Embedded Solutions
Page 6
Headers and TestPoints
J6
is 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
, are used to select the bezel grounding option. 1-2 selects AC coupled, 2-3
selects DC coupled and open is open. J13 = PCIe Bezel. J12 = XMC bezel.
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 XMC if the bus is in
use. Usually not needed but handy if you are doing development.
TP1, TP2 are
optional JTAG header/pwr used to connect to the XMC. .025” sq post
header. The pin definitions are in the silk. 1: 3.3V, 2: GND, 1: TMS, 2: TDO, 3: TDI, 4:
TCK, 5: TRST
J2
controls the voltage on 33,67 of P2 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
controls the voltage on 34,68 of P2 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
is an optional power connector to allow for added 12V power to be used by the
PCIe8LXMCX1. 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 requires more power please
request the optional power connectors [2x3 PC power cable common with current PC
Power supplies] 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: 1-3 = +12, 4-6 = GND.
