Active Driver SENT Bus Circuit for Faster One-Wire Rise Time
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Solution Overview
Problem
The rise-time of low-to-high transitions on a one-wire bus in the Singled Edge Nibble Transmission (SENT) protocol is slow due to reliance on passive pull-up resistors, which limits bus speed in certain applications.
Innovation Solution
Incorporating active pull-up and pull-down elements, such as field-effect transistors (FETs), to actively control the voltage levels on the bus, allowing for faster rise times during data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If passive pull-up resistors are used to maintain logic-high voltage level, then the SENT protocol can be implemented with simple circuitry, but the rise-time of low-to-high transitions becomes slow, limiting bus speed
Solution Approach 1:
The patent changes the electrical parameters of the pull-up mechanism by replacing passive resistors with active FET-based switches. This allows dynamic control of the pull-up strength, enabling fast rise times when needed while maintaining protocol compatibility. The active elements can provide much higher current drive capability compared to passive resistors, directly addressing the speed limitation.
Solution Approach 2:
The patent introduces dynamic control of the pull-up mechanism using FET switches that can be actively turned on and off. This dynamic approach allows the system to adapt the pull-up strength based on communication requirements, providing fast rise times during data transmission while consuming less power when idle. The dynamic nature of FET-based pull-up resolves the contradiction between speed and complexity by providing conditional performance enhancement.
2Reliability
If passive pull-up resistors are used, then the circuit implementation is simple, but the rise-time becomes a function of supply voltage and resistor value variations, reducing reliability
Solution Approach 1:
The patent transforms the fixed parameter approach of passive resistors into a controllable parameter system using active FET elements. The FET-based pull-up can maintain consistent rise times across varying supply voltages and temperature conditions by actively regulating the charging current. This parameter control capability directly improves transition time consistency and reliability while compensating for component variations.
Solution Approach 2:
The patent implements feedback control through the active management of FET gate signals, which can respond to bus conditions and adjust the pull-up strength accordingly. This feedback mechanism ensures that rise times remain consistent even when external conditions change, directly addressing the reliability concern associated with passive resistor-based pull-up that lacks adaptive capability.
3Use of energy by moving object
If larger pull-up resistors are used to reduce power consumption, then power usage decreases, but the rise-time increases further, slowing down communication
Solution Approach 1:
The patent applies dynamic control to resolve the power-speed tradeoff. During active communication, the FET-based pull-up elements are turned on to provide fast rise times and high-speed communication. During idle periods, the pull-up elements can be turned off or placed in high-impedance state, dramatically reducing power consumption. This dynamic switching capability allows the system to achieve both low power consumption and high speed when needed, eliminating the need to choose one over the other.
Solution Approach 2:
The patent utilizes periodic activation of the active pull-up elements synchronized with the communication protocol's timing requirements. Pull-up strength is applied periodically only when data transmission requires it, rather than continuously. This periodic action pattern reduces average power consumption while maintaining high-speed communication capability during active data transfer periods.
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 active elements significantly reduce the rise time of voltage transitions, enhancing the communication speed and efficiency of the SENT protocol.
Implementation Method 1
Incorporating active pull-up and pull-down elements, such as field-effect transistors (FETs), to actively control the voltage levels on the bus
Data Source
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AI summary
A serial communication system includes transmission line and at least one slave device. The at least one slave device comprises an active pull-down element coupled to the transmission line to pull a voltage on the transmission line low during transmission, an active pull-up element coupled to the transmission line to pull the voltage on the transmission line high during or after transmission, and a communication circuit configured to transmit data onto the transmission line according to a SENT protocol by activating the pull-down element and the pull-up element.