Parallel Protection Transistor Circuit for Overvoltage Pulse Diversion
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Solution Overview
Problem
Conventional overvoltage protection circuits in electronic devices are inefficient and space-consuming, particularly in compact designs, as they require high-input voltage dimensions and result in significant power loss and the need for large electrolytic capacitors, which are costly and impractical.
Innovation Solution
A circuit that incorporates a protection transistor connected in parallel to the overvoltage protection element, switching from blocking to conducting operation during overvoltage pulses, forming a second current path to balance and dissipate the remaining pulse, thus protecting downstream components without affecting normal operation or requiring high-capacity capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field effect transistor is used in series path to block overvoltage, then protection is provided, but voltage loss increases and power loss becomes very high
Solution Approach 1:
Instead of placing the field effect transistor in the series path (where it would block normal current and cause power loss), the invention places it in a parallel path. The transistor remains in blocking state during normal operation and only activates during overvoltage events, diverting excess current away from the load rather than blocking the main current path.
Solution Approach 2:
The field effect transistor acts as an intermediary element that provides an alternative current path during overvoltage conditions. By controlling the transistor's switching state through its gate terminal, the circuit can selectively activate the parallel protection path without affecting normal series current flow, thus avoiding continuous power loss.
2Reliability
If input voltage is dimensioned significantly higher than output voltage for transistor operation, then protection function is achieved, but voltage loss increases
Solution Approach 1:
The invention inverts the conventional approach by not requiring the input voltage to be dimensioned higher than output voltage. Instead, the parallel configuration with controlled switching allows the transistor to activate only when overvoltage occurs, eliminating the need for continuous voltage headroom and reducing voltage loss.
3Reliability
If electrolytic capacitor with sufficient capacity is used to filter overvoltage pulse, then filtering is improved, but installation space increases
Solution Approach 1:
The invention replaces the mechanical/electrical filtering approach (using large electrolytic capacitors) with an active electronic switching approach. The field effect transistor, controlled by a small capacitor and resistor network, dynamically switches to divert overvoltage pulses, achieving the same protection function without requiring large physical capacitor components.
Solution Approach 2:
The invention changes the operating parameters of the protection circuit by using a field effect transistor with very low on-resistance when activated. This allows efficient discharge of overvoltage pulses through the parallel path without requiring large energy storage capacitors, thus reducing component size and installation space.
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 provides effective overvoltage protection with low power loss and reduced component size, ensuring the protection of electronic components against high-energy interference while maintaining normal circuit functionality and minimizing space and cost requirements.
Implementation Method 1
an overvoltage protection element which is connected in parallel to the input side and is set up, when an overvoltage pulse occurs on the input side, at least part of the overvoltage pulse via a first current path derive
Implementation Method 2
A protection transistor is used in the circuit in addition to the overvoltage protection element. The protective transistor is connected in parallel to the output side of the circuit and switches from blocking operation to conducting operation when an overvoltage pulse occurs on the input side
Data Source
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AI summary
The invention relates to a circuit (S) for overvoltage protection. The circuit (S) comprises an input side (1) to which an input voltage (u1) can be applied, an output side (2) to which an output voltage (u2) can be tapped, and an overvoltage protection element (V4) which is connected in parallel to the input side (1) and is configured to divert at least part of an overvoltage pulse via a first current path (i1) when an overvoltage pulse occurs at the input side (1). According to the invention, a protection transistor (T1) is connected in parallel to the output side (2) and switches from blocking to conducting mode when an overvoltage pulse occurs at the input side (1). This creates a second current path (i2) parallel to the first current path (i1) along the protection transistor (T1), so that the remaining overvoltage pulse can be diverted via the second current path (i2).