ADA4355ABCZ datasheet(36/45 Pages) AD

36 / 45 page

ADA4355

Data Sheet

Rev. A | Page 36 of 45

PCB DESIGN TIPS

Signal Integrity Recommendations

Place the photodiode signal source as close as possible to the

ADA4355 input to minimize trace length and associated

parasitic capacitance. Clear away all ground layers directly

underneath the input trace to reduce parasitics even further.

Additionally, match all LVDS line (DCON, DCOP, FCON,

FCOP, D0AN, D0AP, D1AN, and D1AP) lengths to eliminate

potential timing issues.

Thermal Design Recommendations

The ADA4355 uses multiple VCC and GND balls to facilitate

the internal power and grounding requirements. All of these

balls must be connected for proper electrical connectivity within

the module. Additionally, the PCB connection of the multiple

VCC and GND balls is an integral part of the thermal design.

All of the ADA4355 VCC and GND balls must be connected to

a PCB copper plane with the lowest thermal resistance possible.

To achieve the best thermal performance, these planes must

have as many thermal vias as practical to provide the lowest

possible thermally resistive path for heat dissipation to flow

through the bottom of the PCB. Solder fill or plug these vias.

Surface-Mount Design

Table 14 is provided as an aid to PCB design to accommodate

CSP_BGA style surface-mount packages. For industry-standard

design recommendations, refer to IPC-7351, Generic Requirements

for Surface Mount Design and Land Pattern Standard.

Table 14. CSP_BGA Data for Use with Surface-Mount Design

Package

Ball Attach Type

Solder Mask Opening

Ball Pad Size

84-Ball CSP_BGA (BC-84-4)

Solder mask defined

0.35 mm diameter

0.40 mm diameter

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