Semiconductor Reverse Connection Protection Circuit
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Solution Overview
Problem
Existing semiconductor devices for load drive circuits with switching elements face issues when reverse-connected, including increased man-hours and costs due to the need for additional manufacturing steps, and potential operational problems like high impedance outputs and heat generation, especially when using depression type MOSFETs.
Innovation Solution
A semiconductor device design that includes a power chip with a switching element, a control chip with a control circuit and a reverse connection protection circuit, using protective resistors and a control voltage formation circuit to suppress current flow through the control chip during reverse connection, thereby preventing heat generation and ensuring reliable switching without requiring a depression type MOSFET.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a depression type MOSFET is used to suppress current flow during reverse connection, then current suppression is improved, but manufacturing complexity and cost increase due to additional manufacturing steps
Solution Approach 1:
The patent changes the electrical parameters of standard MOSFETs by configuring them in specific circuit arrangements (series/parallel combinations with controlled gates) rather than using specialized depression type MOSFETs. This achieves the required current suppression characteristics while maintaining compatibility with standard manufacturing processes.
Solution Approach 2:
The patent introduces intermediate control circuits that mediate between the power supply and the MOSFETs. These control circuits actively manage the switching states of standard MOSFETs to achieve the protective function previously requiring specialized depression type devices, thereby simplifying manufacturing.
2Reliability
If a depression type MOSFET is integrated into the control chip, then reverse connection protection is improved, but manufacturing cost increases due to additional manufacturing steps and yield drop
Solution Approach 1:
The patent makes standard MOSFETs perform multiple functions by using them both as normal switching elements and as protective elements during reverse connection. By controlling the gate states of these universal MOSFETs, the system achieves reverse connection protection without requiring separate specialized components, thereby reducing manufacturing costs and improving yield.
Solution Approach 2:
The patent merges the protective function with the normal switching function by using the same MOSFETs for both purposes. The control circuit integrates reverse connection detection and protection logic with the normal switching control, eliminating the need for separate depression type MOSFETs and reducing overall device complexity and manufacturing cost.
3Device complexity
If no reverse connection protection circuit is provided, then device complexity is reduced, but operational reliability deteriorates due to potential transistor malfunction and high impedance output
Solution Approach 1:
The patent implements preliminary protection actions by detecting reverse connection conditions early and immediately adjusting the gate states of MOSFETs to prevent harmful current flow. The control circuit is designed to automatically respond to reverse connection before damage can occur, ensuring operational reliability without requiring complex additional protection circuits.
4Reliability
If protective measures for reverse connection are added, then reliability during reverse connection is improved, but current flow through control chip increases causing heat generation
Solution Approach 1:
The patent implements periodic or conditional control of MOSFET gate states based on the detected power supply connection status. During normal operation, MOSFETs switch periodically to control load power. During reverse connection, the control circuit immediately changes the gate states to a protective configuration, minimizing current flow through the control chip and reducing heat generation while maintaining reliability.
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 design allows for reliable switching of the power chip to an on-state while suppressing heat generation and current flow through the control chip during reverse connection, reducing manufacturing complexity and costs, and ensuring problem-free operation even when the power supply is reverse-connected.
Implementation Method 1
the reverse connection protection circuit has protective resistors, interposed between the control circuit and the positive electrode side of the power supply
Implementation Method 2
a control voltage formation circuit into which is input an intermediate voltage of the protective resistors and which forms a control voltage that controls the switching element of the power chip into an on-state
Data Source
AI summary
The semiconductor device includes a power chip including a switching element that switches a supply of power from a power supply to a load between an on-state and an off-state, a control chip in which is incorporated a control circuit that controls the switching element of the power chip, and a reverse connection protection circuit, provided in the control chip, that controls the switching element of the power chip into an on-state when the power supply is reverse-connected, wherein the reverse connection protection circuit has protective resistors, interposed between the control circuit and the positive electrode side of the power supply, and a control voltage formation circuit into which is input an intermediate voltage of the protective resistors and which forms a control voltage that controls the switching element of the power chip into an on-state when the power supply is reverse-connected.