DC-DC Converter Window-Mode Control for Ultra-Low Leakage
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Solution Overview
Problem
Conventional DC-DC converters in power management units of portable devices continue to draw static leakage current even in sleep modes, reducing the recharge and replacement cycle of batteries due to the inclusion of 'Always-ON' components like voltage regulators, comparators, and amplifiers.
Innovation Solution
A DC-DC converter with a capacitively-charged switched reference (SR) isolated during coasting periods and suspended operations of all circuits except the low-side-comparator, combined with the option to suspend the master reference generator, reduces static quiescent current by alternating between coasting and burst periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional DC-DC converters include voltage regulators with Always-ON references, comparators, amplifiers, buffers and drivers to regulate voltage rails, then voltage regulation accuracy is maintained in all modes, but static leakage current increases continuously
Solution Approach 1:
The patent implements dynamic operation of voltage regulator components by transitioning between active and suspended states based on operational mode. During active mode, all regulator components (references, comparators, amplifiers) operate continuously to maintain precise voltage regulation. During sleep mode, non-essential components are suspended while maintaining minimal monitoring capability, dramatically reducing static leakage current while preserving sufficient voltage regulation accuracy for wake-up circuits and sensors.
Solution Approach 2:
The patent employs periodic bursting operation where the DC-DC converter alternates between active periods (when voltage regulation is fully active) and sleep periods (when regulation is minimized). During sleep mode, the system periodically monitors voltage rails and activates full regulation only when voltage thresholds are breached, rather than maintaining continuous regulation. This periodic action reduces static current while maintaining adequate voltage accuracy through intermittent correction.
2Use of energy by moving object
If DC-DC converter components are suspended during sleep mode to reduce static leakage current, then power consumption decreases, but voltage regulation accuracy may deteriorate
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor voltage rail levels even during sleep mode when most regulator components are suspended. Low-side comparators and threshold detection circuits remain active to detect when voltage drops below minimum acceptable levels. When voltage regulation accuracy deteriorates below thresholds, feedback signals trigger activation of the full voltage regulator system to restore proper regulation, ensuring voltage accuracy is maintained through reactive correction rather than continuous operation.
Solution Approach 2:
The voltage regulation system performs self-service by automatically activating components only when needed. The suspended regulator monitors its own output voltage and self-activates when regulation accuracy deteriorates, eliminating the need for external control signals. This self-service approach maintains voltage regulation accuracy through demand-driven operation, activating full regulation capability only when the system detects degradation in voltage quality 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 extends the duration of coasting periods, significantly reducing power consumption and extending the battery life of portable devices by minimizing static leakage current during sleep modes.
Implementation Method 1
storing a low reference voltage (Vref_low) from a Vref_low generator to a local, capacitively-charged switched reference (SR)
Data Source
AI summary
A DC-DC converter and method of operating the same are provided to increase efficiency in window-mode. Generally, the method begins in a coasting-period with receiving in the converter a window-mode enable signal, and opening a switch through which a low reference voltage generator is coupled to a capacitively-charged switched reference (SR) on a first input of a low-side-comparator. Operation of all circuits and devices in the converter, except the comparator is suspended. The voltage on the SR is compared to a feedback voltage (vfb) coupled to a second input of the comparator from a regulated rail coupled to an output of the converter, to sense a change in the voltage on the regulated rail as it is discharged through a load coupled thereto. When vfb is less than the SR voltage, in a burst-period operation of circuits and devices is resumed, and the switch is closed to recharge the SR.