Input Circuit Reducing Dark Current via Mode-Switched Resistance
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Solution Overview
Problem
In battery systems, such as those used in vehicles, the continuous flow of current during low power or sleep modes can lead to the depletion of battery power over time due to 'dark current' when the system is idle for extended periods, resulting in battery weakening or complete discharge.
Innovation Solution
The implementation of input circuits with a pull-up or pull-down resistor configuration, a switch unit, and a dark current reduction unit that allows for different current paths in normal and low power modes, where the low power mode current path has higher resistance, reducing dark current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the system operates in low power mode with continuous current supply to maintain readiness, then system readiness is maintained, but battery power is depleted over time due to dark current
Solution Approach 1:
The input circuit dynamically switches between normal mode and low power mode based on system state. In normal mode, the switch unit connects the pull-up resistor to the battery for standard operation. In low power mode, the switch unit disconnects the battery while maintaining input signal functionality through the resistor network, thereby eliminating dark current while preserving system readiness capability.
Solution Approach 2:
The circuit changes the electrical resistance parameter of the input path based on operating mode. By using a pull-up resistor with specific resistance value (e.g., 10kΩ) and controlling the switch unit, the circuit presents different impedance characteristics to the input signal in normal versus low power mode, enabling dark current reduction while maintaining signal detection capability.
2Measurement precision
If the pull-up resistor is continuously connected to the battery in normal mode, then input signal detection is ensured, but dark current increases in low power mode
Solution Approach 1:
The input circuit is segmented into distinct functional sections: the pull-up resistor section for input signal conditioning, the switch unit for mode control, and the dark current reduction unit with parallel resistors. This segmentation allows independent optimization of each section - the pull-up resistor maintains signal detection capability while the switch unit and parallel resistor network eliminate dark current in low power mode.
Solution Approach 2:
The switch unit acts as an intermediary between the battery and the pull-up resistor network. It mediates the connection state based on operating mode, allowing the pull-up resistor to remain connected to the input terminal for signal detection while preventing direct battery connection that would cause dark current. The parallel resistor network serves as an intermediary path that maintains circuit functionality without drawing significant current.
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 effectively reduces dark current in low power modes by increasing the resistance of current paths, thereby minimizing battery drain during idle periods, ensuring the battery remains charged and maintaining system readiness.
Implementation Method 1
the dark current reduction unit enables a current path in the low power mode to have a higher resistance than a current path in the normal mode
Data Source
AI summary
Various embodiments include an input circuit comprising: a pull-up resistor having one end thereof connected to an input terminal; a switch unit for establishing/blocking a connection between the other end of the pull-up resistor and a battery; and a dark current reduction unit connected between the other end of the pull-up resistor and the switch unit, and enabling different current paths to be formed in a normal mode and in a low power mode. The dark current reduction unit enables a current path in the low power mode to have a higher resistance than a current path in the normal mode.