USB4 ESD devices balance of protection and performance

USB4 ESD devices balance of protection and performance

New Products |
By Nick Flaherty

Nexperia has launched two Electrostatic Discharge (ESD) protection devices optimized for use with USB4 retimers and redrivers on high-speed data lines. 

The PESD2V8Y1BSF is designed to protect USB4 (Thunderbolt) interfaces while PESD4V0Y1BCSF is intended for use with both USB4 as well as HDMI 2.1. These use Nexperia’s TrEOS technology, which combines low clamping with low capacitance and high robustness.

Retimers and redrivers are commonly used in the design of high-speed USB4 interfaces. However, these result in shorter board traces which have a lower parasitic inductance, an unintended consequence of which is a reduction in the overall system-level ESD robustness.

The PESD2V8Y1BSF and PESD4V0Y1BCSF provide very fast Transmission Line Pulse (vfTLP) peak clamping voltages, which are even lower than USB4 protection solutions without visible trigger voltage in the standard I(V) TLP curve. This helps to compensate for the reduced inductance between protection and retimer, increasing overall system-level ESD robustness.

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To comply with budget loss recommendations for ESD, these devices are designed to have a low insertion loss of -0.29 dB @ 10 GHz and a return loss of -20.6 dB @ 10 GHz. The capacitance does not increase with operating voltage, offering the full RF performance up to the reverse standoff voltage.

The PESD2V8Y1BSF and PESD4V0Y1BCSF offer greater design flexibility as they can be placed immediately next to the connector of the device which they are protecting. This means that the AC coupling capacitance is protected as well. This places most of the line inductance between ESD protection and protected device to optimize system ESD performance.

“Nexperia enables design engineers to meet tight budgets on both insertion and return loss for high speed USB4 data lines by providing devices that minimize the impact of ESD protection on overall system budget,” said Stefan Seider, senior product manager at Nexperia. “These devices offer the optimum balance between optimizing system-level ESD robustness and RF performance.”

To maintain backward compatibility with older interface standards such as USB3.2, which can be connected over USB Type-C, the PESD2V8Y1BSF has a reverse standoff voltage (VRWM) of 2.8 V, while the PESD4V0Y1BCSF has a VRWM of 4 V for HDMI 2.1 as well.

The RF performance of the TrEOS technology used for both devices does not degrade over the operation voltage range. Apart from USB4 and HDMI 2.1, both parts can also be used to protect PCIe or DisplayPort interfaces. 

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