LIN Receiver Wake-Up Circuit for Low-Power Bus Level Detection
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Solution Overview
Problem
Current LIN receivers have high power consumption in sleep mode due to the permanent operation of voltage divider chains, which prevents accurate level detection on the LIN bus and wake-up functionality.
Innovation Solution
A LIN receiver with sleep/wake-up functionality that uses transistors to activate the receiver upon a state change on the LIN bus, eliminating the need for high-impedance voltage dividers and allowing for low power consumption in recessive states, with automatic activation upon bus activity and proportional hysteresis to the supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage divider chains are permanently operated to detect LIN bus levels, then level detection accuracy is maintained, but power consumption increases in sleep mode
Solution Approach 1:
The patent extracts the essential detection function from the permanent voltage divider chain by using a wake-up circuit that is only activated when needed. The voltage divider is replaced by a combination of pull-up resistor and wake-up transistor that only consumes significant power during active detection, not during sleep mode.
Solution Approach 2:
Instead of continuous operation, the patent implements periodic activation of the detection circuitry through the wake-up mechanism. The receiver remains in sleep mode with minimal power consumption and only activates the full detection circuit when a wake-up event occurs on the LIN bus.
2Use of energy by moving object
If voltage divider chains are switched off to reduce power consumption, then power consumption decreases in sleep mode, but wake-up functionality via LIN bus is lost
Solution Approach 1:
The patent prepares a dedicated wake-up circuit with transistor M1 and resistor R1 that remains in standby mode during sleep. This preliminary setup allows the circuit to quickly respond to wake-up events without needing to maintain the full voltage divider chain active, enabling both low power consumption and wake-up functionality.
Solution Approach 2:
The patent introduces a wake-up transistor (M1) as an intermediary element that mediates between the sleep mode and active mode. This transistor acts as a switch that can be triggered by bus activity to activate the full receiver circuitry, providing wake-up functionality without requiring permanent operation of the main detection circuit.
3Measurement precision
If high-impedance resistors are implemented for accurate level evaluation, then measurement precision improves, but chip area increases
Solution Approach 1:
The patent changes the operational parameters of the detection circuit by using transistors with controlled impedance rather than fixed high-impedance resistors. The transistors can dynamically adjust their impedance characteristics, providing accurate level detection only when needed while occupying less chip area than permanent high-impedance resistor implementations.
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
Achieves very low power consumption in sleep mode with minimal current leakage, enabling automatic activation and low power operation in active mode without a separate wake-up signal, while maintaining accurate signal evaluation and compliance with LIN specifications.
Implementation Method 1
a first and a second resistor R1, R2 which form a voltage-to-current converter SSW
Implementation Method 2
at least a first, second and third of the transistors are preferably connected to mirror the current flow through the first resistor
Data Source
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AI summary
The invention relates to a LIN receiver providing sleep/wake up functionality and comprising an input (LINI) to a LIN bus (LIN), an output (RXDO), connections for at least one supply voltage (BVDD) and transistors (M1-M17). The transistors (M1-M17) are connected to activate the receiver in the recessive state of the LIN bus by switching the state at the LIN bus into an active state of the receiver. In particular, the input (LINI) is connected between components of a voltage-to-current converter (SSW), in particular between a first and a second resistance (R1, R2).