Shared-Pin Circuit Structure for Analog-Digital Multiplexing
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Solution Overview
Problem
The increasing number of functions in circuits is limited by the number of available pins, necessitating pin multiplexing to enable efficient signal transmission, particularly in power-drive circuits where temperature monitoring is crucial for preventing damage.
Innovation Solution
A circuit structure that combines an MCU module, temperature sensing circuit, and functional module, utilizing a temperature sensing output curve to multiplex analog and digital signals, allowing shared pin usage through open-drain output modes and appropriate reference voltages, thereby enabling effective pin multiplexing and enhanced signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pin multiplexing is implemented to increase the number of functions, then the number of available functions increases, but the circuit complexity increases
Solution Approach 1:
The patent combines temperature sensing output and enable signal output into a single shared pin. The temperature sensing circuit and enable signal circuit both connect to the same pin, allowing one pin to perform multiple functions. This merging approach increases the number of available functions without proportionally increasing the pin count, thereby addressing the technical contradiction.
Solution Approach 2:
The shared pin is designed to serve multiple purposes: it can output temperature sensing signals to the MCU, transmit enable signals for functional modules, and support open-drain output modes for both analog and digital signals. This multi-functionality allows a single pin to replace what would traditionally require multiple dedicated pins, resolving the contradiction between increased functionality and circuit complexity.
2Quantity of substance
If analog and digital signals share the same pin, then the number of pins required decreases, but signal interference may increase
Solution Approach 1:
The patent employs periodic or conditional signal transmission where the temperature sensing circuit and enable signal circuit take turns or operate in different modes on the shared pin. The MCU controls the timing and mode of signal transmission, allowing analog temperature signals and digital enable signals to share the pin without continuous simultaneous operation, thereby reducing signal interference while minimizing pin usage.
Solution Approach 2:
The open-drain output structure acts as an intermediary mechanism that facilitates safe sharing of the pin between analog and digital circuits. The open-drain configuration with pull-up resistors provides electrical isolation and conflict resolution, allowing different signal types to share the same physical connection without causing harmful interference, thus enabling pin reduction while managing signal compatibility.
Data Source
AI summary
A circuit structure for realizing circuit pin multiplexing, comprising an MCU module, a temperature sensing circuit and a functional module circuit. The output end of the temperature sensing circuit is connected with an enable signal interface of the MCU module, the output voltage of the temperature sensing circuit is always higher than the threshold voltage of the enable signal, and the MCU module is connected with the functional module circuit. The circuit structure of the present invention realizes the mutual influence of analog signal output and digital signal transmission by designing a temperature sensing output curve, and achieves multi-function multiplexing of a single pin, so that the output of the analog signal and the input of the digital signal can share the pins, it solves the problem of the limitation of the number of pins, and promotes the transmission of the signal and improves the cost performance of the circuit.