Reference Resistor Detection Circuit Without Extra IC Pins
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Solution Overview
Problem
Existing solutions for sensing the resistance of an external reference resistor require a dedicated pin or terminal on integrated circuits, increasing the size and cost of IC packages.
Innovation Solution
A system that includes an operational amplifier, switches, bias current sources, transistors, and capacitors to detect the resistance of an external resistor without the need for additional pins, using a feedback path to provide an output current corresponding to the resistor's resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated pin or terminal is used for sensing the external reference resistor, then the resistance sensing function is achieved, but the number of IC pins increases and package size increases
Solution Approach 1:
The existing IC pins are made multi-functional by implementing resistance sensing capabilities within the voltage supply path. The system uses the same pins that provide power and control signals to also sense the external reference resistor value, eliminating the need for dedicated sensing pins. This is achieved through circuitry that can detect voltage drops or current flows through existing pin connections during normal operation.
Solution Approach 2:
The resistance sensing function is merged with the existing voltage supply and control functions. The patent combines multiple functions (power supply, control signaling, and resistance sensing) into a single integrated system that operates through the existing pin structure, thereby eliminating separate dedicated pins for resistance sensing.
2Measurement precision
If a dedicated pin or terminal is used for sensing the external reference resistor, then the resistance sensing function is achieved, but the fabrication cost increases
Solution Approach 1:
By making existing pins multi-functional, the patent eliminates the need for additional dedicated sensing pins, which reduces the pin count and simplifies the IC package design. This reduction in pin count directly translates to lower fabrication costs due to fewer external connections required and simpler packaging processes.
Solution Approach 2:
The sensing function is extracted and integrated into the existing voltage supply path circuitry rather than requiring separate external sensing components or dedicated pins. This integration approach reduces the overall system complexity and manufacturing steps required.
Data Source
AI summary
A system includes an operational amplifier which includes a first amplifier input, a second amplifier input and an amplifier output. The system includes a first switch which includes a first terminal and includes a second terminal coupled to the first amplifier input. The system includes a second switch which includes a first terminal coupled to the first amplifier input and a second terminal coupled to the second amplifier input. The system includes a first bias current source coupled between the first amplifier input and a common potential and includes a second bias current source coupled between the first terminal of the first switch and the common potential. The system includes a feedback path between the amplifier output and the first amplifier input.