to regulate output voltage, and the protection circuit outputs an interruption signal when the node voltage exceeds a reference voltage, preventing the transistors from conducting and thus stabilizing the output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feedback line is disconnected, then the output voltage becomes unstable and rises to harmful levels, but adding a protection circuit increases device complexity
Solution Approach 1:
The protection circuit proactively monitors the node voltage before the feedback disconnection causes harmful effects. By detecting voltage abnormalities in advance and preemptively turning off the transistors, the system prevents output voltage instability rather than reacting after the problem occurs.
Solution Approach 2:
The protection circuit acts as an intermediary monitoring layer between the driver circuit and the load. It observes the node voltage through the second low-pass filter and intervenes by generating interruption signals when abnormalities are detected, thus mediating between the power supply function and load protection requirements.
2Reliability
If the protection circuit continuously monitors node voltage, then load protection is improved, but energy consumption increases
Solution Approach 1:
The protection circuit employs periodic monitoring through the second low-pass filter circuit that processes node voltage at controlled intervals. The continuous monitoring is achieved through the natural filtering action of the RC circuit, which smooths voltage variations and enables the comparator to detect sustained abnormalities rather than transient spikes, reducing false alarms and unnecessary transistor switching.
Solution Approach 2:
The system changes the monitoring parameter from direct feedback voltage to node voltage through a separate low-pass filter. This parameter transformation allows the protection circuit to monitor power stage health independently of the feedback control loop, enabling protection functionality without interfering with the primary voltage regulation operation and minimizing additional energy consumption.
Data Source
AI summary
A power supply circuit according to an embodiment includes an driver, a control circuit, and a protection circuit. The driver includes a first transistor connected between a high-potential-side power supply and a node and a second transistor connected between a low-potential-side power supply and the node. The control circuit generates, according to an output voltage to a load connected to the node via a first low-pass filter circuit, first and second switching pulses for alternately switching the first and second transistors. The protection circuit outputs, when a voltage of the node via a second low-pass filter circuit exceeds a first reference voltage, an interruption signal for making at least the first transistor nonconductive.