DRA722_17 Datasheet, PDF (370/408 Pages) Texas Instruments – Infotainment Applications Processor

DRA722, DRA724, DRA725, DRA726
SPRS956B – MARCH 2016 – REVISED JANUARY 2017
www.ti.com
Table 8-17. Compatible SATA Components and Modes (continued)
PARAMETER
Internal Cable
MIN
MAX
UNIT
-
-
-
SUPPORTED
YES
8.5.5.3 PCB Stackup Specifications
Table 8-18 shows the stackup and feature sizes required for these types of SATA connections.
Table 8-18. SATA PCB Stackup Specifications
PARAMETER
MIN
TYP
Number of ground plane cuts allowed within SATA routing
region
-
-
Number of layers between SATA routing area and
reference plane
-
-
PCB Routing clearance
4
PCB Trace width
4
MAX
0
0
UNIT
Cuts
Layers
Mils
Mils
8.5.5.4 Routing Specifications
The SATA data signal traces must be routed to achieve 100 Ohms (+/-10%) differential impedance and 60
ohms (+/-10%) single ended impedance. The signal ended impedance is required because differential
signals can’t be closely coupled on PCBs and therefore single ended impedance becomes important. 60
ohms is chosen for the single ended impedance to minimize problems caused by too low an impedance.
These impedances are impacted by trace width, trace spacing, distance to reference planes, and dielectric
material. Verify with a PCB design tool that the trace geometry for both data signal pairs results in as
close to 100 ohms differential and 60 ohms single ended impedance traces as possible. For best
accuracy, work with your PCB fabricator to ensure this impedance is met.
Table 8-19 shows the routing specifications for the SATA data signals.
Table 8-19. SATA Routing Specifications
PARAMETER
SATA signal trace length (device balls to SATA connector)
Differential pair trace skew matching
Number of stubs allowed on SATA traces⁽²⁾
TX/RX pair differential impedance
TX/RX single-ended impedance
Number of vias on each SATA trace
SATA differential pair to any other trace spacing
(1) Beyond this, signal integrity may suffer.
(2) Inline pads may be used for probing.
(3) DS = differential spacing of the SATA traces.
MIN
90
54
2×DS⁽³⁾
TYP
100
60
MAX
3050⁽¹⁾
5
0
110
66
0
UNIT
Mils
Mils
stubs
Ω
Ω
Vias
Item
ESD part number
Table 8-20. SATA Routing Recommendations
Description
None
Reason
ESD suppression generally not
used on SATA
370 Applications, Implementation, and Layout
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