Not all ESD specs cover the IEC ESD strike zone: Look for high IEC61000-4-2 coverage


Summer is here, and with it comes some inevitable things… like baseball and the occasional summer thunderstorm. Who doesn’t love to take in a ball game and see the pitcher strike out a powerful hitter?  Strikes can be good in baseball, but lightning strikes that come with summer storms can be destructive, much as high ESD strikes during installation or maintenance can be damaging to expensive electronic equipment. When it comes to designing systems for an industrial network, mitigating the risk of damage due to ESD strikes can prevent equipment failure and network downtime, and the RS-485 transceiver is often the first line of defense against these potentially costly ESD strikes.

IEC 61000-4-2 is the standard for testing system level robustness to ESD strikes. TI’s new SN65HVD147x family of full-duplex RS-485 transceivers have the industry’s highest level of IEC 61000-4-2 contact discharge protection at +16kV, giving designers unparalleled insurance that their system will survive and continue to operate as expected after a strike. Other ESD models, such as charged device model (CDM) and human body model (HBM), were developed to test electronic components’ susceptibility in the manufacturing process, but do not capture the potential high-voltage surge and high peak current that systems can be exposed to once in the field.

The IEC 61000-4-2 test, often designated as the gold standard for ESD testing, has typically eight times higher testing voltage than CDM, and twenty 20 times higher peak current testing than HBM.

Figure 1:  Comparison between ESD device and system level testing

 This comparison of ESD models in Figure 1 would indicate that the HBM ESD protection for our SN65HVD147x RS-485 transceiver family would be extremely high, and our testing has proven it to be the case as well! The SN65HVD147x family (+16kV IEC61000-4-2 contact discharge), as well as our SN65HVD7x family (+12kV IEC 61000-4-2 contact discharge), both pass our HBM ESD testing at +30kV. In fact, our ability to test these RS-485 transceiver families beyond +30kVHBM ESD is limited only by our test equipment! Powerful.

 While ESD models like HBM can show big numbers in terms of ESD protection, the rising demands of system level testing mean IEC61000-4-2 will provide the best indication that your design has the highest ESD protection. For your system design, make sure to choose an RS-485 transceiver that can step up to the plate and protect the IEC61000-4-2 strike zone.

For more information:

Learn more about TI’s industry-leading SN65HVD147x full-duplex RS-485 transceivers with +16kV IEC 61000-4-2 contact discharge at www.ti.com/RS485.

ESD protection is an important factor in system design. Another important element of protection for your system is digital isolation. Check out TI’s digital isolation portfolio, including our ISO7142CC, at www.ti.com/iso

  • It's nice to have ESD protection at higher voltage levels but you often have system problems at lower level discharges due to faster rise times. Resets and disruption seemed more common at lower levels of ESD in the systems I tested.