XMU 02¶

The XMU 02 seems to be some kind of CPRI front-haulmultiplexor. It appears to be used in situations where a (small number of) high-bitrate CPRI links from the DU is to be de-multiplexed to multiple more lower-bitrated CPRI links towards the RU.

It appears to be controlled via some RS485 based control channel. There are three MAX3485 transcevers for each of the three RJ45 connectors on the front (A1, A2, A3).

Internal structure¶

FPGA¶

Internally, it appears to be one large (44x44mm, >= 42x42 ball BGA) part, probably a FPGA, connected to the 14 SFP+ slots for CPRI.

Next to the FPGA are two SN74CB3T16211 24bit bus-switch/level-shifters.

SoC¶

There's a control SoC ("Ericsson ROP 101 1190/2") with FLASH + RAM

• Intel/Micron/Numonyx RC48F4400P0VB0E 512Mbit/64MByte NOR flash
• ISSI IS42S32800D-7TLI 256MBit/32MByte SDRAM

Clocking¶

There are three clock sections,

• Two seemingly identical sections comprised of
  • "ERC3105E 491.52" Part (491.52 MHz?)
  • EPCOS B5217 491.52 MHz VCXO cleanup filter
  • AD9510 Clock Distribution/PLL IC
  • MAX8869 LDO
• One section consisting of
  • VDSCLD 63.897 (63.897 MHz?)
  • AD9510 Clock Distribution/PLL IC
  • MAX8869 LDO