Bandgap Reference Voltage Circuit With Capacitor-Hold Low-Power Control
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Solution Overview
Problem
Conventional reference voltage circuits for microcontroller units (MCUs) face challenges such as high power consumption, poor precision, and sensitivity to temperature and voltage variations, which affect the performance of power management circuits and battery life in low-power applications like intelligent water meters.
Innovation Solution
A reference voltage circuit incorporating a bandgap reference circuit, bias current generator, capacitors, comparator, and control logic circuit that automatically switches between active and low power modes based on voltage differences across capacitors, ensuring consistent reference voltage and minimizing power consumption by only activating the bandgap reference circuit when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the bandgap reference circuit is continuously activated to maintain high precision reference voltage, then the reference voltage precision is improved, but the power consumption increases
Solution Approach 1:
The bandgap reference circuit operates in periodic cycles, alternating between active mode (charging capacitors to maintain precision) and low power mode (discharging capacitors to save energy). The control logic circuit monitors voltage differences and triggers periodic recharging when thresholds are exceeded, achieving both precision and low power consumption.
Solution Approach 2:
The system uses its own stored energy in capacitors to maintain reference voltage during low power mode, and automatically recharges when voltage drift exceeds thresholds. The comparator and control logic create a self-regulating system that manages its own power consumption without external intervention.
2Use of energy by moving object
If the bandgap reference circuit is turned off to reduce power consumption, then the power consumption is reduced, but the reference voltage precision deteriorates
Solution Approach 1:
The capacitors are pre-charged to the reference voltage level during active mode before the bandgap circuit is turned off. This preliminary energy storage allows the system to maintain acceptable reference voltage levels during low power mode without immediate recharging, enabling extended low power operation while preserving precision within acceptable bounds.
3Use of energy by moving object
If the reference voltage circuit operates in low power mode with capacitors discharging, then the power consumption is reduced, but the voltage stability decreases
Solution Approach 1:
The comparator continuously monitors the voltage difference between capacitors and the reference voltage, providing feedback to the control logic circuit. When the voltage drift during discharging exceeds a predetermined threshold, the feedback signal triggers the bandgap reference circuit to reactivate and recharge the capacitors, restoring voltage stability while minimizing power consumption.
Data Source
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Figure 2B
AI summary
A reference voltage circuit is provided, which includes bandgap reference circuit, bias current generator, first capacitor, second capacitor, comparator and control logic circuit. In the active mode of the control logic circuit, the control logic circuit controls the bandgap reference circuit to deliver bandgap reference voltage. The comparator transmits first comparison signal to control logic circuit when the first and second capacitors are charged to the bandgap reference voltage. The control logic circuit enters low power mode and controls the bandgap reference circuit to stop delivering the bandgap reference voltage. If the comparator detects the potential difference between the first capacitor and second capacitor exceeds the threshold value, the control logic circuit returns to active mode according to the second comparison signal transmitted form the comparator.