AN11001
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Application note
Rev. 1 — 7 March 2011
11 of 17
NXP Semiconductors
AN11001
CBTL02042A switching application for mSATA, PCIe Mini-Card
5. Alternative
design
using CBTL02042A or CBTL04082A
In the design example above, only one interface is active at a time. For example, when a
Mini-Card is inserted into the Mini-Card/mSATA connector socket, the PCI Express
interface is selected, and the SATA interface is inactive. Instead of leaving SATA interface
inactive in this configuration, a motherboard design may reclaim the SATA interface for a
form-factor hard disk drive. A conceptual application diagram is shown in
below,
and it can be realized using either two CBTL02042As or one CBTL04082A/CBTL04083A.
The following paragraphs discuss the design implementation in detail. While using either
topology, a designer should pay special attention to the insertion loss caused by the
multiplexers, and adjust the trace length accordingly. The SATA interface signals to
Mini-Card/mSATA connector go through the multiplexer twice, thus insertion loss caused
by the multiplexers would need to be accounted for twice as well. From the trace length
calculation discussed in
Section 4.3 “Topology with CBTL02042A as a switch for
, a typical SATA trace length of 7 inches (17.78 cm) will need to deduct
5 inches (12.7 cm) to 6 inches (15.24 cm) to compensate the loss from the multiplexers.
This only leaves 1 inch (2.54 cm) to 2 inches (5.08 cm) of SATA signal traces to route
between the controller and the Mini-Card/mSATA connector. Depending on locations of
the controllers and connectors on motherboards, routing such short SATA signal traces
can be very difficult.
Fig 8.
Alternative PCIe/SATA interface use case block diagram
019aab325
PCIe
HOST CONTROLLER
SATA
HOST CONTROLLER
Mini-Card/mSA
T
A
CONNECT
OR
S
ATA
CONNECT
OR
select
1
SATA
↔
Mini-Card connector
PCIe
↔
Mini-Card connector
SATA
↔
SATA HDD connector
0
0
1
0