Overvoltage Protection Device Using Delayed Signal Switching
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Solution Overview
Problem
USB interface devices face challenges in overvoltage protection, leading to reduced lifespan and reliability due to voltage slew rates causing electromagnetic interference, and existing circuits struggle to maintain effective overvoltage protection while preventing long-term exposure to overvoltage.
Innovation Solution
An overvoltage protection device is designed with a first switch and a load providing circuit that delays data signals and increases input terminal impedance, preventing transient voltage increases and reducing electromagnetic interference by controlling the conduction of the first switch based on a delayed signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overvoltage protection circuit sustains overvoltage to protect the storage device, then the storage device can continue working, but the lifetime of the overvoltage protection circuit is greatly decreased
Solution Approach 1:
The patent applies preliminary action by proactively detecting overvoltage conditions before they cause damage and preemptively adjusting the output voltage. The control circuit monitors the voltage level and reduces it below the overvoltage threshold in advance, preventing the overvoltage protection circuit from needing to sustain damaging overvoltage conditions while still protecting the storage device from overvoltage damage.
2Speed
If the voltage slew rate is increased to improve response speed, then the voltage changes faster, but electromagnetic interference is easier to cause
Solution Approach 1:
The patent applies dynamics by implementing adaptive voltage slew rate control. The control circuit dynamically adjusts the rate of voltage change based on operating conditions, transitioning smoothly between voltage states rather than making abrupt changes. This dynamic control maintains fast response while limiting the maximum slew rate to reduce electromagnetic interference generation.
3Ease of operation
If the MOS transistor gate-source voltage is positive 2.145V to enable normal operation, then the transistor conducts properly, but the storage device only has average lifetime and reliability for about 1.68 years
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gate-source voltage of the MOS transistor based on the detected voltage conditions. When overvoltage is detected, the control circuit modifies the gate-source voltage parameter to reduce stress on the transistor, extending its operational life while maintaining adequate conduction for normal operation during standard voltage conditions.
Data Source
AI summary
An overvoltage protection device including an output stage, a first switch and a first load providing circuit is provided. The output stage has a first input terminal to receive a first signal, and generates an output signal at an output terminal of the output stage according to the first signal. A first terminal of the first switch is coupled to the first input terminal of the output stage, and a control terminal of the first switch receives a second signal. The first signal is the delayed second signal. The first load providing circuit is coupled to a second terminal of the first switch. The first load providing circuit provides an impedance to the first input terminal when the first switch is turned on.