Low Current DC-DC Converter With Integrated Coulomb Counter
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Solution Overview
Problem
Conventional DC-DC converters for battery-powered applications face challenges in achieving low quiescent current while accurately counting Coulombs, as continuous monitoring requires high operating current, leading to battery discharge and potential inaccuracies in Coulomb counting.
Innovation Solution
A power supply system with a regulator circuit and integrated Coulomb counter that operates in low quiescent current modes by enabling Coulomb counting only during specific time periods and using hysteretic control to minimize active circuits when not needed, allowing for accurate Coulomb measurement and accumulation with reduced quiescent current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If continuous monitoring of battery current is implemented in conventional Coulomb counters, then Coulomb counting accuracy is maintained, but quiescent current increases to 70μA-100μA which is unacceptably high for long lifetime battery applications
Solution Approach 1:
The patent implements periodic action by enabling the Coulomb counter to operate in discrete measurement modes rather than continuous monitoring. The counter activates only during specific time periods when measurement is required, allowing it to enter low-power states between measurements. This periodic operation dramatically reduces quiescent current while maintaining adequate counting accuracy through strategic sampling at key moments in the DC-DC converter operation cycle.
Solution Approach 2:
The patent applies dynamics by making the Coulomb counter's operational state variable - switching between active measurement mode and low-power standby mode based on operational requirements. The counter dynamically adjusts its monitoring intensity and activation timing to match the actual needs of the system, rather than maintaining constant high-current operation. This dynamic state transition enables the system to adapt power consumption to actual measurement needs.
2Use of energy by moving object
If the Coulomb counter is disabled to reduce quiescent current, then power consumption decreases, but significant discharge events may be missed and accuracy suffers greatly
Solution Approach 1:
The patent implements preliminary action by enabling the Coulomb counter during specific predetermined time periods before actual discharge events occur. By anticipating when discharge events are likely to happen based on the DC-DC converter's operational cycle, the system activates the counter in advance, ensuring no discharge events are missed while keeping the counter inactive during periods when discharge is unlikely, thus balancing accuracy with low power consumption.
Solution Approach 2:
The patent uses feedback mechanisms where the Coulomb counter's operation is controlled based on signals from the DC-DC converter's control circuit. The system monitors converter state and provides feedback to the Coulomb counter activation, enabling the counter only when the converter is in states where discharge events are occurring or about to occur. This feedback-based control ensures accurate capture of all discharge events while minimizing unnecessary counter operation and power consumption.
3Reliability
If DC-DC conversion operates continuously to maintain output voltage, then voltage regulation is maintained, but power consumption increases and battery life is reduced
Solution Approach 1:
The patent applies periodic action to DC-DC conversion by switching between active conversion mode and sleep mode based on load requirements and battery state. The converter operates periodically rather than continuously, activating only when voltage regulation is needed and entering low-power sleep mode when regulation is maintained or load is minimal. This periodic operation maintains voltage reliability while dramatically reducing average power consumption to extend battery life.
Solution Approach 2:
The patent implements dynamics by making the DC-DC converter's operational state adjustable and responsive to system conditions. The converter dynamically transitions between different power modes (active, standby, sleep) based on real-time monitoring of output voltage, load demands, and battery state. This dynamic operation allows the system to maintain voltage regulation reliability when needed while minimizing power consumption during light-load or stable-condition periods, optimizing overall battery life.
Data Source
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AI summary
A power supply system includes a regulator circuit responsive to an input signal at the input node (VIN) for producing an output signal at the output node (VOUT) at a desired level. The regulator circuit has a controller (12), an inductive element (L) and a first switch coupled to the inductor element (A) and controlled by the controller to produce the output signal. Also, the power supply system includes a Coulomb counter (22) for producing a Coulomb count signal proportional to the number of Coulombs passing from the input node to the output node. The Coulomb counter is enabled by an enabling signal representing a predetermined time period, for determining the number of Coulombs passing from the input node to the output node during that predetermined time period.