Microcontroller Analog Circuit Capacitor Charge Maintenance
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Solution Overview
Problem
Microcontrollers with analog circuitry face a significant delay in powering up after entering low power sleep mode, leading to undesirable downtime and increased power consumption during this period, as the analog circuitry takes longer to stabilize compared to digital circuitry.
Innovation Solution
Incorporating a capacitor with large capacitance and a switch in series, where the switch is conductive during nominal power mode and nonconductive during low power sleep mode to store charge, allowing for quicker recharging and reducing the 'wake up' time when transitioning back to nominal power mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the microcontroller enters low power sleep mode to reduce power consumption, then power consumption is reduced, but the analog circuitry takes a relatively long time to power up and become operational
Solution Approach 1:
The capacitor is pre-charged to an intermediate voltage level before the microcontroller enters sleep mode. This preliminary charging action allows the analog circuitry to reach operational voltage faster upon waking, reducing the power-up delay while maintaining low power consumption during sleep mode.
Solution Approach 2:
The invention changes the voltage parameter of the capacitor from fully charged to an intermediate voltage level during sleep mode. By maintaining the capacitor at this intermediate voltage rather than fully charging it, the system achieves a balance between reducing power consumption and enabling faster analog circuitry operation upon waking.
2Loss of time
If the capacitor is fully charged during sleep mode to reduce wake-up time, then power up time is reduced, but power consumption during sleep mode increases
Solution Approach 1:
The invention optimizes the capacitor voltage parameter by maintaining it at an intermediate level rather than fully charging it during sleep mode. This parameter optimization reduces wake-up time sufficiently while minimizing the power consumption during sleep mode, achieving the best balance between these two competing requirements.
Solution Approach 2:
Instead of fully charging the capacitor during sleep mode (excessive action), the invention applies partial charging to reach an intermediate voltage level. This partial action is sufficient to reduce wake-up time while avoiding the excessive power consumption that would result from full charging during sleep mode.
3Reliability
If the switch remains conductive during sleep mode to maintain capacitor charge, then the capacitor voltage is maintained, but the analog circuitry continues to consume power
Solution Approach 1:
The invention extracts the capacitor from the analog circuitry by opening the switch during sleep mode. This separation allows the capacitor to be maintained at an intermediate voltage without drawing power from the analog circuitry, while still being available to quickly charge the analog circuitry upon waking.
Solution Approach 2:
The switch dynamically changes state based on the operational mode: conductive during active mode to allow capacitor charging and non-conductive during sleep mode to isolate the capacitor. This dynamic behavior enables the system to maintain capacitor voltage reliability while minimizing power consumption during sleep mode.
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 approach reduces the time required for the analog circuit to become operational after waking up from low power sleep mode, minimizing downtime and power consumption by maintaining a nonzero voltage on the capacitor, thus enabling faster analog signal processing.
Implementation Method 1
the capacitor of the analog circuit is switched out of the analog circuit when the analog circuit is transitioned from the nominal power mode to the low power sleep mode so that the capacitor maintains a nonzero voltage during the low power sleep mode
Implementation Method 2
a switch is provided in series with the capacitor. The electrical characteristics (for example, the switch on-resistance) of the switch are such that the presence of the switch in series with the capacitor does not prevent the analog circuit from operating satisfactorily
Data Source
AI summary
An analog circuit of a microcontroller includes a switch that is coupled in series with a capacitor of the analog circuit. During nominal power mode operation, an operational voltage is present on the capacitor. The switch is conductive so that the capacitor is switched into the analog circuit and so that the capacitor operates as part of the analog circuit. At the beginning of sleep mode operation, the switch is made nonconductive thereby effectively switching the capacitor out of the analog circuit and storing the operational voltage on the capacitor. When the analog circuit is powered up again after sleep mode operation, the switch is made conductive to switch the capacitor back into the analog circuit. Because the capacitor still holds a substantial voltage, analog circuit wake up time is reduced because the time required to charge the capacitor up to its operational voltage is reduced.