Reducing Clamping Voltage

In part one, we learned transient voltage suppressor (TVS) clamping voltage is a key protection parameter. TVS manufacturers are constantly working to lower clamping voltage to keep up with ever shrinking IC geometries and increased sensitivity to overvoltage events. One method to achieve lower clamping is to engineer the device to “snapback” to a lower voltage once triggered. The snapback can be shallow, or deep depending on the intended application. One method of achieving a deep snapback is to design a self-triggering thyristor TVS structure (Figure 4).

I cannot tell you how many times I have heard this in reference to silicon-based Transient Voltage Suppressors (TVS). In all fairness, TVS manufacturers have probably perpetuated this notion. After all, we usually refer to these devices as TVS diodes or electrostatic discharge (ESD) protection diodes. Technically, a diode is a two terminal device that conducts current primarily in one direction. A TVS, or TVS diode, is a two terminal device that is designed to conduct current in the reverse breakdown region. However, calling it “just a diode” implies any TVS diode, or any diode type for that matter, can be effortlessly chosen and relied upon to protect your circuit. Following this assumption will most likely lead to disappointing results.

Ethernet ports are exposed to external transient events in the form of electrostatic discharge (ESD), electrical fast transient (EFT), lightning, and cable discharge events (CDE). External transient voltage suppressor (TVS) diodes are commonly used to protect the Ethernet PHY chips from these threats. However, we find that a lot of confusion exists on how to best connect the TVS diode for maximum effectiveness. Common wisdom would suggest connecting the diode near the RJ-45 connector, from each signal line to ground. In actuality, the TVS should be connected across the signal pair and located on the PHY side of the connector. In this blog, we will examine why.

Gateways featuring Semtech’s LoRa® devices often reside in electrically harsh industrial environments. As the centerpiece for a LoRaWAN® network, these gateways need to operate in the field for many years. The longevity of the network requires that gateways be immune to a range of transient threats the equipment may encounter over its lifetime. As such, gateway data ports need to be safeguarded from overvoltage transient threats, including electrostatic discharge (ESD), electrical fast transients (EFT) and lightning surge.

Modern industrial networks rely on robust RS-485 communication links for long distance data transmission. These networks operate in harsh electromagnetic environments and must be capable of withstanding electrical overstress (EOS) events without damage. Semtech’s Protection Products Group application engineering team recently had the opportunity to work with Renesas Corporation engineers on a reference design for protecting Renesas’ fault-protected RS-485 transceivers, used in industrial applications.

I remember riding in the back of a taxi – I was half asleep and nearly half way around the world. I was just outside of Hangzhou, China, near the picturesque and iconic Xi Hu (Westlake) when a colleague nudged me and said, “Hey isn’t it crazy that you can travel the world selling a diode?” I thought, wow, that is crazy! It’s amazing actually.

In 1885, Karl Benz, a German engineer, invented the first functional automobile. Over the past 130 years, automobiles have evolved considerably. Semtech is proud to be a part of the automotive technology journey and is aiding this evolution by offering key technologies that contribute to the advancement of safety, reliability and performance of automobiles. In commemoration of the inventor’s birthday, November 25, we take a look at some key automotive applications for integrated circuits (IC), and highlight Semtech’s contribution (or participation) to their implementation.

Today’s consumers and enterprises demand the smartest, most-efficient, highest-performance electronics to enable efficiencies and strategic advantages within some of the fastest growing markets. Semtech’s wide range of innovative analog and mixed-signal semiconductors and advanced algorithms provide just that.