Electrostatic Protection Circuit With Dual Time Constant Control
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Solution Overview
Problem
Existing electrostatic discharge protection circuits face challenges in accurately initiating and terminating discharge operations, leading to potential damage from excessive voltage or mis-operation during power activation, especially when the rise time of the power supply voltage is steep or when power is activated.
Innovation Solution
An electrostatic protection circuit with a discharge circuit, latch circuit, switch circuit, and control circuit is designed to control the discharge operation based on steep voltage rises and set voltage thresholds, ensuring proper timing and preventing excessive discharge during power activation by using separate time constants for starting and stopping the discharge operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single time constant circuit is used to control discharge operation, then the circuit configuration is simple, but the discharge duration cannot be precisely controlled leading to either insufficient discharge or mistaken operation during power activation
Solution Approach 1:
The patent divides the single time constant control into two separate time constant circuits: a first time constant circuit (R1-C1) for controlling the start of discharge operation, and a second time constant circuit (R2-C2) for controlling the end of discharge operation. This segmentation allows independent optimization of discharge timing parameters, enabling precise control of discharge duration while maintaining circuit reliability during power activation.
Solution Approach 2:
The patent implements dynamic control of the discharge circuit by using two different time constants (τ1 = R1×C1 and τ2 = R2×C2) that operate at different stages of the discharge process. The first time constant controls the rapid response at discharge initiation, while the second time constant controls the gradual termination phase, creating a dynamically adaptive discharge profile that prevents both insufficient discharge and mistaken operation.
2Reliability
If the time constant is set for sufficient discharge duration, then electrostatic discharge is effectively released, but the circuit mistakenly operates when power supply voltage rises at power activation
Solution Approach 1:
The patent segments the time constant control into two distinct circuits with different parameters. The first time constant circuit (R1-C1) is configured with a smaller time constant to respond quickly to electrostatic discharge events, while the second time constant circuit (R2-C2) is configured with a larger time constant to control the discharge termination phase. This segmentation prevents mistaken operation during power activation by ensuring that only rapid voltage changes trigger discharge.
Solution Approach 2:
The patent applies different time constant characteristics to different functional stages of the discharge process. The first time constant circuit provides rapid response characteristics for discharge initiation, while the second time constant circuit provides slower, more controlled characteristics for discharge termination. This local differentiation of time constant quality enables the circuit to distinguish between electrostatic discharge events and normal power activation.
3Speed
If the time constant is set for rapid discharge response, then electrostatic discharge is quickly released, but the discharge operation duration is insufficient
Solution Approach 1:
The patent implements a two-phase dynamic discharge process using separate time constant circuits. The first time constant circuit (R1-C1) controls the initial rapid response phase with a smaller time constant, enabling quick discharge initiation. The second time constant circuit (R2-C2) controls the extended duration phase with a larger time constant, ensuring sufficient discharge completion. This dynamic two-stage approach achieves both rapid response and adequate duration.
Solution Approach 2:
The patent segments the discharge operation into two temporal phases controlled by different time constant circuits. The first phase (controlled by R1-C1) handles rapid voltage changes with a smaller time constant, while the second phase (controlled by R2-C2) maintains discharge operation with a larger time constant. This temporal segmentation resolves the contradiction between speed and duration by applying different time scales to different discharge phases.
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
This configuration allows for precise control of discharge operations, preventing damage from electrostatic discharges and ensuring a stable power supply voltage, thereby protecting internal circuits from excessive voltage and mis-operation.
Implementation Method 1
a first capacitor C1 connected between a third node N3 and another one out of the first and second nodes N2, a second capacitor C2 connected between a fourth node N4 and the other one out of the first and second nodes N2
Implementation Method 2
a first impedance element R1 connected between a third node N3 and one out of the first and second nodes N2, a second impedance element R2 connected between a fourth node N4 and the one out of the first and second nodes N2
Data Source
AI summary
This electrostatic protection circuit makes it possible for a discharge operation to be started only in the case where a rise in an applied voltage is steep, and for static electricity to be sufficiently released. This electrostatic protection circuit includes a discharge circuit that is connected between a first node and a second node and discharges charge produced by static electricity, a latch circuit that is connected between the first node and the second node and outputs a signal that controls operation of the discharge circuit to the discharge circuit, a switch circuit that is connected to the latch circuit and changes the signal that controls operation of the discharge circuit, and a control circuit that is connected between the first node and the second node and outputs a signal that controls operation of the switch circuit to the switch circuit.