SLLSE32G November 2010 – November 2017 TUSB1310A
PRODUCTION DATA.
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.
Texas Instruments’ TUSB1310A device is a single port, 5.0-Gbps USB 3.0 physical layer transceiver that is available in a lead-free, 175-ball, 12-mm × 12-mm NFBGA package (ZAY). The link controller interfaces to the TUSB1310A device are through a PIPE (16-bit wide operating at 250 MHz) and a ULPI (8-bit wide operating at 60 MHz) interface. The USB connector interfaces to the TUSB1310A device through a USB 3.0 SuperSpeed USB differential pair (TX and RX) and USB 2.0 differential pair (DP/DM).
Figure 6-1 represents a typical implementation of the TUSB1310A USB 3.0 physical layer transceiver that operates off of a single crystal or an external reference clock. The reference frequencies are selectable from 20, 25, 30, and 40 MHz. The TUSB1310A device provides a clock to the USB link layer controllers. The single reference clock allows the TUSB1310A device to provide a cost effective USB 3.0 solution with few external components and a minimum implementation cost.
Reference clock jitter is an important parameter. Jitter on the reference clock degrades both the transmit eye and receiver jitter tolerance, no matter how clean the rest of the PLL is, thereby impairing system performance. Additionally, a particularly jittery reference clock may interfere with PLL lock detection mechanism, forcing the lock detector to issue an unlock signal. A good quality, low jitter reference clock is required to achieve compliance with supported USB 3.0 standards. For example, USB 3.0 specification requires the random jitter (RJ) component of either RX or TX to be 2.42 ps (random phase jitter calculated after applying jitter transfer function [JTF]). As the PLL typically has a number of additional jitter components, the reference clock jitter must be considerably below the overall jitter budget.
If an external clock source is used, XI must be tied to the clock source and XO must be left floating.
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Frequency tolerance | Operational temperature | ±50 | ppm | ||
Frequency stability | 1 year aging | ±50 | ppm | ||
Rise and Fall time | 20% to 80% | 6 | nsec | ||
Reference clock RJ with JTF (1 sigma)(1)(2) | 0.8 | psec | |||
Reference clock TJ with JTF (total p-p)(2)(3) | 25 | psec | |||
Reference clock jitter (absolute p-p)(4) | 50 | psec |
Either a 20-MHz, 25-MHz, 30-MHz, or 40-MHz crystal can be selected. A parallel, 20-pF load crystal must be used if a crystal source is used.
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT |
---|---|---|---|---|---|
Frequency tolerance | Operational temperature | ±50 | ppm | ||
Frequency stability | 1 year aging | ±50 | ppm | ||
Load capacitance | 12 | 20 | 24 | pF |
Components must be placed close to the TUSB1310A device to reduce the trace length of the interface between the components and the TUSB1310A. If external capacitors cannot accommodate a close placement, shielding to ground is recommended.
The following rules apply for differential pair signals (DP/DM, SSTXP/SSTXN, and SSRXP/SSRXN):
Figure 6-3 and Figure 6-4 are for visual reference only.
The TUSB1310A device supports an external oscillator source or a crystal unit. If a clock is provided to XI instead of a crystal, XO is left open. Otherwise, if a crystal is used, the connection must adhere to the following guidelines.
Because XI and XO are coupled to other leads and supplies on the PCB, it is important to keep them as short as possible and away from any switching leads. It is also recommended to minimize the capacitance between XI and XO. This can be accomplished by connecting the VSSOSC lead to the two external capacitors CL1 and CL2 and shielding them with the clean ground lines. The VSSOSC must not be connected to PCB ground.
Load capacitance (CLOAD) of the crystal varying with the crystal vendors is the total capacitance value of the entire oscillation circuit system as seen from the crystal. It includes two external capacitors CL1 and CL2 in Figure 6-5. The trace length between the decoupling capacitors and the corresponding power pins on the TUSB1310A device must be minimized. It is also recommended that the trace length from the capacitor pad to the power or ground plane be minimized.
The TUSB1310A requires 1.1-V and 1.8-V digital power sources. Both VDD1P1 and VDD1P8 supplies must have 0.1-μF bypass capacitors to VSS (ground) in order for proper operation. The recommendation is one capacitor for each power terminal. Place the capacitor as close as possible to the terminal on the device and keep trace length to a minimum. Smaller value capacitors like 0.01-μF are also recommended on the digital supply terminals. When placing and connecting all bypass capacitors, high-speed board design rules must be followed.
Because circuit noise on the analog power terminals must be minimized, a Pi-type filter is recommended for each supply. Analog power terminals must have a 0.1-μF bypass capacitor connected to VSSA (ground) for proper operation. Place the capacitor as close as possible to the terminal on the device and keep trace length to a minimum. Smaller value capacitors (0.01-μF) are also recommended on the analog supply terminals.
When selecting bypass capacitors for the TUSB1310A device, X7R-type capacitors are recommended. The frequency versus impedance curves, quality, stability, and cost of these capacitors make them a logical choice for most computer systems.
The selection of bulk capacitors with low-ESR specifications is recommended to minimize low frequency power supply noise. Today, the best low-ESR bulk capacitors are radial leaded aluminum electrolytic capacitors. These capacitors typically have ESR specifications that are less than 0.01 Ω at 100 kHz. Also, several manufacturers sell D-size surface mount specialty polymer solid aluminum electrolytic capacitors with ESR specifications slightly higher than 0.01 Ω at 100 kHz. Both of these bulk capacitor options significantly reduce low frequency power supply noise and ripple.