Embedded Solutions
Page 6
Headers and TestPoints
J6
and
J11
are used to select the VPWR source for position 0 and 1 respectively.
When the Shunt closes 1-2 – 12V is selected. With 2-3 closed 5V is selected. FET’s
are used to provide a low impedance path from the power supplies to VPWR for each
position. Options are in place on the PCB to allow hardwired selections for clients who
prefer a fixed voltage. The headers are not installed when the fixed voltage option is in
place. With pin 2 open VPWR will be open.
J12
,
13
, and
23
are used to select the bezel grounding option. 1-2 selects AC coupled,
2-3 selects DC coupled and open is open. J12 = PCIe Bezel. J13 = Slot 0. J23 = Slot
1.
J1
is an optional header for SMB connection. Pin 1 is data and pin 2 is clock. Both are
pulled up. 3
rd
party tools can be used to see the “innards” of the switch. Usually not
needed but handy if you are doing development or want to talk through the switch to the
XMC positions.
TP1
is an optional JTAG header used to connect to XMC 0. The pin definitions are in
the silk. 1: 3.3V, 2: GND, 3: TMS, 4: TDO, 5: TDI, 6: TCK, 7: TRST
J2
&
J19
control the voltage on 33,67 of P2 and P7 respectively when the SCSI
connector options are selected. 1-2 selects 3.3V and 2-3 selects ground on those pins.
The shunt and traces are rated for 1A. Not fuse protected.
J3
&
J20
control the voltage on 34,68 of P2 and P7 respectively when the SCSI
connector options are selected. 1-2 selects 3.3V and 2-3 selects ground on those pins.
The shunt and traces are rated for 1A. Not fuse protected.
P3, 4, 6
are optional power connectors to allow for added 12V power to be used by the
PCIe8LXMCX2. The PCIe gold fingers allow for about 60W of power to be consumed
by the board across all XMC voltages including power supply losses. In many cases
the power budget is more than sufficient. If your XMC’s require more power please
request one of the optional power connectors [discrete wire, 4 wire standard PC vert or
horizontal] to increase the 12V available. Both 12V entry points are diode coupled to
prevent the current back-feeding when an external or other supply is added.
P3: 1-2 = gnd, 3-4 = 12V. P4,6: 1= 12V, 2-3 = gnd.
