Switch Circuit Sub Transistor Voltage Control
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Solution Overview
Problem
The existing switch circuits using bipolar transistors generate excessive heat when turned off due to high resistance and power consumption, risking transistor malfunction.
Innovation Solution
A switch circuit design incorporating a first main transistor, a sub transistor, and a surge protection device, where the sub transistor is turned on when the main transistor is off to maintain a lower voltage, reducing heat generation by managing the voltage across the transistor circuit and using surge protection devices to control current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the main transistor is turned off to stop current flow, then power consumption is reduced, but voltage spikes occur causing heat generation and potential malfunction
Solution Approach 1:
A surge protection device is introduced as an intermediary component connected in parallel with the transistor circuit. When the main transistor turns off and voltage spikes occur, the surge protection device absorbs the excess voltage, preventing heat generation and damage to the transistor while allowing the transistor to remain in the off state with low power consumption.
Solution Approach 2:
The surge protection device is pre-configured in the circuit to cushion against voltage spikes before they can damage the transistor. By having this protective mechanism in place beforehand, the system can safely switch the transistor off for low power consumption without risking heat generation from uncontrolled voltage spikes.
2Use of energy by moving object
If the transistor resistance is increased when off to reduce current leakage, then power consumption decreases, but voltage stability deteriorates causing potential malfunction
Solution Approach 1:
The surge protection device acts as an intermediary that stabilizes voltage in the circuit. When the transistor is off with high resistance, the surge protection device maintains voltage stability by providing a controlled path for any voltage fluctuations, preventing malfunction while allowing the transistor to maintain low power consumption through high off-state resistance.
Data Source
AI summary
In a switch circuit for use in a vehicle, conduction between a drain electrode and a gate electrode of each of a first main transistor and a second main transistor is switched on or off depending on a voltage between the gate electrode and a source electrode. A first surge protection device is connected between the drain electrodes of the first main transistor and the second main transistor. The first surge protection device keeps a voltage that is applied to the first surge protection device at a first predetermined voltage or lower. A sub transistor is provided between the gate electrodes and the source electrodes of the first main transistor and the second main transistor. The sub transistor is turned on when the first main transistor and the second main transistor are turned off.