SLVA793A june   2016  – august 2023 ESD122 , ESDS304 , TPD1E04U04 , TPD2E1B06 , TPD2EUSB30 , TPD4E004 , TPD4E02B04 , TPD4E05U06-Q1 , TPD6E004

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Why Impedance Mismatches Matter
  6. 3USB 3.0 Gen 1
  7. 4USB 3.1 Gen 2
  8. 5Summary
  9. 6References
  10. 7Revision History

4 USB 3.1 Gen 2

While USB 3.1 Gen 1 supports a data rate of 10 Gbps and requires the ESD protection diode capacitance to be <0.5pF, USB 3.1 Gen 2 supports a data rate of 20 Gbps and requires the ESD protection diode capacitance to be <0.3pF. Figure 4-1, Figure 4-2 and Figure 4-3 map out the data eye without an ESD protection diode, with the TPD4E02B04 protection diode, and with a 0.5-pF protection diode.

GUID-BBA7CDA6-14C4-4386-9EED-47BA92950B57-low.png Figure 4-1 USB 3.1 Gen 2 Eye Diagram without ESD Protection
GUID-0D312F2A-4233-4C9B-A6A0-48D84BAD0741-low.png Figure 4-2 USB 3.1 Gen 2 Eye Diagram with TPD4E02B04DQA ESD Protection
GUID-6DF396ED-C13D-485B-B3E4-CB070932465B-low.png Figure 4-3 USB 3.1 Gen 2 Eye Diagram with 0.5-pF ESD Protection

Table 4-1 lists the eye diagram measurements with and without ESD protection.

Table 4-1 Eye Diagram Measurements with and without ESD Protection
No ESD Protection TPD4E02B04 0.5-pF ESD Protection
Rise Time 63.55 ps 67.11 ps NA
Fall Time 63.77 ps 66.15 ps NA
Eye Height 132.3 mV 112 mV NA
Eye Width 84 ps 81.93 ps NA
Jitter(PP) 15.6 ps 18.07 ps NA
Jitter(RMS) 2.725 ps 3.167 ps NA

The 20-Gbps signal is still able to maintain signal integrity with the low capacitance of the TPD4E02B04 while providing ESD protection for the Gen 2 USB 3.1 transmitter. When using an ESD protection diode with a capacitance of 0.5 pF, the results show an eye diagram that does not have distinct data. This visualizes the effect of high capacitance on a high speed data signal.

Various PCB designs have many different specification needs. Listed below are some additional devices to TPD4E02B04 that meet the ultra-low capacitance needs of high-speed signals while utilizing less PCB space. Even more devices can be found online with the Product Selection Tool. These devices come with a variety of channel coverages, package sizes, Bi/uni directional capabilities, surge ratings, and clamping voltages.

Table 4-2 ESD Protection Device Quick Select
TPD4E02B04 TPD1E01B04 TPD1E05U06
Vrwm (V) 3.6 3.6 5.5
Package Type USON DPL, DPY SOT-5X3,DPL
Package Size (L x W) (mm) 2.5x 1 0.6x 0.3, 1.0 x 0.6 1.6x0.8, 1.0x0.6
Bi-/uni-directional Bi-directional Bi-directional Uni-directional
Number of Channels 4 1 1
Clamping Voltage 6.6 7.0 18
IO Capacitance (typ) (pF) 0.25 0.18 0.4
IEC61000-4-5 (A) 2.0 2.5 2.5
IEC61000-4-2 contact (±kV) 12 15 12