Configurable Circuitry Default Configuration via External Terminal
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Solution Overview
Problem
Conventional integrated circuits face challenges in accurately testing and configuring input/output ports due to indeterminate states of EEPROM cells before configuration, requiring additional external pins for testing, which increases cost and pin count, especially for small-scale devices.
Innovation Solution
The integrated circuit uses existing external terminals for defining a default configuration state of the input/output port, allowing for reliable testing and characterization without additional pins, by employing a multiplexer to route internal signals to an external terminal and comparator logic to determine the default configuration based on a pre-defined logic level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional external pins are added for testing configurable circuitry before configuration, then testing reliability is improved, but pin count and device complexity increase
Solution Approach 1:
The patent makes existing external terminals serve dual purposes: they function as normal I/O terminals during operational modes and as test configuration terminals during testing. The multiplexer routes internal test signals to these existing terminals, allowing them to universally serve both operational and testing functions without requiring additional pins.
Solution Approach 2:
The existing external terminals service themselves by performing both their primary I/O function and their secondary testing function. The circuitry uses the terminals' own signal lines to apply test patterns and capture test results, eliminating the need for separate dedicated test pins.
2Measurement precision
If additional external pins are added for testing configurable circuitry, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The multiplexer acts as an intermediary that enables precise measurement by routing internal test signals through existing external terminals. It mediates between the internal configurable circuitry and the external testing equipment, allowing accurate characterization without adding structural complexity.
Data Source
AI summary
An integrated circuit with a configurable portion, such as an input/output port, that can be placed in a default configuration prior to actual configuration of the integrated circuit. An external terminal that serves as an output during normal operation is coupled, after power-on of the integrated circuit, to a comparator that senses the voltage level at that external terminal. If the external terminal is at a particular level, a multiplexer is controlled to ignore the state of the normal configuration memory, and to place the configurable input/output port into a default protocol.