TMS320DM8148 Datasheet, PDF (318/343 Pages) Texas Instruments – TMS320DM814x DaVinci™ Digital Media Processors

TMS320DM8148, TMS320DM8147
SPRS647 – MARCH 2011
www.ti.com
8.18.2.2 Compatible SATA Components and Modes
Table 8-86 shows the compatible SATA components and supported modes. Note that the only supported
configuration is an internal cable from the processor host to the SATA device.
Transfer Rates
eSATA
xSATA
Backplane
Internal Cable (iSATA)
Table 8-86. SATA Supported Modes
PARAMETER
MIN
1.5
-
-
-
-
MAX
3.0
-
-
-
-
UNIT
Gbps
-
-
-
-
SUPPORTED
No
No
No
Yes
8.18.2.3 PCB Stackup Specifications
Table 8-87 shows the PCB stackup and feature sizes required for SATA.
Table 8-87. SATA PCB Stackup Specifications
PARAMETER
PCB routing/plane layers
Signal routing layers
Number of ground plane cuts allowed within SATA routing region
Number of layers between SATA routing region and reference ground plane
PCB trace width, w
PCB BGA escape via pad size
PCB BGA escape via hole size
Processor BGA pad size⁽¹⁾
(1) NSMD pad, per IPC-7351A BGA pad size guideline.
MIN
TYP
MAX UNIT
4
6
- Layers
2
3
- Layers
-
-
0 Cuts
-
-
0 Layers
-
4
- Mils
-
20
- Mils
-
10
Mils
0.4
mm
8.18.2.4 Routing Specifications
The SATA data signal traces must be routed to achieve 100 Ω (±20%) differential impedance and 60 Ω
(±15%) single-ended impedance. The single-ended impedance is required because differential signals are
extremely difficult to closely couple on PCBs and, therefore, single-ended impedance becomes important.
60 Ω 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 Ω differential impedance and 60 Ω single-ended impedance traces as possible. For best
accuracy, work with your PCB fabricator to ensure this impedance is met.
Table 8-88 shows the routing specifications for the SATA data signals.
Table 8-88. SATA Routing Specifications
PARAMETER
Processor-to-SATA header trace length
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) In-line pads may be used for probing.
(3) Vias must be used in pairs with their distance minimized.
(4) DS = differential spacing of the SATA traces.
MIN
80
51
2*DS ⁽⁴⁾
TYP
100
60
MAX
10 ⁽¹⁾
0
120
69
3
UNIT
Inches
Stubs
Ω
Ω
Vias ⁽³⁾
318 Peripheral Information and Timings
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