LMH1983SQ/NOPB National Semiconductor, LMH1983SQ/NOPB Datasheet - Page 35

• Manufacturer Part Number: LMH1983SQ/NOPB
• Description: IC VID CLK GEN MULTI RATE 40LLP
• Manufacturer: National Semiconductor
• Type: Clock Generatorr

Specifications of LMH1983SQ/NOPB

• Applications: Video Equipment
• Mounting Type: Surface Mount
• Package / Case: 40-LLP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

30085143
High-Precision, Stable A/V clock generation using a 27 MHz TCXO Reference
PCB Design Do's and Don'ts
DO whenever possible dedicate an entire layer to each power
supply. This will reduce the inductance in the supply plane.
DO use surface mount components whenever possible.
DO place bypass capacitors and filter components as close
as possible to each power pin.
DO place the loop filter components, including the buffer am-
plifier, and VCXO as close as possible to the LMH1983.
DON'T allow discontinuities in the ground planes – return cur-
rents follow the path of least resistance. For high frequency
signals this will be the path of least inductance.
DO make sure to match the trace lengths of all differential
traces.
DO remember that VIAs have significant inductance — when
using a VIA to connect to a power supply or ground layer, two
in parallel will reduce the inductance over a singe VIA.
DO connect the pad on the bottom of the package to a solid
ground connection. This contact is used as a major ground
connection as well as providing a thermal conduit which helps
to maintain a constant die temperature.
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