Clock Circuit Power Switching with On-Chip Load Capacitors
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Solution Overview
Problem
Clock circuits, particularly real-time clocks, face challenges in flexibility with load capacitors and high power consumption in backup power supplies due to complex and inefficient switching schemes.
Innovation Solution
A system that automatically switches between a primary and auxiliary power supply for clock circuits using a voltage detector and switch circuitry, allowing for efficient power management and on-chip implementation of load capacitors to reduce component count and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a backup power supply is used to power the RTC, then the RTC can operate continuously, but power consumption increases due to complex switching schemes
Solution Approach 1:
The voltage detector automatically monitors the main power supply voltage and controls the switch circuit to select between main and backup power supplies without external intervention. The system self-regulates power source selection based on voltage thresholds, eliminating the need for complex external switching control while maintaining continuous RTC operation.
Solution Approach 2:
The voltage detector provides continuous feedback about the main power supply voltage status to the switch circuit. When the voltage drops below a threshold, the feedback signal triggers automatic switching to the backup power supply, ensuring continuous operation while minimizing unnecessary switching and power consumption.
2Manufacturing precision
If off-chip load capacitors are used, then the desired oscillation frequency can be achieved, but component count and board area increase
Solution Approach 1:
The load capacitors are integrated directly onto the clock circuit chip, merging what were previously separate off-chip components into the main circuit substrate. This integration maintains the required capacitance values for accurate oscillation frequency while reducing the total component count and eliminating the need for separate capacitor mounting on the PCB.
Solution Approach 2:
The clock circuit chip is designed to perform multiple functions including oscillation generation, load capacitance provision, and voltage detection. By incorporating load capacitors directly on-chip, the device becomes more universal and self-sufficient, eliminating the need for external passive components that were previously required.
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 provides flexibility in load capacitor values and reduces power consumption by automatically switching to an auxiliary power supply when the primary supply is insufficient, ensuring continuous operation of clock circuits with minimal power waste.
Implementation Method 1
a voltage detector to detect the primary power supply voltage and to generate a control signal based on the voltage
Implementation Method 2
a switch circuit coupled to receive the control signal and to couple either of the primary power supply or the auxiliary power supply to the clock circuit
Implementation Method 3
the oscillator of the analog portion of a real time clock is a crystal oscillator that uses load capacitors to generate a desired oscillation frequency
Data Source
AI summary
In one embodiment, a power supply switching circuit may automatically provide power to a clock circuit from one of an auxiliary power supply and a main power supply, based on a voltage of the main power supply. To provide automatic switching, a switch circuit coupled between the power supplies and the clock circuit may be controlled by a voltage detector, in some embodiments.