AM3359, AM3358, AM3357, AM3356, AM3354, AM3352
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SPRS717H –OCTOBER 2011–REVISED MAY 2015
Complete stackup specifications are provided in Table 7-46.
Table 7-46. PCB Stackup Specifications
(1)
NO. PARAMETER MIN TYP MAX UNIT
1 PCB routing and plane layers 4
2 Signal routing layers 2
3 Full ground layers under DDR2 routing region 1
4 Number of ground plane cuts allowed within DDR2 routing region 0
5 Full VDDS_DDR power reference layers under DDR2 routing region 1
6 Number of layers between DDR2 routing layer and reference ground plane 0
7 PCB routing feature size 4 mils
8 PCB trace width, w 4 mils
9 PCB BGA escape via pad size
(2)
18 20 mils
10 PCB BGA escape via hole size
(2)
10 mils
11 Single-ended impedance, Zo
(3)
50 75 Ω
12 Impedance control
(4)(5)
Zo-5 Zo Zo+5 Ω
(1) For the DDR2 device BGA pad size, see the DDR2 device manufacturer documentation.
(2) A 20-10 via may be used if enough power routing resources are available. An 18-10 via allows for more flexible power routing to the
AM335x device.
(3) Zo is the nominal singled-ended impedance selected for the PCB.
(4) This parameter specifies the AC characteristic impedance tolerance for each segment of a PCB signal trace relative to the chosen Zo
defined by the single-ended impedance parameter.
(5) Tighter impedance control is required to ensure flight time skew is minimal.
Copyright © 2011–2015, Texas Instruments Incorporated Peripheral Information and Timings 163
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