Super Speed Interface

Super speed transmission interfaces have specific requirements regarding signal loss and spatial constraints, necessitating components with low capacitance and compact size.

Information

ESD protection for transmission interfaces

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Rising demand for high-density streaming is driving faster data transmission in data centers and devices. USB now supports up to 40 Gbps and USB PD enables faster charging. Surge protection during plug-in or voltage fluctuation remains a key challenge.

Key factors for selecting ESD/EOS protection in super-speed interfaces:

1.Use low-capacitance components to maintain signal integrity.


2.Ensure IEC 61000-4-2 compliance (≥8 kV contact discharge).


3.Lower clamping voltage offers better protection.


4.Meet signal quality requirements in insertion loss and eye diagram tests.




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Frequency and capacitance estimation formula:

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Frequency vs Capacitance

1.Higher signal frequency requires lower capacitance.


2.To maintain signal integrity at high frequencies, ESD protection components must have ultra-low capacitance.


3.As frequency increases, the acceptable capacitance decreases to avoid signal distortion, insertion loss, and eye diagram degradation.


4.Typical design rule: the cutoff frequency of the RC filter formed by the ESD component should exceed the signal frequency by at least 2–3×.

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Comchip offers the CPDWZ5V0SBP-HF series with lower clamping voltage and reduced capacitance, optimized for various transmission interfaces. These components demonstrate excellent performance in both eye diagram analysis and S21 insertion loss testing. The ultra-low capacitance model, CPDWZ5V0P-HF, features a capacitance as low as 0.08 pF.