Power Switch Short Circuit Protection via Transistor Coupling
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Solution Overview
Problem
Existing power switches, such as those in voltage regulators, face challenges in efficiently managing short circuit currents, which can damage the switch and power supply due to their high current capacity when in a state of lowest resistance.
Innovation Solution
Incorporating short circuit protection circuitry that rapidly interrupts current by directly coupling the control port with the first port of the power transistor in response to a drop in output voltage, using a short circuit control transistor and high pass filtering means to ensure activation only during a short circuit condition, thereby preventing damage from excessive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the bypass switch is in a state of lowest resistance to provide maximum current capability, then the reaction speed of the electronic circuit is improved, but the risk of damage from short circuit current increases
Solution Approach 1:
The protection circuit is activated in advance to detect voltage drops before they can cause damage. The circuit monitors the voltage across the bypass switch and preemptively triggers the protection mechanism when a short circuit condition is detected, preventing damage before it occurs.
Solution Approach 2:
A protection circuit is introduced as an intermediary between the bypass switch and the potential short circuit condition. This intermediary circuit includes a detection mechanism that senses voltage drops and a control mechanism that activates a protective element (such as a series switch or current limiting device) to interrupt or limit the short circuit current.
2Reliability
If short circuit protection circuitry is added to rapidly interrupt current, then the protection reliability is improved, but the device complexity increases
Solution Approach 1:
The protection circuit utilizes the inherent electrical characteristics of the bypass switch (voltage drop across it) as the trigger signal for protection activation. The system serves itself by using its own operational parameters to detect fault conditions and initiate protection, eliminating the need for external sensors or complex control systems.
Solution Approach 2:
The protection mechanism responds to changes in electrical parameters (voltage drop across the bypass switch) to detect short circuit conditions. By monitoring parameter changes rather than requiring complex fault detection logic, the circuit achieves reliable protection with minimal added 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
This solution effectively reduces current through the power transistor during a short circuit, protecting the power switch and supply voltage by rapidly interrupting the current and preventing damage from excessive flow.
Implementation Method 1
A state and/or the resistance (notably the drain-source resistance) of the short circuit control transistor may be controlled via the control port (e.g. the gate) of the short circuit control transistor, and a voltage level at the control port (e.g. the gate) of the short circuit control transistor may (e.g. only) depend on the output voltage
Data Source
AI summary
A power providing circuit which is configured to provide a current at an output voltage to a load at an output of the power providing circuit is described. The power providing circuit comprises a power transistor which is configured to draw the current from a supply voltage, wherein a resistance of the power transistor is controlled using a control voltage which is applied to a control port of the power transistor. Furthermore, the power providing circuit comprises short circuit protection circuitry which is configured to couple the control port of the power transistor with a first port of the power transistor to put the power transistor in an off-state, subject to a drop of the output voltage.