Semiconductor Device Voltage Dividing Circuit for Transistor Protection
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Solution Overview
Problem
Existing semiconductor devices for high current switching in automobiles face issues with transistor short-circuiting due to voltage supply failures, leading to inefficient power usage and instability caused by noise influences, especially when the control voltage supply malfunctions.
Innovation Solution
A semiconductor device with a voltage dividing circuit and a zener-diode configuration that ensures the source voltage remains higher than the gate voltage, even during abnormal conditions, using a low-voltage power supply to generate and regulate voltages for transistors, preventing transistor turn-on by noise and thus avoiding power supply shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control power supply is shut down or malfunctions, then the gate voltage and source voltage become equal to or close to 0 V, but the transistor turns on due to noise influence causing power supply shorting
Solution Approach 1:
The voltage dividing circuit is pre-configured to automatically generate a positive voltage at the source terminal when the control power supply fails, before noise can cause unwanted transistor activation. This preliminary voltage establishment prevents the harmful condition of Vgs becoming positive during failures.
Solution Approach 2:
The voltage dividing circuit acts as an intermediary mechanism between the control power supply and the transistor source terminal. It provides a buffer function that ensures the source voltage remains appropriately higher than gate voltage even when control power is lost, preventing direct noise-induced shorting.
2Reliability
If a gate-off power supply is produced by reducing the voltage of the main power supply, then the apparatus becomes complicated and energy loss increases
Solution Approach 1:
The voltage dividing circuit uses the existing low-voltage power supply to automatically generate the necessary source voltage through passive resistor division. No active gate-off power supply circuit is needed, as the system self-regulates the voltage relationship between source and gate terminals using simple passive components.
Solution Approach 2:
The invention extracts the essential function of maintaining source-gate voltage relationship from the complex gate-off power supply circuit. By removing the need for active voltage regulation and using only passive voltage division, the circuit complexity is dramatically reduced while maintaining the same protective function.
3Reliability
If the main power supply voltage is used for gate-off control, then voltage surge during operation causes the gate-off power supply to become unstable
Solution Approach 1:
The invention extracts the gate-off control function from the unstable main power supply voltage. By using a separate, stable low-voltage power supply for the voltage dividing circuit, the system eliminates the vulnerability to voltage surges and noise that affect main power supply-based gate-off circuits.
Solution Approach 2:
The voltage dividing circuit serves as a stable intermediary that decouples the gate-off control function from the noisy main power supply. It uses the clean, regulated low-voltage power supply to generate stable source voltage, acting as a buffer against voltage surges and electrical noise from the main power system.
Data Source
AI summary
A semiconductor device of the present invention includes a transistor having a drain and a source, a voltage being applied between the drain and the source from a high-voltage power supply, a drive device that generates a source voltage and a gate voltage for the transistor from a voltage of a low-voltage power supply lower than that of the high-voltage power supply, and a voltage dividing circuit connected to the low-voltage power supply, wherein when the source voltage is lower than a certain value, an output voltage from the voltage dividing circuit is applied to the source.