RC-Timed Clamping Circuit for Extended External Terminal ESD Protection
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Solution Overview
Problem
Existing clamping arrangements for internal voltage supply rails in semiconductor devices are inadequate to handle ESD events at external terminals, requiring larger footprints and longer durations than necessary, leading to potential damage from residual current pulses.
Innovation Solution
A clamping arrangement using an RC-timer and RC-interruption circuit, comprising a detector and switch, to extend the duration of protection by suspending the RC-timer, and a clamp circuit, which includes a clamp circuit, and a clamp circuit, to manage ESD events effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard clamping arrangement is used for internal voltage supply rail, then it provides basic ESD protection for short duration, but it cannot handle ESD events at external terminals requiring longer duration and higher current
Solution Approach 1:
The patent implements dynamic extension of protection duration by introducing a switch that responds to ESD detection signals. When an ESD event is detected at the external terminal, the switch closes to extend the RC-timer duration, allowing the clamping arrangement to adapt its protection duration dynamically based on the actual ESD event characteristics rather than using a fixed duration design
2Reliability
If a larger clamping circuit is designed to handle external terminal ESD events, then protection duration and current handling are improved, but the circuit footprint and capacity increase significantly
Solution Approach 1:
The patent makes the internal clamping arrangement multi-functional by enabling it to handle both internal supply rail ESD events and external terminal ESD events. Through the switch and ESD detection mechanism, the same compact clamping circuit serves dual purposes: protecting against normal internal ESD events with standard RC-timer operation, and protecting against external terminal ESD events with extended duration when the switch activates, thereby eliminating the need for separate larger protection circuits
3Duration of action of moving object
If the RC-timer duration is extended to handle external ESD events, then protection duration is improved, but the circuit complexity and current requirements increase
Solution Approach 1:
The patent introduces a switch as an intermediary component that mediates between the RC-timer and the rest of the circuit during ESD events. This switch acts as a controlled extension mechanism that only activates during detected ESD events, providing temporary duration extension without permanently increasing circuit complexity. The switch is controlled by ESD detection signals, creating a simple yet effective mechanism to extend protection duration only when needed
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 allows for a compact, low-capacity clamping circuit to protect internal circuits from ESD events, reducing the overall footprint and ensuring effective current dissipation without significant voltage increase, thus safeguarding semiconductor devices.
Implementation Method 1
a clamp circuit comprising an RC-timer, the clamp circuit arranged between an internal voltage supply rail and a second supply voltage supply rail and configured to, on detection of a high-voltage ESD event at an external terminal, protect a protected circuit from the ESD high-voltage for a duration defined by an RC-timer
Implementation Method 2
a detector connected to an input of the protected circuit and configured to detect that a voltage thereat is above a reference voltage
Implementation Method 3
a switch configured to, in response to the detector detecting that the voltage at the input to the protected circuit is above the reference voltage, provide a current path between a mid-node of the RC-timer and a one of the second voltage supply rail and the internal supply voltage supply rail
Data Source
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AI summary
Disclosed is a clamping arrangement, comprising: a clamp circuit, arranged between an internal supply voltage supply rail (Vcc) and a second supply voltage supply rail (Vss) and configured to, on detection of a high-voltage ESD event at an external terminal, protect a protected circuit from the ESD high-voltage for a duration defined by an RC-timer; and an RC-interruption circuit configured to suspend the operation of the RC-timer and thereby extend the duration, wherein the RC-interruption circuit comprises; a detector configured to detect that a voltage at an input to the protected circuit is above a reference voltage, and a switch configured to provide a current path between a mid-node of the RC-timer and a one of the second voltage supply rail and the internal supply voltage supply rail, in response to the detector detecting that the voltage at the input to the protected circuit is above the reference voltage.