78P2352-DB-CMI Maxim Integrated Products, 78P2352-DB-CMI Datasheet - Page 5

• Manufacturer Part Number: 78P2352-DB-CMI
• Description: MCU, MPU & DSP Development Tools 78P2352 Demo Board f Board for Coax Cble
• Manufacturer: Maxim Integrated Products

Specifications of 78P2352-DB-CMI

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

78P2352-DB Demo Board Manual
PCB DESIGN DESCRIPTION
The 78P2352-DB (D2352T8C) demo board is
constructed as a four-layer PC board. The top layer
has the major components and signal routes. The
bottom layer has bypass capacitors and mostly
miscellaneous discrete components, as well as
additional signal routes. The internal two layers have
ground and power supply planes only. The power
supply and ground pins of the 78P2352 LIU are
connected directly to these planes.
The ground layer is directly under the component
side of the board, followed by the power plane layer,
then the bottom layer.
GROUND
The ground layer uses a split plane to divide system
ground and frame (or chassis) ground. The frame
ground plane is on the line side (the primary side of
the transformer and the BNCs) and system digital
ground is the LIU side (the secondary side of the
transformer).
The chassis plane typically will be connected to the
equipment chassis, which connects to the facilities
Earth ground structure. The coax shield also
typically connects to the chassis at equipment or
patch panel bulkhead, providing a solid common
bonding tie-point to the facility’s grounding structure,
as specified in the ITU-T recommendation K.27.
VCC PLANE
As with the digital ground plane, the power plane
layer should only extends to the LIU side of the
transformer. The outer edge of the power plane is
kept 10 mils short of the ground plane’s outer edge
to avoid plane-to-plane current fringing at the plane
edges.
TX- COAX
GROUND
RX-COAX
FRAME
COPPER VOID
COMPONENT
GROUND
LIU
5
DECOUPLING
Two decades of caps are used on the D2352T8C
demo board, e.g. a mix of 0.1uF and 0.001uF.
Consult the application note for general guidelines.
ANALOG TRACES
All CMI transmitter and receiver differential pair
signal routes have a differential impedance of 75Ω to
the secondary side of the transformer.
The
transformer), as well as the line side receive pair, is
a 75Ω single-ended trace. The coax shield is
connected directly to the line-side chassis ground.
TR ANSFOR MER S
The 78P2352-DB (D2352T8C) uses 1:1CT wide
band transformers on transmit and receive.
following table lists the recommended transformers
from different vendors that can be fitted on the
78P2352-DB demo board:
Dual core transformers
Manufacturer
Halo
TAMURA
See application note for transformer specifications
and other recommended vendors and part numbers.
SAMPLE TEST RESULTS
Refer to Appendix A for sample test results.
SCHEMATICS
Refer to Appendix B for schematics and bill of
material.
TEST SETUP
Refer to Appendix C for recommended test setups.
line-side
transmit
pair
Part Number
TG04-TDK1N1
TTC-300
(primary
side
The
of