Advantech MMP3-21 Manual do Utilizador Página 81

  • Descarregar
  • Adicionar aos meus manuais
  • Imprimir
  • Página
    / 112
  • Índice
  • MARCADORES
  • Avaliado. / 5. Com base em avaliações de clientes
Vista de página 80
Advantech SOM-Express Design Guide
Chapter 5 Carrier Board Design Guidelines 81
5.10.3 Layout Guidelines
The following represents a summary of the layout and routing guideline.
5.10.3.1 Differential pairs
The PCI Express signals should be routed as differential pairs. The following is a
summary of general routing guidelines for the differential pair traces.
In SOM-Express platforms the PCI Express differential trace impendence
target is 100 # ± 20%.
It is important to equalize the total length of the traces in the pair throughout
the trace; each segment of trace length should be equal along the entire
length of the pair. Figure 5-47 shows an example. L
A
must equal to L
A
, L
B
must equal to L
B
…, and so on.
It is preferable to route TX and RX differential pairs alternately on the same
layer (TX pair next to RX pair rather than another TX pair).
Tight coupling within the differential pair and increased spacing to other
differential pairs helps to minimize EMI and crosstalk.
It is important to maintain routing symmetry between the two signals of a
differential pair.
LA
TX
RX
LA
Lz
Lz
LB
LB
Ly
Ly
LC
LC
Lx
Lx
RX
TX
Cao
Figure 5-47 Line equalization
Vista de página 80
1 2 ... 76 77 78 79 80 81 82 83 84 85 86 ... 111 112

Comentários a estes Manuais

Sem comentários