Power Supply Source Selection Circuit for Portable Devices
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Solution Overview
Problem
Portable devices face challenges in extending battery lifetime due to the need for efficient power source switching between internal batteries and external power supplies, which is complex and not easily implemented in monolithic device circuits.
Innovation Solution
A power supply source selection circuit incorporating a comparator and a switch that compares reference voltages derived from the battery and external supply to selectively choose between power sources, ensuring the selection of the most available and efficient power source, with the switch signal determining which voltage to use for a regulator output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If power supply source switching functions are implemented in monolithic device circuits, then device integration is improved, but circuit complexity increases
Solution Approach 1:
The patent combines the power supply source switching function with the existing voltage regulator into a single monolithic integrated circuit. The comparator, switch, and regulator are merged into one device, allowing the power management functionality to be directly integrated into the portable device without requiring separate discrete components, thus improving device integration while managing circuit complexity through functional consolidation.
2Duration of action of moving object
If external power supply is used to source power, then battery lifetime is extended, but power supply selection complexity increases
Solution Approach 1:
The integrated power supply source selection circuit automatically monitors the availability of external power supplies and autonomously switches between battery and external power sources without requiring manual intervention or complex control logic from the device user. The comparator continuously compares voltage levels and the switch automatically selects the appropriate power source, enabling the system to self-manage power supply selection while extending battery lifetime through intelligent external power utilization.
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 solution simplifies power source switching, optimizing battery lifetime by utilizing external power when available, ensuring efficient power distribution within the device and maintaining a stable output voltage, thereby extending battery life.
Implementation Method 1
The comparator has an input to accept a first reference voltage directly proportional to a bandgap reference voltage... The comparator has an input to accept a second reference voltage directly proportional to a first supply voltage... and an output to supply a switch signal in response to comparing the second reference voltage to the first reference voltage
Data Source
AI summary
A power supply source selection circuit is provided with a comparator and a switch. The comparator has an input to accept a first reference voltage directly proportional to a bandgap reference voltage. For example, the bandgap voltage may be derived from a battery voltage. The comparator has an input to accept a second reference voltage directly proportional to a first supply voltage (e.g., a line voltage), and an output to supply a switch signal in response to comparing the second reference voltage to the first reference voltage. The switch has an input to accept the first supply voltage, an input to accept a second supply voltage, and input to accept the switch signal. The switch has an output to supply a third supply voltage to a regulator. The third voltage has a voltage potential less than or equal to a maximum voltage value. The switch selects between the first supply voltage and the second supply voltage in response to the switch signal.