Bootstrap Power Supply Control for Light-Load Reverse Current
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Solution Overview
Problem
Existing switching power supply devices face inefficiencies in managing power supply control, particularly in maintaining stable output voltage during light load conditions and reducing power consumption, due to the limitations of conventional bootstrap circuits and reverse current detection.
Innovation Solution
The implementation of a power supply control device that includes a switching control circuit with a PWM circuit, logic circuit, high-side and low-side drivers, reverse current detection, and a monitor circuit, along with a bootstrap circuit using a boot capacitor and diode, to manage efficient switching and voltage regulation, especially during light load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If switching control is continuously performed to maintain output voltage, then output voltage stability is improved, but power consumption increases during light load conditions
Solution Approach 1:
The control circuit performs switching control intermittently rather than continuously by detecting light load conditions and stopping switching operations during these periods. This periodic action reduces power consumption while maintaining output voltage stability through adaptive control - switching control is activated when load increases and stopped when load decreases, creating a responsive on-demand operation pattern
2Device complexity
If bootstrap circuit is used to generate high-side driver power supply, then device complexity is reduced, but reverse current causes inefficiency and instability
Solution Approach 1:
The patent extracts the reverse current issue from the bootstrap circuit by adding a dedicated reverse current detection function. The control circuit now separately detects reverse current conditions and responds by stopping switching control, thereby removing the harmful effect of reverse current while preserving the simplicity of the bootstrap circuit structure
Solution Approach 2:
The control circuit implements feedback by continuously monitoring for reverse current conditions and adjusting switching control accordingly. When reverse current is detected, the control circuit stops switching operations, creating a closed-loop system that prevents energy loss while maintaining efficient operation during normal conditions
3Use of energy by moving object
If switching control is stopped during light load, then power consumption is reduced, but output voltage stability may deteriorate
Solution Approach 1:
The control circuit dynamically adapts switching control based on real-time load conditions. It transitions between active switching control and stopped switching control modes by detecting light load states, creating a dynamic system that optimizes power consumption while maintaining voltage stability through condition-responsive operation rather than fixed behavior
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
Enhances efficiency by intermittently stopping switching control during light loads, reducing power consumption, and maintaining stable output voltage through adaptive operation modes and reverse current detection, thereby improving overall performance and energy efficiency.
Implementation Method 1
a boot capacitor configured to charge to a voltage higher than a power supply voltage when a switching element is in an off state
Implementation Method 2
a diode connected in parallel with the boot capacitor
Implementation Method 3
a reverse current detection circuit configured to detect reverse current that flows when the switching element is in an on state
Data Source
AI summary
A power supply control device includes: an output stage circuit having a high-side transistor provided between an application terminal of an input voltage and a switch terminal, and a low-side transistor provided between the switch terminal and a ground terminal; a high-side driver; a low-side driver; a switching control circuit for controlling on/off state of the high-side and low-side transistors using the low-side and high-side drivers; a boot terminal for applying a boot voltage; a rectifying element for supplying a charging current to a boot capacitor during an on period of the low-side transistor; a reverse current detection circuit for detecting a specific reverse current state in which a reverse current flows from an output terminal to which the output voltage is applied, toward the low-side transistor via the coil and the switch terminal; and a monitor circuit for monitoring a height of the boot voltage.