Kontron COMe Starterkit Eval T2 - Manual (Page 90)

COM Express Interfaces
2.10.3. Routing Considerations
Route SATA signals as differential pairs, with a 85 Ω differential impedance and a 50 Ω, single-
ended impedance. Ideally, a SATA pair is routed on a single layer adjacent to a ground plane.
SATA pairs should not cross plane splits. Keep layer transitions to a minimum. SATA routing
rules are also summarized in Section 6.5.8. 'Serial ATA Trace Routing Guidelines' on page 188.
As of the writing of this document, experience with SATA Gen3 implementations has shown that
Carrier Board redrivers on the TX/RX pairs may be necessary. Check with your Module provider
for further recommendations. Redrivers are available from vendors such as Texas Instruments,
Pericom and others. The TI SN75LVCP600S is a redriver part in use by some Module vendors.
PICMG ® COM Express ® Carrier Board Design Guide Rev. 2.0 / December 6, 2013
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