Current-Mode Low-Voltage Shutdown Circuit for Precise Thresholds
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Solution Overview
Problem
Existing electronic circuits face challenges in shutting down reliably when voltage or current falls below a threshold, especially at low current levels, while maintaining compatibility with various logic standards and temperature variations.
Innovation Solution
A low voltage shutdown circuit is designed with first and second voltage-to-current converters whose transfer functions intersect at a non-zero threshold voltage, enabling a precise and repeatable shutdown signal even at currents as low as 1 μA, using a current comparison circuit to toggle the shutdown output based on the difference between the converted currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage monitoring circuits are used, then shutdown function is provided, but the threshold point becomes undefined or inconsistent at low current levels
Solution Approach 1:
The patent replaces conventional voltage comparison circuits with a current-based comparison system. By converting the monitored voltage to current through V-to-I converters and using current mirrors to generate reference currents, the system achieves precise threshold detection in the low-current regime where conventional voltage-based circuits fail to provide consistent threshold points.
Solution Approach 2:
The patent changes the fundamental parameter used for threshold detection from voltage to current. By operating in the current domain rather than voltage domain, the circuit achieves well-defined threshold points even when available current is as low as 1 μA or less, resolving the inconsistency problem of conventional voltage-based monitoring at low current levels.
2Use of energy by moving object
If the circuit is designed to operate at very low current levels, then power consumption is reduced, but the ability to maintain a defined threshold point deteriorates
Solution Approach 1:
The patent substitutes voltage-based threshold detection with current-based detection using current mirrors and V-to-I converters. This substitution enables the circuit to maintain well-defined threshold points even when operating at extremely low current levels (1 μA or less), allowing ultra-low power operation without sacrificing threshold definition.
Solution Approach 2:
The patent creates a universal threshold detection mechanism that functions reliably across a wide range of current levels, from very low (1 μA) to higher currents. The current-based comparison circuit with programmable reference currents provides consistent threshold detection regardless of the operating current level, enabling the same circuit to serve both ultra-low power and higher power applications.
3Adaptability or versatility
If the threshold voltage is made adjustable for different logic standards, then compatibility is improved, but circuit complexity increases
Solution Approach 1:
The patent achieves adjustable threshold voltage for different logic standards by programmably setting reference current levels in the current comparison circuit. By changing current parameters rather than voltage parameters, the circuit can be configured for various logic standards (TTL, CMOS, etc.) without increasing complexity, as the same current-based architecture handles all standard adaptations.
Data Source
AI summary
A low voltage shutdown circuit comprises an input node for receiving a voltage Vin to be monitored, first and second voltage-to-current (V to I) converters arranged to receive Vin at respective inputs and to convert Vin to currents I1 and I2 at respective outputs, and a current comparison circuit arranged to produce an output which is in a first state when I1<I2 and in a second state when I1>I2. The V to I converters have respective voltage-to-current transfer functions which intersect at a non-zero threshold voltage Vth, such that the current comparison circuit output toggles when Vin<Vth. This output can be used as needed to, for example, trigger the shut down of other circuitry.