Under Voltage Lockout Circuit with Band Gap Temperature Compensation
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Solution Overview
Problem
Existing under voltage lockout circuits lack effective temperature compensation, leading to instability in voltage detection and reference voltage generation, which can result in improper activation or shutdown of electronic circuits due to temperature-induced voltage fluctuations.
Innovation Solution
The proposed under voltage lockout circuit integrates a band gap circuit, amplifier, control unit, voltage divider, comparator, and current mirror circuit, which generates a reference voltage and under voltage lockout signal, utilizing bipolar junction transistors and resistors to amplify and mirror currents, ensuring stable voltage detection and temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage detection circuits are used without temperature compensation, then the circuit structure remains simple, but the voltage detection stability deteriorates due to temperature-induced voltage fluctuations
Solution Approach 1:
The patent combines the band gap reference circuit with the under voltage lockout detection circuit into a single integrated structure. The band gap circuit generates a temperature-compensated reference voltage that serves dual purposes: providing a stable reference for voltage detection and compensating for temperature effects on the detection threshold. This merging eliminates the need for separate temperature compensation circuits while maintaining detection stability.
Solution Approach 2:
The patent introduces a reference voltage generating circuit based on band gap technology as an intermediary element. This reference voltage acts as a mediator between the temperature variations and the voltage detection process, providing a temperature-stable reference point that compensates for thermal drift in the detection circuit. The reference voltage dynamically adjusts to counteract temperature-induced voltage changes in the main circuit.
2Reliability
If temperature compensation is added to the under voltage lockout circuit, then voltage detection stability improves, but the circuit complexity increases
Solution Approach 1:
The patent combines the band gap reference circuit with the under voltage lockout detection circuit into a single integrated structure. The band gap circuit generates a temperature-compensated reference voltage that serves dual purposes: providing a stable reference for voltage detection and compensating for temperature effects on the detection threshold. This merging eliminates the need for separate temperature compensation circuits while maintaining detection stability.
Solution Approach 2:
The reference voltage generating circuit performs multiple functions simultaneously: it provides a stable reference voltage for the under voltage lockout detection, compensates for temperature drift in the detection circuit, and serves as a temperature sensor for calibration purposes. This multi-functionality reduces the need for additional dedicated temperature compensation components, thereby limiting the increase in circuit complexity.
3Reliability
If band gap circuit is integrated with under voltage lockout circuit, then temperature compensation is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter scaling and normalization techniques in the band gap circuit design to reduce sensitivity to manufacturing variations. By carefully selecting and matching transistor sizes, resistor ratios, and current mirror scaling factors, the circuit achieves temperature compensation with reduced dependence on absolute component values. This approach relaxes manufacturing precision requirements while maintaining the temperature compensation function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration provides stable voltage detection and temperature-insensitive under voltage lockout signals, ensuring proper operation and data protection of electronic circuits by maintaining consistent voltage levels despite temperature changes.
Implementation Method 1
a band gap circuit 10, an amplifier 20, a control unit 30, a voltage divider 40
Implementation Method 2
The amplifier includes two input terminals electrically coupled to the two current input terminals of the band gap circuit respectively, and is configured to amplify a voltage difference between voltages on the current input terminals
Implementation Method 3
The current mirror circuit is electrically coupled to the first input terminal of the comparator and the band gap circuit, and configured to generate a second current flowing through the first resistor. The second current is mirrored from the first current
Implementation Method 4
the band gap circuit includes a first bipolar junction transistor (BJT), a second BJT and a second resistor, and the first BJT includes a base and a collector electrically coupled to each other and to a base of the second BJT
Data Source
AI summary
The present disclosure illustrates an under voltage lockout circuit in which a band gap circuit includes two current input terminals for generating a first current associated with band gap, an amplifier includes two inputs terminal coupled to the two current input terminal, and an output terminal configured to output an error-amplified signal, a terminal of a control device is coupled with a voltage source, and a control terminal of the control device receives the error-amplified signal, a voltage divider is coupled between current input terminals and other terminal of the control device, a comparator receiving a lockout voltage and outputting an under voltage lockout signal, a current mirror circuit is coupled to the first input terminal of the comparator and the band gap circuit, and configured to generate a second current mirroring from the first current.