High-Voltage Protection Circuit for Low-Leakage Node Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Circuit components are vulnerable to damage from wide voltage swings, particularly in applications like the FlexRay automotive network communications protocol, where voltage fluctuations can exceed the safe operating range, and existing solutions like high voltage silicon-on-insulator (HV SOI) processes or high voltage isolation diodes are costly and complex.
Innovation Solution
The implementation of a high voltage detection circuit and control circuitry using unidirectional conduction devices and switches to manage current flow, preventing leakage and maintaining transistors within a safe operating area without requiring HV SOI processes, allowing for the use of more affordable BCD process technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high voltage silicon-on-insulator (HV SOI) processes or high voltage isolation diodes are used to protect circuit components from wide voltage swings, then component reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the voltage threshold parameter by using a voltage divider network (R1, R2) that scales down the high voltage signal to a level suitable for the detection circuit. This allows the use of standard low-voltage transistors instead of requiring specialized high voltage processes, thereby reducing device complexity while maintaining protection reliability
Solution Approach 2:
The patent introduces an intermediary detection circuit that acts as a mediator between the high voltage environment and the low voltage transistors. The detection circuit includes intermediate voltage nodes (node 202, node 106) that translate high voltage conditions into controllable signals for switching devices, avoiding direct exposure of sensitive components to high voltage stress
2Loss of energy
If high voltage silicon-on-insulator (HV SOI) processes are used to prevent leakage, then leakage current is reduced, but manufacturing cost increases
Solution Approach 1:
Instead of using expensive HV SOI processes to prevent leakage, the patent inverts the approach by using standard low-cost transistors with carefully designed gate control. The switching devices (MP3, MP4, MN1, MN2) are controlled to turn off completely under high voltage conditions, and the unidirectional conduction devices (D1, D2, D3) are positioned to block reverse leakage paths, achieving low leakage without expensive processes
Solution Approach 2:
The patent employs standard bipolar-CMOS-DMOS (BCD) process transistors that are cheaper and more readily available than HV SOI devices. These standard transistors are used in a configuration where they are protected from damage by the detection and control circuitry, allowing the use of inexpensive, easily manufacturable components instead of costly specialized devices
3Reliability
If switches are used to selectively couple nodes and control current flow, then component safety is improved, but device complexity increases
Solution Approach 1:
The patent segments the protection function into separate switching devices for different nodes (MP3 for node 101-102, MP4 for node 101-103, MN1 for node 104-ground, MN2 for node 105-ground). Each switch independently controls current flow at critical points, allowing modular protection that can be implemented with discrete devices rather than a single complex protection circuit
Solution Approach 2:
The patent combines the detection function and the switching control function into an integrated system. The detection circuit directly controls the gate voltages of the switching devices through interconnected nodes (node 202 connected to node 106, which controls MP3 and MN1). This merging eliminates the need for separate control logic and reduces overall device complexity despite using multiple switches
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
Effectively protects circuit components from damage due to wide voltage swings by controlling current flow and preventing leakage, ensuring safe operating conditions across a range of voltages without the need for expensive HV SOI processes, thus enhancing reliability and reducing manufacturing costs.
Implementation Method 1
a high voltage detection circuit coupled to node 101. The high voltage detection circuit is configured to generate a detection signal indicating whether a voltage at node 101 exceeds a predetermined threshold
Implementation Method 2
The first switch is for coupling node 101 to node 102 responsive to a first control signal having a first value, and for decoupling node 101 from node 102 responsive to the first control signal having a second value
Implementation Method 3
protection circuitry for disabling current flow in certain conditions. Various embodiments may be used with the FlexRay automotive network communications protocol... unidirectional conduction devices that block leakage currents
Implementation Method 4
If the voltage at node 101 exceeds the predetermined threshold, a closed one of the switches is opened, to disable the current flow across the load
Data Source
AI summary
An apparatus includes first and second switches. The first switch is for coupling a first node to a second node responsive to a first control signal having a first value, and for decoupling these nodes responsive to the first control signal having a second value. The second switch is for coupling the first node to a third node responsive to a second control signal having the first value, and for decoupling these nodes responsive to the second control signal having the second value. A load is coupled between the second and third nodes. A detection circuit coupled to the first node is configured to generate a signal indicating whether voltage at the first node exceeds a threshold. First and second modules are configured to set the first and second control signals to the second value responsive to the signal indicating that the voltage at the first node exceeds the threshold.