Linear Regulator Mode Switching for Low Quiescent Current
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional linear regulators face challenges in reducing power consumption while maintaining output voltage stability, particularly in achieving accurate load current transition points and minimizing output voltage oscillations due to unstable mode transitions.
Innovation Solution
A linear regulator system with a mode selection circuit that adjusts between continuous power mode and duty cycle power save mode based on sampled load current and output voltage error signals, utilizing a slow loop for load current sampling and a fast loop for output voltage error detection, and incorporating analog floating gate technology to minimize noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional continuous-biased references are used in LDOs, then output voltage stability is maintained, but power consumption increases
Solution Approach 1:
The reference voltage circuit dynamically switches between continuous-biased mode and duty-cycled mode based on load conditions. The mode selection circuit monitors load current and transitions the reference circuit between operational states, enabling the system to adapt power consumption to actual performance requirements rather than operating continuously at fixed bias
Solution Approach 2:
The invention changes the operational parameters of the reference voltage circuit by switching between continuous biasing and duty-cycled biasing. This parameter change allows the circuit to achieve ultra-low quiescent current (below 1 nA) in light-load conditions while maintaining adequate output voltage regulation through the dual-loop control mechanism
2Use of energy by stationary object
If duty cycle power save mode is used to reduce power consumption, then quiescent current decreases, but response speed to load changes slows down
Solution Approach 1:
The fast transient response loop provides immediate feedback when output voltage deviations are detected, regardless of the reference circuit's operational mode. This feedback mechanism detects voltage errors and triggers mode transitions or corrective actions, ensuring rapid response to load changes even when the reference circuit operates in ultra-low power duty-cycled mode
Solution Approach 2:
The system applies partial action by using duty-cycled biasing only for the reference voltage circuit while keeping other critical components (such as the error amplifier and fast transient detection circuitry) continuously operational. This selective partial operation achieves power savings without compromising overall system response speed
3Use of energy by stationary object
If mode transition point is set for low power operation, then power savings increase, but accuracy of load current detection decreases
Solution Approach 1:
The mode selection circuit acts as an intermediary that accurately monitors load current and determines the appropriate operational mode. This intermediary circuit uses precise threshold detection to identify when load current crosses transition points, enabling accurate mode selection without requiring the reference circuit itself to continuously operate at high precision
Solution Approach 2:
The system performs preliminary action by pre-establishing accurate mode transition thresholds and hysteresis bands before mode switching occurs. This preliminary configuration ensures that mode transitions happen at the correct load current points with minimal toggling, maintaining detection accuracy while enabling aggressive power savings
4Stability of the object's composition
If DC hysteresis is increased between modes, then mode transition stability improves, but accuracy of load current measurement decreases
Solution Approach 1:
The mode selection circuit segments the load current range into distinct operational zones with defined transition thresholds. By segmenting the operation into clear regions (ultra-low power mode, medium power mode, high power mode) with specific transition points, the system achieves stable mode transitions without requiring excessive hysteresis that would degrade measurement accuracy
Data Source
AI summary
A system includes an input voltage source, a linear regulator coupled to the input voltage source, and a load coupled to an output of the linear regulator. The linear regulator includes an error amplifier coupled to a control terminal of a switch; and a control circuit coupled to the error amplifier and configured to provide a reference voltage to the error amplifier. The control circuit includes a mode selection circuit with a slow loop configured to sample a load current and with a fast loop configured to detect an output voltage error signal. The mode selection circuit is configured to adjust a mode of the control circuit between a continuous power mode and a duty cycle power save mode based on the sampled load current and the output voltage error signal.