Power Switch Circuit with Default Gate Voltage for Fast Source Switchover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power switch circuits are slow in responding to changes in power sources, leading to system shutdowns when external high-voltage power sources are plugged in, as they take too long to reach the threshold voltage for turning on the power switch, causing the output voltage to drop below safe levels.
Innovation Solution
A power switch circuit with a control circuit and a voltage holding circuit that includes a clamping circuit, current path circuit, and current source circuit to quickly maintain a control voltage greater than 0V, allowing the power switch to turn on more rapidly and prevent system shutdowns by providing a default voltage and increased current when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single charge pump is used to provide control voltage, then the device complexity is reduced, but the response speed becomes too slow causing system shutdown
Solution Approach 1:
The patent divides the charge pump function into two separate charge pumps (first charge pump and second charge pump) that operate at different stages. The first charge pump provides initial voltage boost from 0V to intermediate level, while the second charge pump provides additional voltage boost to reach the threshold voltage quickly. This segmentation allows each pump to be optimized for its specific function, achieving fast response without excessive complexity.
2Device complexity
If the control voltage starts from 0V, then the voltage holding circuit is simpler, but the time to reach threshold voltage causes output voltage to drop below safe levels
Solution Approach 1:
The voltage holding circuit maintains the control terminal voltage at a default value greater than 0V (specifically 3.3V) before the power switch needs to be turned on. This preliminary voltage level is held ready by the voltage holding circuit comprising capacitor and switch, so that when activation is needed, the control voltage only needs to increase from 3.3V to the threshold voltage, significantly reducing the time required compared to starting from 0V.
3Use of energy by moving object
If the control voltage increases slowly, then the charge pump current can be lower, but the output voltage drops below safe values causing system shutdown
Solution Approach 1:
The patent uses a two-stage periodic charging approach where the first charge pump operates first to provide initial voltage boost, then the second charge pump operates to provide the final voltage boost to reach threshold. This periodic, staged action allows the system to achieve fast voltage increase (improving reliability) while distributing the current demand over time and across two pumps rather than requiring one pump to deliver all the voltage increase in a single continuous high-current operation.
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
The solution effectively increases the response speed of the power switch circuit, preventing system shutdowns and ensuring stable operation by maintaining the output voltage above safe levels when switching to external power sources, even with high-voltage inputs.
Implementation Method 1
The voltage holding circuit includes a clamping circuit configured to provide the default voltage according to the control signal
Implementation Method 2
the power switch circuit provides a charge pump to increase the control voltage of the power switch from the default value to a threshold voltage that the power switch is turned on
Data Source
AI summary
A power switch circuit is disclosed. The power switch circuit includes an input terminal, an output terminal, a power switch, a control circuit and a voltage holding circuit. The power switch is coupled between the input terminal and the output terminal. The power switch has a control terminal. The control circuit is coupled to the input terminal and the output terminal respectively. The control circuit compares a first voltage of the input terminal with a second voltage of the output terminal to generate a control signal. The voltage holding circuit is coupled to the control circuit and the control terminal. The voltage holding circuit provides a default voltage larger than 0 V to the control terminal according to the control signal.