SLLSF36A August 2017 – September 2017 TUSB214-Q1
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.
The primary purpose of the TUSB214-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 TUSB214-Q1 can help to pass this eye mask.
A secondary purpose is to use the CD pin of the TUSB214-Q1 to control other blocks on the customer platform if so desired. Also, TUSB214-Q1 can be used as a CDP controller.
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].
For this design example, use parameters shown in the table below.
|VCC (3.0V to 3.6V)||3.3 V|
|I2C support required in system (Yes/No)||No|
|AC Boost||REQ||Level||AC Boost Level 2:
REQ = 3.83 K
|1.69 k ±1%||1|
|3.83 k ±1%||2|
|DC Boost||RDC1||RDC2||Level||Mid DC Level:
RDC1 = DNI
RDC2 = DNI
|22 kΩ - 47 kΩ||Do Not Install (DNI)||40 mV Low DC Boost|
|DNI||DNI||60 mV Mid DC Boost|
|DNI||22 kΩ - 47 kΩ||80 mV High DC Boost|
TUSB214-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 TUSB214-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.
|PLATFORM GOAL||SUGGESTED TUSB214-Q1 PLACEMENT|
|Pass USB Near End Mask||Close to measurement point|
|Pass USB Far End Eye Mask||Close to USB PHY|
|Cascade multiple TUSB214-Q1 to improve device enumeration||Midway between each USB interconnect|
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: