Adaptive Voltage Regulator Circuit for RTC Power
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Solution Overview
Problem
Existing power management systems for battery-powered devices, particularly those using CMOS Power Management ICs, are inefficient when dealing with low-voltage alkaline batteries and higher voltage Lithium-ion batteries, as they require inefficient step-up power converters to supply low-current RTC circuits, leading to high power consumption.
Innovation Solution
A versatile voltage regulator circuit that includes a low-drop-out (LDO) voltage regulator and a charge pump in a feedback loop, which adapts to the type of main battery used, employing a MOS switch transistor and error amplifier to efficiently regulate voltage and charge a back-up battery, optimizing power conversion for both low and high voltage batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a step-up power converter is used to supply low-voltage alkaline batteries to RTC circuits, then the RTC circuit can be powered, but power consumption increases significantly
Solution Approach 1:
The circuit dynamically switches between two operating modes: LDO mode for high-voltage batteries (3.0V Li-ion) and charge pump mode for low-voltage batteries (1.8-3.0V Alkaline). This dynamic adaptation allows the system to use the most efficient power conversion method for each battery type, resolving the contradiction between battery compatibility and power consumption.
Solution Approach 2:
The circuit changes its operational parameters based on input voltage levels. When VBAT exceeds a threshold (indicating Li-ion battery), the LDO regulator is enabled and charge pump is disabled. When VBAT is below the threshold (indicating Alkaline battery), the charge pump is enabled to step up the voltage. This parameter-based switching resolves the contradiction by optimizing power consumption for each battery type.
2Power
If a regulated charge pump is used to provide higher output voltage, then low-voltage alkaline batteries can power the RTC circuit, but the circuit requires tens of microamps current
Solution Approach 1:
The LDO voltage regulator serves as an intermediary that conditions the input voltage from high-voltage Li-ion batteries before it reaches the charge pump. This intermediary stage ensures the charge pump receives optimal input voltage, improving its efficiency and reducing current consumption when operating in charge pump mode.
Solution Approach 2:
The circuit integrates both LDO regulator and charge pump in a single universal power management IC that can handle both high-voltage and low-voltage batteries. This multi-functional design eliminates the need for separate regulation circuits for different battery types, reducing overall current consumption while maintaining the ability to provide required output voltage.
3Use of energy by moving object
If separate regulation circuits are used for different battery types, then each battery can be optimized, but device complexity increases
Solution Approach 1:
The LDO regulator and charge pump are merged into a single integrated power management circuit with unified control logic. The control circuit automatically detects battery type and switches between LDO and charge pump modes, combining the benefits of battery-specific optimization into one device without requiring separate regulation circuits, thus maintaining low complexity while achieving high power efficiency.
Solution Approach 2:
The circuit uses voltage detection feedback to automatically determine battery type and switch between operating modes. The control logic monitors VBAT voltage and activates the appropriate regulator (LDO for high voltage, charge pump for low voltage), providing automatic adaptation without complex external circuitry. This feedback mechanism resolves the contradiction by achieving battery-specific optimization through a single unified circuit.
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 solution provides efficient power conversion with low power consumption, capable of supplying low-current RTC circuits and charging back-up batteries, improving power efficiency and adaptability across various battery types, reducing the need for additional regulation circuitry.
Implementation Method 1
a regulated charge pump uses digital and analog circuits that require currents of at least some tens of microamps
Implementation Method 2
A low-drop-out (LDO) voltage regulator and a charge pump in a feedback loop, which adapts to the type of main battery used
Implementation Method 3
employing a MOS switch transistor and error amplifier to efficiently regulate voltage
Implementation Method 4
employing a MOS switch transistor and error amplifier to efficiently regulate voltage
Implementation Method 5
a 3 volt Lithium-Ion back-up battery ensures that the RTC circuit can operate for a relatively long time without a main supply battery
Data Source
AI summary
A versatile voltage regulator accommodates either an Alkaline or Lithium-Ion battery main battery and provides low-current power for a real time clock module and for charging a backup battery. Depending upon the battery power source that is used, the present invention provides a best circuit configuration for efficient power conversion. If the power converter according to the present invention provides a regulated output voltage that is greater than the main battery voltage of an Alkaline battery, a low drop-out-voltage (LDO) voltage regulator is used in feedback loop with a charge pump. Otherwise, for a Lithium-Ion battery, only a LDO voltage regulator is used. The voltage regulator includes a series low drop-out-voltage (LDO) voltage regulator that is coupled between the main external battery and the vout load terminal, when the voltage at the vout load terminal is less than the voltage of the main external battery. The voltage regulator also includes a charge pump circuit adapted to be connected in feedback loop with the LDO regulator and the vout load terminal, when the voltage at the vout load terminal exceeds the voltage of the main external battery.