Switching and Linear Regulator Control Circuit for Power Efficiency
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Solution Overview
Problem
In electronic devices with microcomputers, synchronous rectification type switching regulators waste power when load current is low due to reversed current flow, leading to inefficiency, and existing solutions do not adequately minimize power consumption during light load states.
Innovation Solution
A control circuit that switches between a step down switching regulator and a linear regulator based on load conditions, using a compulsory OFF circuit to prevent reverse current flow and a selector circuit to determine when to halt the switching regulator, ensuring stable output voltage by limiting the ON time of switching transistors and switching between regulators based on error voltage and current thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a synchronous rectification type switching regulator is used to miniaturize circuit area, then integration is possible inside LSI and circuit area is reduced, but when load current is small, efficiency becomes inferior compared to diode rectifier type
Solution Approach 1:
The patent dynamically switches between synchronous rectification type and diode rectifier type based on load current magnitude. The switching regulator control circuit changes the rectification method according to operating conditions, allowing the system to optimize between area efficiency and power consumption efficiency in different load states.
Solution Approach 2:
The patent changes the rectification mode parameter based on load current threshold. When load current exceeds the threshold, synchronous rectification is used for miniaturization; when it falls below, diode rectification is activated for efficiency, thus adapting the system parameter to operating conditions.
2Area of stationary object
If synchronous rectifier transistor is used instead of diode, then circuit area can be miniaturized for integration, but when load is light, current flows from inductor via synchronous rectifier transistor to ground causing unnecessary power consumption
Solution Approach 1:
The patent dynamically controls the synchronous rectifier transistor's operation state based on inductor current direction detection. When reverse current is detected, the circuit switches to diode rectification mode, preventing ground current flow and unnecessary power consumption while maintaining miniaturization benefits during normal operation.
Solution Approach 2:
The patent uses feedback control by monitoring inductor current direction to determine when to switch rectification modes. The switching regulator control circuit detects reverse current conditions and activates diode rectification accordingly, creating a closed-loop system that prevents power waste.
3Use of energy by moving object
If switching regulator is used to step down battery voltage, then power consumption is reduced compared to direct supply, but during light load states, reverse current flow causes inefficiency
Solution Approach 1:
The patent dynamically adjusts the rectification method within the switching regulator based on load conditions. During light load states when reverse current occurs, it switches to diode rectification to eliminate power wastage, while maintaining switching regulation for overall power consumption reduction during normal operation.
Solution Approach 2:
The patent changes the rectification parameter (synchronous vs. diode) based on load current magnitude, optimizing the balance between power consumption reduction and power wastage prevention across different operating conditions.
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 solution reduces power consumption by efficiently switching between regulators, minimizing power wastage during light load states and ensuring stable voltage supply by preventing reverse current flow and optimizing regulator usage based on load conditions.
Implementation Method 1
a pulse width modulator for generating a pulse width modulation signal with which a duty ratio is controlled so that output voltage of the switching regulator output circuit approaches a predetermined reference voltage
Implementation Method 2
a switching regulator output circuit, including an output capacitor and an inductor
Implementation Method 3
a switching regulator output circuit, including an output capacitor and an inductor
Data Source
AI summary
A control circuit is provided in which two power sources can be efficiently switched, for a power supply apparatus provided with a step down switching regulator and a linear regulator. A PWM controller generates a pulse width modulation signal with which a duty ratio is controlled so that output voltage of the switching regulator approaches a predetermined reference voltage. A compulsory OFF circuit monitors a switching voltage, and when a first threshold voltage is exceeded, switches a synchronous rectifier transistor OFF. A minimum ON time setting circuit limits the duty ratio of the pulse width modulation signal, so that ON time of the switching transistor is longer than a predetermined minimum value. A selector circuit monitors an error voltage, and when a predetermined state continues for a predetermined first period, puts the linear regulator in an operating state, and the step down switching regulator in a halt state.