CMOS CAN Bus Driver Using Voltage Divider for High-Voltage Tolerance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional low-voltage CMOS processes are unable to handle the high voltage ranges required for CAN bus communication, and existing high-voltage CMOS processes are not radiation tolerant, making it challenging to implement radiation-hard driver circuits for bi-directional communication buses like CAN.
Innovation Solution
A bi-state driver circuit is designed with a voltage divider circuit and multiple strings of transistors to manage voltage levels effectively, allowing for reliable switching and high-voltage resilience in a low-voltage CMOS process, and a tri-state driver circuit is achieved by combining two bi-state driver circuits in inverse relationship.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-voltage CMOS process is used, then radiation tolerance is improved, but voltage handling capability deteriorates
Solution Approach 1:
The patent introduces a voltage divider circuit as an intermediary between the high-voltage bus line and the low-voltage CMOS transistors. This voltage divider steps down the high bus voltages to safe levels for the low-voltage transistors, enabling the use of radiation-tolerant low-voltage CMOS technology while maintaining compatibility with high-voltage CAN bus standards.
Solution Approach 2:
The patent transforms the voltage parameter by using a voltage divider circuit to convert high-voltage bus signals into low-voltage signals suitable for low-voltage CMOS transistors. This parameter transformation allows the transistors to operate within their safe voltage ranges while still interfacing with high-voltage communication buses.
2Object-affected harmful factors
If high-voltage CMOS process is used, then voltage handling capability is improved, but radiation tolerance deteriorates
Solution Approach 1:
The voltage divider circuit serves as a mediator that allows high-voltage CMOS transistors to interface with high-voltage bus lines while being protected from excessive voltages. Simultaneously, this configuration enables the use of radiation-tolerant transistor designs that can operate in high-voltage environments without requiring specialized high-voltage CMOS processes.
3Adaptability or versatility
If conventional CAN driver structure is used, then voltage range accommodation is improved, but radiation tolerance deteriorates
Solution Approach 1:
The patent segments the driver circuit into multiple stages: a voltage divider circuit for voltage transformation, followed by stages of transistors with progressively lower voltage requirements. This segmentation allows each stage to be optimized for its specific voltage range while maintaining overall radiation tolerance through the use of low-voltage CMOS technology.
Solution Approach 2:
The patent applies parameter transformation by converting high-voltage bus signals through a voltage divider into low-voltage signals suitable for radiation-tolerant CMOS transistors. This parameter change enables the driver to accommodate the full CAN bus voltage range while maintaining radiation tolerance through low-voltage technology.
4Reliability
If low-voltage transistors are used, then radiation tolerance is improved, but gate-drain voltage tolerance deteriorates
Solution Approach 1:
The voltage divider circuit acts as a protective intermediary between the high-voltage bus line and the low-voltage transistors. It ensures that the gate-drain voltage across the low-voltage transistors never exceeds their maximum ratings, even when the bus line experiences high voltages, thereby preserving both radiation tolerance and voltage safety.
Solution Approach 2:
The voltage divider circuit provides beforehand cushioning by pre-reducing the voltage from the bus line before it reaches the low-voltage transistors. This proactive voltage reduction prevents excessive gate-drain voltages from developing across the transistors, protecting them from both overvoltage damage and radiation-induced vulnerabilities.
Data Source
AI summary
A bi-state driver circuit for switching an output terminal between a first predetermined voltage level and a high impedance state, which involves a first string of transistors connected between the output terminal and the first predetermined voltage level at least a first transistor arranged closer to the first predetermined voltage level, a second transistor arranged closer to the output terminal, a voltage divider circuit connected between the output terminal and a voltage level of a control signal attaining voltage levels between the first predetermined voltage level and a second predetermined voltage level, including at least one intermediate node having an intermediate voltage level between a voltage level of the output terminal and the voltage level of the control signal, and a second string of transistors connected between the intermediate node of the voltage divider circuit and the second predetermined voltage level, and including at least a third transistor.