Open-Drain Bus Repeater With Threshold Pull-Up Acceleration
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Solution Overview
Problem
Existing open-drain bus repeaters for I2C communication systems face challenges in detecting pull-down events, especially when the supply voltage is low, and struggle with reducing rise time for voltage transitions, which affects communication efficiency and system implementation complexity.
Innovation Solution
The proposed bus repeater includes a repeating unit with A-side and B-side terminals, featuring accelerator elements and control units that manage voltage thresholds and pull-down operations to enhance signal transmission speed and detection accuracy, utilizing transistors and buffers to control voltage transitions and detect external pull-down events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing open-drain bus repeaters are used, then the system can maintain basic communication functionality, but the rise time for voltage transitions is excessive and detection of pull-down events is unreliable especially at low supply voltages
Solution Approach 1:
The repeater proactively monitors the bus line voltage and detects pull-down events before they complete, enabling early response. The accelerator element is pre-positioned and can be activated immediately upon detection, rather than waiting for the full transition to occur. This preliminary detection and preparation reduces the effective rise time and improves reliability of event detection.
Solution Approach 2:
The patent changes the electrical parameters of the bus line by introducing an accelerator element that actively modifies the voltage transition characteristics. The accelerator alters the rise time constant by providing additional current paths, effectively changing the RC time constant of the bus line to achieve faster voltage transitions while maintaining detection accuracy.
2Speed
If accelerator elements are added to reduce rise time, then voltage transition speed improves, but device complexity increases
Solution Approach 1:
The accelerator element is merged with the existing repeater structure, sharing common components such as the control logic and bus line connections. The accelerator is integrated into the repeater's voltage regulation circuitry, combining multiple functions (voltage monitoring, acceleration, and pull-down detection) into a unified structure rather than adding separate independent components.
Solution Approach 2:
The accelerator element serves multiple functions: it accelerates voltage transitions during normal operation, assists in pull-down event detection by providing reference current paths, and can be dynamically controlled to adapt to different bus conditions. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity.
3Ease of manufacture
If the repeater structure is simplified to reduce complexity, then ease of manufacture improves, but the ability to detect pull-down events and control voltage transitions deteriorates
Solution Approach 1:
The patent applies local quality by enhancing only the critical portions of the repeater structure where detection and acceleration functions are needed, rather than uniformly complicating the entire device. The accelerator element is strategically positioned at specific points on the bus line where it provides maximum detection sensitivity and acceleration effect, allowing simple structures elsewhere in the circuit.
Data Source
AI summary
A repeater for open-drain bus communication and a system including the same is provided. The repeater includes at least one repeating unit having an A-side terminal connected to an A-side open-drain bus, and a B-side terminal electrically connected to a B-side open-drain bus. The repeater has a first mode to receive a signal at the A-side and to produce a signal at the B-side. The repeating unit includes a B-side accelerator element connected to the B-side terminal. The repeating unit when in a first mode includes a first control unit to, control the B-side accelerator element to pull up a voltage at the B-side when the voltage at the A-side surpasses a first threshold voltage during a rising edge of the voltage, and to subsequently control the B-side accelerator element to stop pulling up the voltage at the B-side when the voltage at the B-side surpasses a second threshold voltage.