Toshiba ESD Protection Diodes
Toshiba's next-generation ESD diodes are used for high-speed interfaces and portable devices. High-speed interfaces, like USB 3, HDMI and gigabit ethernet, are everywhere now and their receivers have to be very sensitive in order to operate at high speeds and low voltages. This tends to make them more susceptible to damage from ESD events. And our devices are more portable than ever. We handle them frequently or even wear them throughout the day, so they are frequently exposed to potential damage from ESD. This makes it very challenging to effectively protect against ESD events while simultaneously supporting high-speed signals.
In order for a protection diode to be effective, it needs to have a minimal effect on the signal, a very low clamping voltage, and a fast response time to minimize voltage buildup. Typical process technologies force designers to select a low capacitance or low dynamic resistance, but Toshiba’s fourth generation process provides both in the same part.
For protection diodes, minimizing signal distortion generally means minimizing capacitance. Protection diodes present a capacitive load to the signal, which will degrade its performance, limiting rise times and the ability to meet eye diagram requirements. Toshiba’s EAP-IV TVS diodes feature a typical capacitance as low as 0.2 pF, minimizing design time and complexity to add them to high-speed signals.
This low capacitance level is complemented by a low clamping voltage and low dynamic resistance. A low clamping voltage is necessary to ensure the diode activates before the protected IC is damaged, but if the dynamic resistance is too high, it’s still possible for voltage to build up across the diode and damage the device. When these diodes reach their clamping voltage and activate, the IV curve demonstrates a snapback characteristic. This behavior helps to quickly reduce the voltage across the diode. Coupling this with a dynamic resistance as low as 0.5 Ω allows the diode to effectively protect against discharges.
Toshiba’s EAP-IV diodes are rated for ±20 kV air and contact discharges, and they provide this high level of protection after repeated ESD events, exhibiting a very minimal change in performance.
Diodes are available in uni- or bi-directional versions, with up to 4 channels per package. Multichannel devices use a flow-through design to simplify layout, eliminating the stubs typically used to connect them to signal lines. Packaging is small to support the confined nature of the intended applications, with single channel devices available in the small SOD-962 package, measuring just 0.32 mm x 0.62 mm.
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