7.2.1 Design Requirements

For this design example, use the parameters shown in Table 7-1.

Table 7-1. Design Parameters

PARAMETER

VALUE

Pre-channel A to B PCB trace length(1) , LAB.

1 inches ≤ LAB ≤ 12 inches - LCD

Post-channel C to D PCB trace length(1) , LCD.

≤ 4 inches

Minimum distance of the AC capacitors from TUSB1002A, LAC-CAP

0.25 inches

Maximum distance of ESD component from the USB receptacle, LESD

0.6 inches

Maximum distance of series resistor (RESD) from ESD component, LR_ESD.

0.25 inches

CAC-USB1 AC-coupling capacitor (75nF to 265nF)

220nF

CAC-USB2 AC-coupling capacitor (297nF to 363nF)

Options:

•

RX1 and RX2 are DC-coupled to USB

receptacle

•

330nF AC-couple with RRX resistor

Optional RRX resistor (220kΩ ± 5%)

No used

Optional RESD (0Ω to 2.2Ω)

1Ω

VCC supply (3V to 3.6-V)

3.3V

Mode of Operation (Dual or Half Channel)

MODE = F (Floating) for USB3.2 Dual Channel

Linear Range (900mV, 1000mV, or 1200 mV)

1200mV (CFG[2:1] pins floating)

DC Gain (-2, -1, 0, +1, +2)

0dB (CFG[2:1] pins floating)

(1)

Maximum trace length assumes an insertion loss of 0.2dB/inch/GHz. If insertion loss is more than 0.2 dB/inch/GHz, then maximum

trace length must be reduced accordingly.

7.2.2 Detailed Design Procedure

The TUSB1002A differential receivers and transmitters have internal BIAS and termination. For this reason, the

TUSB1002A must be connected to the USB3.2 host and receptacle through external A/C coupling capacitors. In

this example 220nF capacitors are placed on TX2P and TX2N, RX1P and RX1N, and TX1P and TX1N. 330nF

A/C coupling capacitors along with 220kΩ resistors to ground are placed on the RX2P and RX2N. Inclusion

of the 330nF capacitors and 220k resistors is optional. The ordered list below details the three implementation

options for the RX2p/n path.

There are three implementation options for USB connector to the TUSB1002A RX pins:

1. DC couple the TUSB1002A RX pins to USB connector. No 330nF capacitors and no 220kΩ pulldown

resistors.

2. 330nF capacitors with 220kΩ resistors as shown in Figure 7-2. The purpose of 220kΩ resistors is to

discharge the capacitor within 250ms after a USB device is removed from the USB connector.

3. The stub from the 220kΩ resistor pad may create impedance discontinuities causing negative impact to

performance. Assuming leakage current from external components is enough to discharge capacitor, 330nF

capacitor without the 220kΩ resistor is a valid option.

TUSB1002A

SLLSF63C – MARCH 2018 – REVISED JULY 2024

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