JAJSDO8 August 2017 TUSB212-Q1
PRODUCTION DATA.
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
8.1 Application Information
The primary purpose of the TUSB212-Q1 is to re-store the signal integrity of a USB High Speed channel up to the USB receptacle. The loss in signal quality stems from reduced channel bandwidth due to high loss PCB trace and other components that contribute a capacitive load. This can cause the channel to fail the USB near end eye mask. Proper use of the TUSB212-Q1 can help to pass this eye mask.
A secondary purpose is to use the CD pin of the TUSB212-Q1 to control other blocks on the customer platform if so desired.
8.2 Typical Application
A typical application is shown in Figure 6. In this setup, D2P and D2M face the USB connector while D1P and D1M face the USB host. If desired, the orientation may be reversed [that is, D2 faces transceiver and D1 faces connector].
Figure 6. Typical Application
8.2.1 Design Requirements
For this design example, use parameters shown in the table below.
Table 3. Design Parameters
| PARAMETER | VALUE | |||
|---|---|---|---|---|
| VCC (3.0V to 3.6V) | 3.3V | |||
| I2C support required in system (Yes/No) | No | |||
| AC Boost | REQ | Level | AC Boost Level 2: REQ = 3.83K |
|
| 0-ohms | 0 | |||
| 1.69k +/- 1% | 1 | |||
| 3.83k +/- 1% | 2 | |||
| DNI | 3 | |||
| DC Boost | RDC1 | RDC2 | Level | Mid DC Level: RDC1 = DNI RDC2 = DNI |
| 22k - 47k ohms | Do Not Install (DNI) | 40mV Low DC Boost | ||
| DNI | DNI | 60mV Mid DC Boost | ||
| DNI | 22k - 47k ohms | 80mV High DC Boost | ||
8.2.2 Detailed Design Procedure
TUSB212-Q1 requires a valid reset signal as described in the power supply recommendations section. The capacitor at RSTN pin is not required if a microcontroller drives the RSTN pin according to recommendations.
VREG pin is the internal LDO output that requires a 0.1-μF external capacitor to GND to stabilize the core.
The ideal AC/DC Boost setting is dependent upon the signal chain loss characteristics of the target platform. The general recommendation is to start with AC Boost level 0, and then increment to AC Boost level 1, etc. when needed. Same applies to the DC boost setting where it is recommended to plan for the required pad to change boost settings.
In order for the TUSB212-Q1 to recognize any change to the AC or DC boost settings, the RSTN pin must be toggled. This is because the EQ and DC_BOOST pins are latched on power up and the pins are ignored thereafter.
Further D1P has to be shorted to D2P and D1M shorted to D2M on the board for correct functionality of the device.
Placement of the device is also dependent on the application goal. Table 4 summarizes our recommendations.
Table 4. Platform Placement Guideline
| PLATFORM GOAL | SUGGESTED TUSB212-Q1 PLACEMENT |
|---|---|
| Pass USB Near End Mask | Close to measurement point |
| Pass USB Far End Eye Mask | Close to USB PHY |
| Cascade multiple TUSB212-Q1 to improve device enumeration | Midway between each USB interconnect |
8.2.2.1 Test Procedure to Construct USB High Speed Eye Diagram
NOTE
USB-IF certification tests for High Speed eye masks require the mandated use of the USB-IF developed test fixtures. These test fixtures do not require the use of oscilloscope probes. Instead they use SMA cables. More information can be found at the USB-IF Compliance Updates Page. It is located under the ‘Electricals’ section, ID 86 dated March 2013.
The following procedure must be followed before using any oscilloscope compliance software to construct a USB High Speed Eye Mask:
8.2.2.1.1 For a Host Side Application
- Configure the TUSB212-Q1 to the desired AC and DC boost settings.
- Power on (or toggle the RSTN pin if already powered on) the TUSB212-Q1
- Using SMA cables, connect the oscilloscope and the USB-IF host-side test fixture to the TUSB212-Q1
- Enable the host to transmit USB TEST_PACKET
- Execute the oscilloscope USB compliance software.
- Repeat the above steps in order to re-test TUSB212-Q1 with different AC and DC boost settings.
8.2.2.1.2 For a Device Side Application
- Configure the TUSB212-Q1 to the desired AC and DC boost settings.
- Power on (or toggle the RSTN pin if already powered on) the TUSB212-Q1
- Connect a USB host, the USB-IF device-side test fixture, and USB device to the TUSB212-Q1. Ensure that the USB-IF device test fixture is configured to the ‘INIT’ position
- Allow the host to enumerate the device
- Enable the device to transmit USB TEST_PACKET
- Using SMA cables, connect the oscilloscope to the USB-IF device-side test fixture and ensure that the device-side test fixture is configured to the ‘TEST’ position.
- Execute the oscilloscope USB compliance software.
- Repeat the above steps in order to re-test TUSB212-Q1 with different AC and DC boost settings.
8.2.3 Application Curves
Figure 8. Eye Diagram Bench Setup
Figure 9. No TUSB212-Q1
Figure 10. Low DC Boost, AC Boost Level 0
Figure 12. High DC Boost, AC Boost Level 0
Figure 14. Mid DC Boost, AC Boost Level 1
Figure 16. Low DC Boost, AC Boost Level 2
Figure 18. High DC Boost, AC Boost Level 2
Figure 20. Mid DC Boost, AC Boost Level 3
Figure 11. Mid DC Boost, AC Boost Level 0
Figure 13. Low DC Boost, AC Boost Level 1
Figure 15. High DC Boost, AC Boost Level 1
Figure 17. Mid DC Boost, AC Boost Level 2
Figure 19. Low DC Boost, AC Boost Level 3
Figure 21. High DC Boost, AC Boost Level 3