Power Transistor Clamp Control for Noise-Immune Semiconductor Circuits
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Solution Overview
Problem
Existing semiconductor devices with high-voltage transistors face challenges in noise immunity and cost due to the need for larger transistors and external protection devices to manage induced current noise, leading to increased costs and potential breakdowns.
Innovation Solution
A semiconductor device with a power transistor, a clamp circuit, a resistive element, and a monitoring section that dynamically adjusts the clamp voltage based on the gate voltage, allowing for increased current absorption without enlarging the transistor or external protection devices, thereby enhancing noise immunity while controlling costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transistor size of the power transistor is increased to increase the current absorption capacity during active clamp operation, then the noise immunity is improved, but the chip cost increases
Solution Approach 1:
The clamp voltage is made dynamically adjustable based on the gate voltage level. When the gate voltage exceeds a predetermined threshold, the clamp voltage is increased to enhance current absorption capacity. This dynamic adjustment allows the system to optimize noise immunity only when needed, avoiding the need for a permanently larger transistor that would increase chip cost.
Solution Approach 2:
The invention changes the clamp voltage parameter in response to gate voltage conditions. By monitoring the gate voltage and adjusting the clamp voltage accordingly, the system optimizes the current absorption capacity of the power transistor during active clamp operation, improving noise immunity without requiring a larger transistor size.
2Reliability
If the size of external protection devices is increased to enhance noise immunity, then the current absorption capacity is improved, but the device complexity and cost increase
Solution Approach 1:
The power transistor is made to serve dual functions: its primary switching function and its current absorption function during active clamp operation. By utilizing the power transistor's own current absorption capacity enhanced by dynamic clamp voltage adjustment, the invention eliminates or reduces the need for separate external protection devices, thereby simplifying the overall device structure and reducing cost.
Solution Approach 2:
The power transistor is designed to perform multiple functions: normal switching operation and active clamp operation for current absorption. The dynamic clamp voltage adjustment mechanism enables the power transistor to effectively absorb current during noise events, making it a multi-functional component that reduces reliance on additional dedicated protection devices.
3Reliability
If the clamp voltage is increased to increase current absorption capacity, then the noise immunity is improved, but the voltage range for active clamp operation is reduced
Solution Approach 1:
The clamp voltage is dynamically adjusted based on the gate voltage level rather than being fixed. When the gate voltage is low, the clamp voltage is kept lower to maintain a wide operating range. When the gate voltage exceeds a predetermined value, the clamp voltage is increased to enhance current absorption capacity. This dynamic adjustment optimizes both the voltage range and current absorption capacity.
Solution Approach 2:
The invention changes the clamp voltage parameter in response to gate voltage conditions. By monitoring the gate voltage and adjusting the clamp voltage accordingly, the system optimizes the current absorption capacity of the power transistor during active clamp operation, improving noise immunity without requiring a larger transistor size.
Data Source
AI summary
The semiconductor device includes a power transistor that is disposed between a first signal line, which is coupled to a first external terminal, and a second signal line, which is coupled to a second external terminal. A gate electrode of the power transistor is coupled to a third signal line. The semiconductor device further includes a clamp circuit that clamps a voltage between the first signal line and the third signal line, a first resistive element that is disposed between the third signal line and the second signal line, and a monitoring section that monitors a voltage between the third signal line and the second signal line. The clamp circuit is configured so that a clamp voltage can be changed. The monitoring section exercises control to decrease the clamp voltage when the voltage between the third signal line and the second signal line exceeds a predefined threshold value.