Before diving into the day’s tasks, I often skim through my emails and notice recurring themes like quotes, project updates, and various requirements. One request that always catches my attention is the mention of “ESD†and “help.†This particular request came at a challenging moment, but it also presented a fantastic opportunity for manufacturers specializing in ESD protection solutions.
Electrostatic discharge (ESD) occurs when electrically insulating materials build up charge through friction. When a person carrying this charge touches a grounded metal object, a sudden discharge happens. This discharge can reach up to 30 kV, with a duration as brief as 100 nanoseconds and peak currents of up to 100 A. Most of us have experienced ESD in some form—like getting a small shock when touching a doorknob after walking indoors. While this might seem harmless or even amusing due to the tiny blue sparks, imagine if something similar happened while exiting your car and leaning on its body. Such incidents could affect the electronics inside your vehicle, potentially damaging sensitive components like those used in navigation systems.
Take GPS transceiver circuits, for instance. These systems play a crucial role in modern vehicles by helping them determine locations and connect to auxiliary systems. A typical GPS transceiver consists of an integrated circuit (IC) along with RF front-end components like transformers and surface-mount capacitors and resistors. Modern transceiver chips are becoming more compact and feature-rich thanks to advancements in semiconductor manufacturing processes. However, smaller geometries make these chips more susceptible to ESD, increasing the risk of damage during high-energy discharges.
In one case, a client had to replace their GPS transceiver IC in a later version of their Telematics Box because the original design failed to meet the ISO 10605 ESD standard at 8kV. Even though they managed to pass the lower 4kV threshold, this still posed risks for field failures, prompting the need for OEM exemptions.
To diagnose the issue, engineers first examined the schematics and PCB layouts. Once everything seemed correct, the focus shifted toward evaluating the actual modules. ON Semiconductor employs a technique called Transmission Line Pulse (TLP) testing to assess the characteristics of ESD pulses. Unlike traditional methods involving impedance mismatches, TLP operates in a controlled 50-ohm environment, enabling clearer observation of the clamping voltage of tested devices.
Following TLP tests on this specific module, it became evident that the internal ESD clamp structure of the new GPS transceiver had very low turn-on and clamping voltages. Given that many such devices rely on Zener diodes with breakdown voltages between 7 and 10 volts, adding external low-parasitic-capacitance ESD protection proved challenging. At these voltage levels, most transient currents flowed into the internal ESD structures of the GPS transceiver, which couldn’t handle higher energy pulses effectively.
Enter the SZESD9101P2T5G ESD protection device, part of ON Semiconductor’s innovative ESD9000 series. Utilizing an integrated thyristor rectifier (SCR) ESD clamp structure, this device turns on at the same 7-volt threshold but achieves much lower clamping voltages—around 2 to 3 volts—within just 3 nanoseconds. This rapid response ensures that ESD pulses are safely diverted to ground without harming the GPS transceiver IC. Initial tests showed promising results, with the SZESD9101 successfully protecting against 8kV pulses.
With the recommended ESD protection solution in place, TLP results confirmed compliance with the necessary standards, mitigating potential field failures. Providing deep technical insights and troubleshooting expertise is key to advancing ESD protection technologies. Solving complex challenges like these not only benefits our industry but also ensures safer roads for everyone. Each day brings new opportunities to address issues like these—one module at a time.
For further details about the SZESD9101 product, visit [link].
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