ESD SIM : “Mirror, Mirror on the Wall, Is This ESD Protector the Fairest of Them All?”

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Electronic devices must operate in increasingly harsher environments. As sensors multiply and components are embedded in everyday items, such as clothing, circuits must withstand greater shocks, or humidity. Therefore, designers have to find ways to better safeguard their systems. However, this can be extremely expensive and time-consuming, requiring multiple prototypes to find the right components. This is why ST has recently launched the new and free ESD SIM online software tool that greatly facilitates designing protection against electrostatic discharges (ESD). Created by Transim using Keysight EEsof EDA and ADS software, the tool will help engineers choose the right components and test their designs in fewer than 10 clicks.

The Necessity of ESD SIM

When talking about static electricity, most people think of walking on a carpet, and an engineer must anticipate these sorts of situations. However, a discharge is only felt by humans when it reaches 3,000 V or more. This means that ESDs caused by clothing, which usually range between 500 V and 2,500 V, can also have dramatic effects on circuits without anyone ever being aware that an ESD took place. Hence, the victim of a catastrophic failure caused by an ESD may not understand why a device has stopped functioning and will simply attribute it to a defect by the manufacturer. Furthermore, damage can be latent, meaning that the device may be working as usual until an event demands the use of a damaged circuit, resulting in failures long after the voltage spike occurred.

The problem is that protecting against ESDs is anything but straightforward these days. Most consumer devices use either a wireless module, such as Bluetooth, or a USB port. In these cases, ESD protectors featuring a large capacitance can cause serious signal distortion or attenuation during high-speed data transfers. Furthermore, big components can also be problematic when one tries to shrink a design. However, using an ESD protector with a small capacitance may not be good enough.

Damages of an ESD on Silicon

Damage from an ESD on Silicon

Setting up ESD SIM

The TVS Selector in ESD SIM

The TVS Selector in ESD SIM (click to enlarge)

 

This is where ESD SIM can make choosing the right protector a lot simpler. Before starting, it is advisable to register or log onto ST’s Website. Once on the ESD SIM’s homepage, one must choose between Basic Mode or Advanced Mode. In the first one, the simulator will use default values. In the latter, it is possible to use custom parameters to match a specific design. For the sake of this demonstration, we will use Basic Mode.

The next step is choosing a TVS (Transient Voltage Suppressor, an ESD protector) from a list of ST components. Let’s imagine that we are trying to determine the viability of a protector for a device using a USB Type-C port. Hence, we choose “ESD for Digital Signals” under Protection Type, and select “USB 3.1 Gen1 Type-C” as the Signal Standard. At that time, a list of components will appear. It is possible to filter them by contact discharge and packages.

For this demonstration, we will select the USBULC6–2M6. It is a component that belongs to the same family of ESD protector as the one used by the P-NUCLEO-USB001, a development board meant to help engineers integrate USB Type-C ports and USB Power Delivery 2.0 technologies. Once we click on the check box, a button entitled ”Simulate“ will appear. Not all TVSs are setup to work with the simulator yet, but those that are compatible have the mention ”ESD-SIM“ in the column ”Simulator”.

The Power of the Simulator

Results of the ESD SIM Simulation

Results of the ESD SIM Simulation (click to enlarge)

 

To ensure that the ESD Protector we’ve chosen is compatible with the design we are trying to create, we can simply push “Simulate.” The software powered by Keysight EEsof will input the default values and run a simulation that will quickly tell if the component meets all the necessary standards. In our simple example, we can see that the USBULC6–2M6 is perfect for the job.

It is important to note this example only scratches the surface of what the simulator can do. On top of being able to use custom parameters in Advanced Mode, the system will guide the user toward better-suited protectors when it detects that the selected TVS doesn’t satisfy the pre-defined objectives. ESD SIM finally offers a summary of the simulation, and the ability to download the results. Engineers using Keysight EEsof ADS can also download an ADS Model Library of ST’s products from the download area. It will allow them to include ST part models in their own designs.

To try ESD SIM for yourself, please visit ST’s website.