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Advantech SOM-Express Design Guide
84
Chapter 5 Carrier Board Design Guidelines
5.11 Serial ATA
SOM-Express provides up to four Serial ATA (SATA) interface.
5.11.1 Signal
Description
Table 5-30 shows SOM-Express Serial ATA signals for general purpose, including pin
number, signals, I/0, and descriptions.
Table 5-30 Serial ATA Signal Description
Pin Signal
I/O
Description
A16
A17
S
SATA0_TX-
O
Serial ATA or SAS Channel 0 transmit differential pair
A19
A20
S
SATA0_RX-
I
Serial ATA or SAS Channel 0 receive differential pair
B16
B17
S
SATA1_TX-
O
Serial ATA or SAS Channel 1 transmit differential pair
B19
B20
S
SATA1_RX-
I
Serial ATA or SAS Channel 1 receive differential pair
A22
A23
S
SATA2_TX-
O
Serial ATA or SAS Channel 2 transmit differential pair
A25
A26
S
SATA2_RX-
I
Serial ATA or SAS Channel 2 receive differential pair
B22
B23
S
SATA3_TX-
O
Serial ATA or SAS Channel 3 transmit differential pair
B25
B26
S
SATA3_RX-
I
Serial ATA or SAS Channel 3 receive differential pair
A28
ATA_ACT#
O
ATA (parallel and serial) or SAS activity indicator, active low
5.11.2 Design
Guidelines
5.11.2.1
Serial ATA AC Coupling Requirements
Both the TX and RX SATA differential pairs require AC coupling capacitors. Figure 5-
51 shows the connection for SOM-Express SATA signals. All AC coupling capacitors
close to the transmitter (TX) and receiver (RX) are placed on the SOM-Express
board. Please do not the place AC coupling capacitors on your carrier board.
Figure 5-51 SATA interconnect example