Over Voltage Protection Apparatus Discriminating EOS Events
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Solution Overview
Problem
Conventional over energy protection circuits fail to effectively distinguish between abnormal electrical over stress (EOS) events and normal system power ON/OFF events, leading to inadequate protection against abnormal energy discharges.
Innovation Solution
An over voltage/energy protection apparatus comprising a voltage detection circuit, a controlling circuit with a switch unit, an inverter circuit, and a clamp transistor, which detects over voltage events and generates control signals to manage the switch unit and inverter circuit to discharge abnormal energy from the power supply line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an R-C time constant based solution is used to discriminate abnormal energy events, then the circuit can distinguish normal system power ON/OFF events from ESD events, but it cannot detect EOS events that cause over high voltage rising
Solution Approach 1:
The patent changes the detection parameter from time-based (R-C time constant) to voltage-based (over high voltage threshold). The voltage detection circuit monitors the voltage level directly and triggers protection when the voltage exceeds a predetermined threshold, enabling detection of EOS events that cause rapid voltage spikes regardless of their duration
Solution Approach 2:
The protection function is segmented into separate detection and response components. The voltage detection circuit independently monitors voltage levels, while the clamp transistor independently executes protection actions. This segmentation allows the detection circuit to focus solely on voltage threshold detection without being constrained by time constant limitations
2Reliability
If the conventional circuit discharges abnormal energy, then protection against ESD events is achieved, but normal system power ON/OFF events are incorrectly treated as abnormal events
Solution Approach 1:
The patent changes the triggering parameter from time-based discrimination to voltage-level discrimination. By setting a predetermined voltage threshold that normal power ON/OFF events cannot exceed, the system accurately distinguishes between normal operation and abnormal EOS/ESD events, preventing false discharge while maintaining protection capability
Solution Approach 2:
The voltage detection circuit acts as an intermediary between the power supply line and the clamp transistor. It monitors the voltage level and only activates the clamp transistor when the voltage exceeds the predetermined threshold, serving as a selective gate that prevents false activation while enabling genuine protection
3Device complexity
If the R-C time constant circuit is used, then the circuit structure is simple, but it cannot detect rapid voltage rising in EOS events
Solution Approach 1:
The patent changes the fundamental detection parameter from time-constant-based to voltage-threshold-based detection. This simple parameter change enables the circuit to detect rapid voltage rising in EOS events without requiring complex timing circuits or multiple components, maintaining structural simplicity while dramatically improving detection capability
Solution Approach 2:
The patent replaces the mechanical/time-based R-C charging/discharging mechanism with a direct voltage threshold comparison mechanism. This substitution eliminates the limitations of time-constant-based detection while maintaining circuit simplicity, as the voltage detection circuit directly compares the instantaneous voltage level against the predetermined threshold
Data Source
AI summary
An EOS/ESD protection apparatus includes a voltage detection circuit, a controlling circuit having a switch unit, an inverter circuit, and a clamp transistor. The voltage detection circuit is configured to detect whether an over voltage event occurs in a power supply line to generate a switch control signal. The switch unit is turned on/off to generate a voltage control signal according to the switch control signal. The inverter circuit has an output and an input coupled to the voltage control signal transmitted from the controlling circuit. The clamp transistor has a control terminal coupled to the output of the inverter and is configured to be turned on when the over voltage event occurs in the power supply line.