TMS320C6748_16 Datasheet, PDF (141/273 Pages) Texas Instruments – Fixed- and Floating-Point DSP

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TMS320C6748
SPRS590F – JUNE 2009 – REVISED MARCH 2014
6.14.2.3 PCB Stackup Specifications
Table 6-44 shows the stackup and feature sizes required for SATA.
Table 6-44. SATA PCB Stackup Specifications
PARAMETER
MIN
TYP
MAX
PCB Routing/Plane Layers
4
6
Signal Routing Layers
2
3
Number of ground plane cuts allowed within SATA routing region
0
Number of layers between SATA routing region and reference ground plane
0
PCB Routing Feature Size
4
PCB Trace Width w
4
PCB BGA escape via pad size
18
PCB BGA escape via hole size
8
Device BGA pad size ⁽¹⁾
(1) Please refer to the Flip Chip Ball Grid Array Package Reference Guide (SPRU811) for device BGA pad size.
UNIT
Layers
Layers
Layers
Mils
Mils
Mils
Mils
6.14.2.4 Routing Specifications
The SATA data signal traces are edge-coupled and must be routed to achieve exactly 100 Ohms
differential impedance. This is impacted by trace width, trace spacing, distance between planes, and
dielectric material. Verify with a proper PCB manufacturing tool that the trace geometry for both data
signal pairs results in exactly 100 ohms differential impedance traces. Table 6-45 shows the routing
specifications for the data and REFCLK signals.
Table 6-45. SATA Routing Specifications
PARAMETER
MIN
TYP
Device to SATA header trace length
REFCLK trace length from oscillator to Device⁽¹⁾
Number of stubs allowed on SATA traces
TX/RX pair differential impedance
100
Number of vias on each SATA trace
SATA differential pair to any other trace spacing
2*DS ⁽³⁾
(1) The SATA_REFCLK(P/N) pins include an internal 100 Ohms differential termination
(2) Vias must be used in pairs with their distance minimized.
(3) DS is the differential spacing of the SATA traces.
MAX
7000
2000
0
3
UNIT
Mils
Mils
Stubs
Ohms
Vias ⁽²⁾
6.14.2.5 Coupling Capacitors
AC coupling capacitors are required on the receive data pair as well as the REFCLK pair. Table 6-46
shows the requirements for these capacitors.
Table 6-46. SATA Bypass and Coupling Capacitors Requirements
PARAMETER
SATA AC coupling capacitor value
SATA AC coupling capacitor package size
MIN
TYP
MAX
0.3
10
12
0603
(1) LxW, 10 mil units, i.e., a 0402 is a 40x20 mil surface mount capacitor.
(2) The physical size of the capacitor should be as small as possible.
UNIT
nF
10 Mils ⁽¹⁾⁽²⁾
6.14.2.6 SATA Interface Clock Source requirements
A high-quality, low-jitter differential clock source is required for the SATA PHY. The SATA interface
requires a LVDS differential clock source to be provided at signals SATA_REFCLKP and
SATA_REFCLKN. The clock source should be placed physically as close to the processor as possible.
Copyright © 2009–2014, Texas Instruments Incorporated
Peripheral Information and Electrical Specifications 141
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