DPI Circuit Suppresses Noise in ESD Protection
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Solution Overview
Problem
Low-side drivers and transceiver pins in large systems, such as automobiles, face noise interference from wiring harnesses, leading to cumulative effects from repeated smaller voltage transients that can cause partial turn-on and interfere with normal operations during electrostatic discharge (ESD) events.
Innovation Solution
A direct power injection (DPI) circuit is designed to distinguish between extreme ESD events and milder noise events, using a charge-pump-like circuit capacitively coupled to the protected pin, which tunes the output to respond only to periodic stimuli, thereby preventing activation of ESD power devices during noise conditions by lowering impedance to ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ESD structures are designed to be activated by very high speed voltage transients, then ESD protection capability is improved, but noise events with smaller transients can have cumulative effects causing partial turn-on and interfering with normal operations
Solution Approach 1:
The patent implements a dynamic response mechanism where the ESD circuit's activation threshold and response characteristics change based on the duration and repetition of voltage transients. The circuit transitions from a static threshold-based activation to a dynamic state where repeated noise events accumulate charge slowly while extreme ESD events trigger rapid discharge, effectively distinguishing between transient noise and genuine ESD threats
Solution Approach 2:
The patent modifies the activation parameters of the ESD circuit by introducing a time-dependent charge accumulation mechanism. The gate voltage threshold for ESD activation is effectively changed from a fixed value to a dynamic value that depends on the duration and repetition frequency of input transients, allowing the circuit to adapt its sensitivity based on the nature of the voltage events
2Object-affected harmful factors
If the ESD power device is activated by noise transients, then noise suppression might occur, but normal operations are interfered with and ESD device activation during noise conditions causes interference
Solution Approach 1:
The patent implements a preliminary charge accumulation phase before ESD device activation. Rather than directly activating the ESD power device upon detecting any voltage transient, the circuit first accumulates charge on a gate capacitor through a controlled charging path. This preliminary action ensures that only sustained or repeated transients (noise) can slowly charge the capacitor, while extreme ESD events rapidly charge it to the activation threshold without causing premature ESD device turn-on
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 DPI circuit effectively suppresses noise effects on ESD circuits, ensuring that ESD devices are not activated by noise, thereby maintaining normal operations and preventing interference during ESD events.
Implementation Method 1
The design includes a small charge-pump-like circuit that is capacitively coupled to the pin being protected
Implementation Method 2
a complementary metal oxide silicon (CMOS) power device that is coupled to carry an electrostatic discharge (ESD) event on the protected pin to ground when turned ON
Data Source
AI summary
A DPI circuit reduces noise effects in an ESD circuit when coupled between an ESD circuit and a protected pin. The DPI circuit includes an NMOS transistor coupled between an output node and a lower rail and a charge pump coupled between the input node and the gate of the first NMOS transistor. A resistor is coupled between the gate of the first NMOS transistor and the lower rail.