Single-Pin Serial Interface Circuit for Flexible PWM Configuration
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Solution Overview
Problem
Small electronic systems with a single input pin, such as DC/DC converters, face limitations in configuring settings and mode selection due to the need for external resistor networks and I2C interfaces, which increase cost and die space.
Innovation Solution
A serial interface circuit that utilizes a single logic input pin for both static digital control signals and serial digital data, employing a decoder with an up/down counter and edge detection circuit to convert pulse-coded signals into logic values, allowing flexible bit timing and transmission rates, and enabling the pin to function as both an input and output for mode selection and data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If I2C interface is used for digital programming, then configuration flexibility is improved, but die space and system cost increase considerably
Solution Approach 1:
The single input pin is designed to perform multiple functions: it can receive static digital control signals (mode selection) and also accept serial digital data for configuration, eliminating the need for separate I2C interface circuitry and reducing die space while maintaining configuration flexibility
2Adaptability or versatility
If I2C interface is used for digital programming, then configuration flexibility is improved, but system cost increases considerably
Solution Approach 1:
The input pin serves dual purposes as both mode selection input and configuration data input, eliminating the need for expensive I2C interface hardware and reducing overall system cost while preserving digital programming capability
Solution Approach 2:
The patent extracts the configuration functionality from a dedicated I2C interface and implements it through the existing single input pin using pulse width encoding, removing the need for additional expensive interface circuitry
3Device complexity
If a single input pin is used for both mode selection and serial data, then device complexity is reduced, but signal timing requirements become more stringent
Solution Approach 1:
The patent transforms the input signal from simple logic levels to pulse width encoded signals where data is represented by varying pulse durations, allowing the decoder to distinguish between mode selection and data transmission based on timing characteristics rather than additional hardware
4Productivity
If pulse width coded signals are used for data transmission, then transmission rate flexibility is improved, but duty cycle requirements become more critical
Solution Approach 1:
The decoder uses an up/down counter that responds to rising and falling edges of the input signal, translating pulse width variations into logic levels based on whether the counter exceeds a reset value, providing flexibility in transmission rates while maintaining stable operation through counter-based decoding rather than fixed duty cycle requirements
Data Source
AI summary
A serial interface circuit for a single logic input pin of an electronic system, comprising a decoder for converting a pulse width modulated input signal applied to the pin to a sequence of logic low and logic high values. The decoder comprises an up/down counter with a count input connected to a clock source, an edge detection circuit detecting rising and falling edges of the input signal. The edge detection circuit is connected to the up/down counter to start up counting from a reset value upon detection of an edge in a first direction and to start down counting from a current count upon detection of an edge in a second direction. The decoder further comprises a bit value deciding circuit that delivers a first logic value when the count of the up/down counter is above the reset value on detection of an edge in the second direction and delivers a second logic value when the count of the up/down counter is at or below the reset value on detection of an edge in the second direction.