Single Bandgap Comparator for Zero-Volt OV UV Detection
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Solution Overview
Problem
Existing systems require multiple band gap references to accurately detect overvoltage (OV) and undervoltage (UV) conditions, which increases power consumption and complexity, and fail to provide valid outputs at zero volts.
Innovation Solution
A single band gap reference circuit with a coarse comparator and pull-up circuits is used to detect OV and UV conditions, employing a resistor divider to adjust the trip point and maintain accurate detection across temperatures, with low power consumption and valid outputs down to zero volts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple band gap references are used to detect OV and UV conditions, then detection accuracy is improved, but power consumption and circuit complexity increase
Solution Approach 1:
The patent combines multiple band gap reference circuits into a single band gap reference circuit that serves both OV and UV detection functions. This merging eliminates the need for separate reference circuits, thereby reducing power consumption and circuit complexity while maintaining detection accuracy through shared reference voltage generation.
Solution Approach 2:
The single band gap reference circuit is designed to provide reference voltages for both OV and UV detection thresholds simultaneously. This multi-functional approach allows one circuit to perform the work of multiple circuits, reducing overall power consumption while maintaining the precision needed for both detection functions.
2Measurement precision
If multiple band gap references are used to detect OV and UV conditions, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges multiple band gap reference circuits into a single integrated circuit that provides reference voltages for both OV and UV detection. This consolidation reduces the number of components, simplifies the circuit architecture, and maintains detection accuracy through proper voltage division and comparison logic.
Solution Approach 2:
The single band gap reference circuit is segmented to provide multiple reference voltage levels through a resistor divider network. This segmentation allows the circuit to generate distinct threshold voltages for OV and UV detection without requiring separate band gap references, thereby reducing complexity while maintaining precision.
3Reliability
If standard detection circuits are used, then OV and UV conditions can be detected, but valid outputs are not provided at zero volts
Solution Approach 1:
The patent inverts the traditional detection approach by using a single band gap reference that remains operational at zero volts. Instead of requiring separate references for different voltage ranges, the inverted approach uses one reference with a comparator that can validly detect both OV and UV conditions across the entire voltage range including zero volts, ensuring continuous output validity.
Data Source
AI summary
Systems and methods for overvoltage and undervoltage detection may be implemented with a fully differential circuit that includes a coarse comparator and a band gap based fine comparator. The coarse comparator may determine if the battery is closer to an OV condition or an UV condition. Based on the output of the coarse comparator, the trip point of the fine comparator is adjusted. The outputs of both comparators are pull-up circuits whose output is decoded to determine if an OV or a UV condition has occurred. The systems and methods accomplish valid circuit outputs even when the voltage across the battery reduces to zero volts. This may be achieved by using an active low signal for the UV condition and an active high signal for the OV condition. Thus, when the battery voltage goes to zero, the circuit evaluates to the correct output.