Hybrid Output Buffer for Swappable 1-Wire I/O and CAP Pins
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Solution Overview
Problem
The 1-Wire communications bus architecture lacks flexibility in pin configuration, limiting the ability to differentiate peripherals and efficiently use printed circuit board space, as existing solutions require separate versions for 'left-handed' and 'right-handed' layouts and do not allow for swappable I/O and CAP pins.
Innovation Solution
The implementation of swappable pins in a 1-Wire system that can function as either I/O or CAP pins, with a hybrid buffer circuit and charging mechanisms for efficient capacitor charging, allowing for detection of pin configurations and enabling different device IDs based on pin connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate versions of peripherals are used for left-handed and right-handed PCB layouts, then PCB layout flexibility is improved, but device complexity and component count increase
Solution Approach 1:
The peripheral device is designed with swappable pin functionality where pins can be configured as either I/O pins or CAP pins depending on the connection detected. This universal design allows a single device version to adapt to both left-handed and right-handed PCB layouts, eliminating the need for separate versions while maintaining layout flexibility.
Solution Approach 2:
The pin configuration is made dynamic through detection circuits that identify whether a pin is connected to an I/O line or a CAP line at startup. Based on this detection, the device dynamically determines its orientation and configures its pins accordingly, allowing adaptation to different PCB layouts without physical reconfiguration.
2Adaptability or versatility
If conventional buffer circuits are used for swappable pins, then pin configuration flexibility is improved, but IC area and leakage increase
Solution Approach 1:
The buffer circuit is merged into a hybrid configuration where a single PFET pull-up device serves both I/O and CAP pin functions. Instead of having separate buffer circuits for each pin type, the invention combines functionality so that one buffer structure handles both configurations, reducing IC area while maintaining pin flexibility.
Solution Approach 2:
The hybrid buffer circuit is designed as a universal structure that can operate in both I/O mode and CAP pin mode. The same PFET device and associated circuitry provide buffering functionality regardless of which pin configuration is active, eliminating the need for duplicate circuitry and reducing overall IC area.
3Adaptability or versatility
If detection circuits are added to determine pin configurations, then adaptability is improved, but device complexity increases
Solution Approach 1:
The detection circuit operates autonomously at startup without requiring external control signals. It automatically detects whether each pin is connected to an I/O line or a CAP line by monitoring voltage levels or current flow, and this self-detection capability is built into the basic device structure, minimizing additional complexity while maximizing adaptability.
Solution Approach 2:
Pin configuration detection is performed preliminarily during startup before the device begins normal operation. This preliminary detection allows the device to pre-configure its pins and internal circuits according to the detected layout, ensuring proper operation from the outset without requiring complex runtime reconfiguration mechanisms.
4Productivity
If swappable pin configuration is implemented, then PCB layout efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The detection circuit is designed with sufficient noise margins and voltage threshold tolerances to accommodate normal manufacturing variations and connection tolerances. By building in these protective margins beforehand, the system can reliably detect pin configurations even when connections are at the extremes of acceptable manufacturing tolerances, reducing the stringency of precision requirements.
Data Source
AI summary
Circuits and methods for determining the characteristics of swappable pins in a peripheral in a 1-Wire or similar single-conductor system, thereby allowing each one of two pins to be either an I/O pin (connected to an I/O line) or a CAP pin (connected to a storage capacitor). Embodiments may utilize a hybrid buffer circuit that utilizes an effectively bi-directional PFET pull-up device coupled between the swappable pins A and B. Two open-drain NFETs pull-down devices are used, one on either side of the PFET and coupled to a respective pin (A or B), but with only one NFET being selected to be operable based on pin-determination flag signals from the pin detection circuitry. Such a hybrid buffer circuit would consume significantly less IC area than two complete conventional buffers, resulting in less leakage and less yield loss.