Current-Mirror Undervoltage Lockout Circuit Without Resistor Divider
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Solution Overview
Problem
Conventional undervoltage-lockout circuits have high power consumption and large layout area due to the use of resistors to divide system high voltage, necessitating a need for a more efficient design.
Innovation Solution
An undervoltage-lockout circuit utilizing a current mirror circuit, current source, and reference transistors to generate an undervoltage-lockout signal without dividing the system high voltage, thereby reducing power consumption and layout area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If resistors are used to divide system high voltage, then voltage division function is achieved, but power consumption increases and layout area increases
Solution Approach 1:
The patent changes the fundamental parameter from resistive voltage division to transistor-based current mirror voltage generation. By using transistors MP1 and MP2 in a current mirror configuration with current source CS1, the circuit generates the required voltages without dissipative resistors, thereby reducing both power consumption and layout area while maintaining the voltage division functionality.
2Use of energy by moving object
If resistance values of resistors are increased to reduce power consumption, then power consumption decreases, but layout area greatly increases
Solution Approach 1:
The patent replaces the passive resistive system with an active transistor-based current mirror system. This substitution eliminates the need for high-value resistors that would consume less power but occupy large areas. The current mirror transistors achieve the same voltage generation function with much smaller footprint and lower power consumption.
3Reliability
If conventional resistor-based voltage division is used, then voltage regulation is achieved, but device complexity and component count increase
Solution Approach 1:
The patent merges multiple functions into the transistor-based current mirror structure. The same transistors that generate the reference voltages also provide the voltage division ratio through their configuration. This integration reduces the number of discrete components compared to a traditional resistor divider network while maintaining reliable voltage regulation.
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
The proposed circuit significantly reduces power consumption and layout area by eliminating the need for resistors, while maintaining effective voltage regulation and hysteresis functionality.
Implementation Method 1
The current mirror circuit is coupled to a system high voltage. The current mirror circuit includes a first connection terminal and a second connection terminal. The current source is coupled to the first connection terminal. A first terminal of the first reference transistor is coupled to the second connection terminal.
Implementation Method 2
A first terminal of the first reference transistor is coupled to the second connection terminal. A second terminal of the first reference transistor provides a reference voltage.
Implementation Method 3
The comparison circuit is coupled to the second terminal of the first reference transistor and the first connection terminal. The comparison circuit receives an input voltage at the first connection terminal and the reference voltage. The comparison circuit generates an undervoltage-lockout signal according to the input voltage and the reference voltage.
Data Source
AI summary
An undervoltage-lockout circuit is provided. The undervoltage-lockout circuit includes a current mirror circuit, a current source, a first reference transistor, a second reference transistor, and a comparison circuit. The current mirror circuit includes a first connection terminal and a second connection terminal. The current source is coupled to the first connection terminal. A first terminal of the first reference transistor is coupled to the second connection terminal. A second terminal of the first reference transistor provides a reference voltage. A first terminal of the second reference transistor is coupled to the second terminal of the first reference transistor. A second terminal of the second reference transistor is coupled to a system low voltage. The comparison circuit receives an input voltage at the first connection terminal and the reference voltage. The comparison circuit generates an undervoltage-lockout signal according to the input voltage and the reference voltage.