CAN Bus Transceiver Voltage Boosting for Low-Emission Mixed-Voltage Operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge of mixed operation in CAN bus systems, where devices with different voltage levels (5V and 3.3V) cause significant electromagnetic emissions and EMC interference, is not easily addressed by existing technologies, especially when transitioning between dominant and recessive states.
Innovation Solution
A transmitting/receiving device with a transformation block that adjusts the supply voltage to a higher value, allowing devices with different voltage levels (e.g., 3.3V and 5V) to operate on a bus system by generating the required zero line voltage levels, thereby reducing electromagnetic emissions and ensuring error-free communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the supply voltage is reduced from 5V to 3.3V to reduce costs and match microcontroller voltages, then cost and power consumption are improved, but electromagnetic emissions increase and EMC compliance becomes difficult
Solution Approach 1:
The patent introduces a voltage transformation block as an intermediary between the 3.3V supply and the transceiver circuitry. This block transforms the 3.3V supply voltage into a higher voltage (5V or higher) that enables the transceiver to generate proper differential voltage levels on the bus, thereby reducing electromagnetic emissions while maintaining compatibility with 3.3V microcontrollers
Solution Approach 2:
The patent changes the voltage parameter through the transformation block, which dynamically adjusts the voltage supplied to the transceiver based on the operating mode (dominant or recessive state). This allows the system to maintain proper voltage levels for EMC compliance while operating from a 3.3V supply
2Adaptability or versatility
If devices with different voltage levels (5V and 3.3V) operate simultaneously on the same bus, then adaptability and versatility are improved, but electromagnetic emissions increase and communication reliability deteriorates
Solution Approach 1:
The transformation block acts as an intermediary that enables 3.3V devices to communicate reliably with 5V devices on the same bus. By transforming the supply voltage to match the required bus voltage levels, it eliminates the voltage level mismatch that would otherwise cause communication errors and increased emissions
Solution Approach 2:
The patent creates equipotential conditions on the bus by ensuring that all devices, regardless of their supply voltage, generate the same differential voltage levels (CAN_H and CAN_L) on the bus. The transformation block ensures that 3.3V devices produce the same voltage levels as 5V devices, eliminating potential conflicts
3Use of energy by moving object
If the supply voltage is reduced to 3.3V, then power consumption is reduced, but the ability to generate proper differential voltage levels for dominant and recessive states becomes compromised
Solution Approach 1:
The transformation block serves as an intermediary power conversion stage that takes the 3.3V supply and converts it to the higher voltage levels needed by the transceiver to generate proper differential signals. This allows the system to consume less power from the supply while maintaining accurate signal levels on the bus
Solution Approach 2:
The transformation block uses periodic switching action (charge pump mechanism) to generate the higher voltage levels from the 3.3V supply. By switching at appropriate frequencies synchronized with the communication protocol, it maintains proper voltage levels during dominant and recessive states while averaging lower power consumption
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
The solution enables reliable, low-emission, and cost-effective operation of mixed voltage devices on a CAN bus system, maintaining high bit rates and minimizing electromagnetic interference.
Implementation Method 1
a transformation block (225) connected between the terminal for the external voltage source and the transmitting/receiving block (220), wherein the transformation block (225) is designed to transform a supply voltage applied to the terminal into a voltage which has a higher voltage value than the supply voltage applied to the terminal
Data Source
AI summary
A transmitting/receiving device for a subscriber station of a serial bus system. The transmitting/receiving device has a transmitting/receiving block for transmitting a digital transmit signal as an analog differential signal to a bus of the bus system to transmit a message to at least one other subscriber station of the bus system and/or for receiving an analog signal from the bus, a transformation block for outputting a voltage as a voltage supply for the transmitting/receiving block, and a terminal for an external voltage source. The transformation block is connected between the terminal for the external voltage source and the transmitting/receiving block. The transformation block is designed to transform a supply voltage applied to the terminal into a voltage which has a higher voltage value than the supply voltage applied to the terminal. A method is also described.