System-Level ESD: Design: Summary

There are many design aspects that should be taken into account during the challenge of a functional and reliable product design. The trends towards portable system design, higher data rates, faster signal speed, lower power consumption and lower operation voltages combined with high level SoC and SoP integration trigger an elevating complexity of the required design solutions, substantially based on innovation and novel approaches.

The demand on new age electronics creates a significant design paradigm shift both in on-chip system-level design with integrated system-level ESD protection devices and off-chip PCB design with new Si TVS solutions that deliver both low parasitic capacitance and more accurate clamping voltage waveforms in comparison with outdated polymer or varistor type TVS components. The transient voltage suppression components are now designed to combine a more precise transient voltage waveform, appropriate dynamic characteristics with a record low parasitic capacitance of ~0.1 pF to support the board design.

At the same time the IC product pins interfacing with the system-level ports experience the secondary ESD current stress partly dissipated by TVS and PCB network. Often those pins are required to pass certain levels of system ESD test under power-on and power-off conditions in order to provide a predictable second stage current conduction. Thus those pins need to be protected for an order of magnitude higher current level than standard component specifications CDM, MM, and HBM.

In contrary to the trend of lowering component-level ESD target levels from 2 kV HBM below 500 V HBM, the severity of ESD stress in the real-user environment is much higher. It impacts the reliability of the consumer products directly unless a system-level protection is implemented.

ESD ''solutions'' for the system are no longer a simple choice of a suppressor component to place at the system port. An effective solution requires application of a new design methodology that takes into account the layout of the circuit board, the pulsed electrical characteristics of the suppressor and ESD characteristics of the IC itself.

System-level protection strategies for the ESD protection network design were already preliminary discussed in Sect. 1. They will be further elaborated across the remaining sections of this guide. They need to involve an understanding of the test methods and the correlation factors for the on-chip components (Sect. 2).

Engineering of the on-chip ESD protection devices (Sect. 3) and overall on-chip design including latch-up (Sect. 4) is an important part for the IC manufacturing and the IC specification. The off-chip and on-chip system-level co-design methodology (Sect. 5) becomes a logical step to address the expectation from the new era consumer, medical, automotive, industrial and other electronic applications.

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