The channel C-D has a trace length of 2 inches with a 4mil trace width. Assuming 0.83dB per inch of insertion

loss, the 2 inch trace equates to about 1.66dB of loss at 5GHz. An additional 2dB of loss needs to be added

due to package, A/C coupling capacitor, and the USB 3.1 receptacle. The total loss is around 3.66dB. Because

channel C-D includes a USB 3.1 receptacle, the actual total loss can be much greater than 3.66dB due to the

fact that devices plugged into the receptacle will also have loss. The device plugged into receptacle will have

either a short or long channel. USB3.2 standard defines total loss limit of 23dB that is distributed as 8.5dB

for Host, 8.5dB for device, and 6.0dB for cable. With variable channel of devices plugged into the USB3.2

receptacle, the configurable TUSB1002A RX2P/N equalization settings is not as straight forward as Channel

A-B.

Engineer can not set TUSB1002A CH2_EQ[2:1] pins to the largest equalization setting to accommodate the

largest allowed USB3.2 device/cable loss of 14.5dB, because doing so will cause the TUSB1002A to operate

outside its linear range when a device with short channel is plugged into the receptacle. For this reason, TI

recommends configure the TUSB1002A CH2_EQ[2:1] pins to equalize a shorter device channel, which will

require the USB3.2 host to compensate for remaining channel loss for the worse case USB3.2 channel of

14.5dB. The definition of a short device channel is not specified in USB 3.2 specification. Therefore, an engineer

must make their own loss estimate of what constitutes a short device channel. For particular example, assume

the short channel is around 2 to 3dB. The channel loss of the device must be added to the estimated Channel

C-D loss minus the typical 3dB of de-emphasis. This means CH2_EQ[2:1] pins can be configured to handle a

loss of 3dB to 5dB.

7.2.3 ESD Protection

It may be necessary to incorporate an ESD component to protect the TUSB1002A from electrostatic discharge

(ESD). TI recommends following the ESD protection recommendations listed in Table 7-2. A clamp voltage

greater than value specified in Table 7-2 may require a RESD on each differential pin. Place the ESD component

near the USB connector.

Table 7-2. ESD Diodes Recommended Characteristics

Parameter

Recommendation

Breakdown voltage

≥ 3.5V

I/O line capacitance

Data rates ≤ 5Gbps: ≤ 0.50pF

Data rates > 5Gbps: ≤ 0.35pF

Delta capacitance between any P and N I/O pins

≤ 0.07pF

Clamping voltage at 8A IPP IO to GND (1)

≤ 4.5V

Typical dynamic resistance

≤ 30mΩ

(1)

According to IEC 61000-4-5 (8/20μs current waveform)

Table 7-3. Recommended ESD Protection Component

Manufacturer

Part Number

RESD to pass IEC 61000-4-2 Contact ±8kV

Nexperia

PUSB3FR4

2Ω

Nexperia

PESD2V8Y1BSF

2Ω

Texas Instruments

TPD1E04U04DPLR

2Ω

Texas Instruments

TPD4E02B04DQAR

2Ω

TUSB1002A

SLLSF63C – MARCH 2018 – REVISED JULY 2024

www.ti.com

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