Active Pull-Up SENT Bus Circuit for Faster Rise Times
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Solution Overview
Problem
The SENT protocol's reliance on passive pull-up resistors limits bus speed due to slow rise times during transmissions, which can be a bottleneck in certain applications.
Innovation Solution
Incorporating active pull-down and pull-up elements, such as FETs, to control the voltage on the transmission line, allowing for faster transitions between logic-high and logic-low states, thereby improving communication speed and immunity to interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive pull-up resistors are used to maintain the one-wire bus at logic-high voltage level, then the SENT protocol can be implemented with simple circuitry, but the bus speed is limited due to slow rise times during transmissions
Solution Approach 1:
The patent changes the electrical parameters of the pull-up mechanism by replacing the passive resistor with an active transistor-based circuit that can dynamically adjust its resistance. The active pull-up circuit transitions between high-impedance and low-impedance states, enabling fast rise times while maintaining circuit simplicity through standardized transistor configurations.
Solution Approach 2:
The patent substitutes the passive electrical resistance mechanism with an active electronic switching mechanism using transistors. This replacement enables controlled, rapid voltage transitions by using transistor switching action rather than relying on passive RC time constants, thereby increasing bus speed without significantly increasing overall circuit complexity.
2Ease of manufacture
If passive pull-up resistors are used, then the circuit implementation is simple, but the rise time of low-to-high transitions is slow due to dependence on supply voltage and resistor value
Solution Approach 1:
The patent introduces dynamic behavior to the pull-up circuit by using transistors that can rapidly switch between conducting and non-conducting states. This dynamic switching capability allows the circuit to adapt its resistance in real-time, providing fast rise times when needed while maintaining simple static operation during idle periods, thus resolving the contradiction between simplicity and speed.
Solution Approach 2:
The active pull-up circuit is pre-configured and ready to activate immediately when a low-to-high transition is required. Unlike passive resistors that continuously limit current, the active circuit can be preliminarily prepared in a high-impedance state and then rapidly switched to a low-impedance state, eliminating the need to wait for RC charging and reducing rise time without complicating the idle circuit state.
3Use of energy by moving object
If the pull-up resistor value is increased to reduce power consumption, then energy efficiency improves, but the rise time increases further slowing down communication
Solution Approach 1:
The patent employs periodic or pulsed activation of the active pull-up circuit rather than continuous operation. The transistor-based pull-up is activated only during the brief periods when voltage transitions are needed, and remains in a high-impedance state during idle periods. This periodic action dramatically reduces average power consumption while maintaining fast rise times when the circuit is actively switching.
Solution Approach 2:
The dynamic resistance characteristic of the active pull-up circuit allows it to present low resistance during transitions (enabling fast rise times) and high resistance during idle periods (reducing power consumption). This dynamic adaptation resolves the contradiction by allowing the circuit to optimize both speed and power efficiency at different operational moments rather than being constrained by a fixed resistor value.
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 enable faster rise times and improved communication efficiency, addressing the speed limitations of the SENT protocol by actively managing the bus voltage, enhancing data transmission speed and reliability.
Implementation Method 1
an active pull-down element coupled to the transmission line to pull a voltage on the transmission line low during transmission
Implementation Method 2
an active pull-up element coupled to the transmission line to pull the voltage on the transmission line high during or after transmission
Data Source
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.