Power Regulator Open Detection Circuit for Feedback Terminal Protection
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Solution Overview
Problem
Conventional power regulators fail to completely shut off output when the feedback terminal becomes open due to errors in mounting or accidental disconnections, leading to unstable output voltages and potential damage to connected loads, and existing solutions are limited to specific types of regulators and do not apply to both linear and switching power supplies.
Innovation Solution
A power regulator design that includes an open detection circuit to detect an open feedback terminal and adjust the reference voltage to keep the transistor in an OFF state, ensuring the output voltage is nearly completely shut off, applicable to both linear and switching regulators regardless of their type or configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the feedback terminal is left open due to mounting errors or disconnections, then the circuit simplicity is maintained, but the output voltage becomes unstable and may damage connected loads
Solution Approach 1:
The open detection circuit proactively monitors the feedback terminal connection status before abnormal voltage can damage the load. When an open circuit is detected, the system preemptively adjusts the reference voltage to shut off the output transistor, preventing potential damage before it occurs.
Solution Approach 2:
The open detection circuit acts as an intermediary between the feedback terminal and the control circuit. It monitors the feedback voltage and, upon detecting an open circuit condition, mediates by adjusting the reference voltage to appropriately control the output transistor, ensuring safe operation.
2Device complexity
If conventional power regulators are used without open detection, then the device complexity is low, but they cannot completely shut off output when feedback terminal is open, leading to potential load damage
Solution Approach 1:
The open detection circuit continuously monitors the feedback terminal voltage and uses this feedback information to determine connection status. When the feedback voltage indicates an open circuit (exceeding a threshold), the system responds by adjusting the reference voltage to shut off the output, creating a closed-loop protection mechanism.
Solution Approach 2:
The circuit converts the potentially harmful open circuit condition into a detectable signal. By monitoring the feedback voltage, the system identifies the open circuit state and transforms this fault condition into a trigger for protective action, shutting off the output to prevent load damage.
3Reliability
If existing open detection solutions are applied, then feedback terminal protection is improved, but they are limited to specific regulator types and do not apply to both linear and switching power supplies
Solution Approach 1:
The open detection circuit is designed with universal applicability to both linear and switching power regulator types. By monitoring the feedback terminal voltage and comparing it against a threshold, the circuit can detect open conditions regardless of the specific regulator topology, making the protection mechanism broadly applicable across different power supply architectures.
Data Source
AI summary
A power regulator has an input terminal to receive an input voltage, an output terminal to output an output voltage, a transistor connected to the input and terminals, a feedback terminal to receive a feedback voltage, and a control circuit to control the transistor based on the feedback voltage at the feedback terminal and a reference voltage so as to keep the output voltage constant. Various implementations include an open detection circuit to detect an open state of the feedback terminal and, on detecting the open state, to vary the reference voltage and thereby keep the transistor in an OFF state, or a voltage holding circuit configured to hold the output voltage constant at a second voltage lower than the first voltage when the feedback terminal is in an open state.