DC-DC Converter Mode Detection With Low-Leakage Power Source Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing DC-DC converters face challenges in efficiently detecting and switching between different power sources, such as low and high voltage batteries, leading to increased power consumption and reduced battery life, especially when using low-capacity batteries like silver-oxide button cells.
Innovation Solution
A mode detector is designed to determine the circuit mode based on the attached power source using a combination of latches, AND gates, OR gates, and switches, which reduces current draw by disconnecting power-on-reset signals once the mode is detected, and includes a maximum voltage selector to ensure proper operation with a voltage difference of at least 0.3V between power sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous power-on-reset monitoring is implemented to detect power source changes, then reliability is improved, but power consumption increases
Solution Approach 1:
The power-on-reset circuit operates periodically rather than continuously. The reset signal is generated only when power is first applied or when voltage thresholds are crossed, allowing the system to enter a low-power state afterward while still maintaining the ability to detect power source changes when they occur.
Solution Approach 2:
The voltage divider networks and threshold detection circuits are pre-configured to automatically detect when power source voltage changes occur. This preliminary detection mechanism triggers the mode detector before continuous monitoring would be required, reducing ongoing power consumption while maintaining reliability.
2Measurement precision
If both power source lines are continuously monitored to detect mode changes, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The voltage divider networks use passive resistive elements that automatically establish voltage thresholds based on the power source voltages themselves. This self-service mechanism eliminates the need for active monitoring components, achieving precise voltage detection without continuous current draw.
Solution Approach 2:
The voltage divider circuits act as intermediary elements between the power source lines and the mode detector. They transform the voltage information into threshold-crossing signals that can be detected without requiring continuous high-precision analog monitoring, thereby reducing power consumption while maintaining detection precision.
3Speed
If mode detector remains active to quickly detect power source changes, then speed is improved, but power consumption increases
Solution Approach 1:
The mode detector is designed to be active only during power transitions or mode changes. Once the mode is detected and stabilized, the detector enters a low-power state. The circuit quickly reactivates when voltage thresholds indicate a power source change, achieving fast detection speed without continuous operation.
Solution Approach 2:
The power-on-reset circuit and voltage threshold detectors are pre-configured to immediately sense power source changes. This preliminary detection capability allows the mode detector to activate quickly when needed, achieving fast response without requiring the detector to remain continuously active.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Various embodiments relate to a mode detector configured to determine a mode of a circuit based upon an attached power source, including: a first latch configured to hold an first input value and output the first held value and an inverse of the first held value; a second latch configured to hold a second input value and output the second held value and an inverse of the second held value; a first output switch connected between a first power source line and a power source output of the mode detector, wherein the first output switch is configured to be controlled by the output of the first latch; a second output switch connected between a second power source line and the power source output of the mode detector, wherein the second output switch is configured to be controlled by the output of the second latch; a first AND gate with a first input and a second input connected to the inverse output of the second latch, wherein the first input is configured to receive a first power on reset signal based upon the first power source line; and a second AND gate with a first input and a second input connected to the inverse output of the first latch, wherein the first input is configured to receive a second power on reset signal based upon the second power source line, wherein the mode of the circuit is indicated by the outputs of the first latch and the second latch.