ds21ft40 Maxim Integrated Products, Inc., ds21ft40 Datasheet - Page 87

• Manufacturer Part Number: ds21ft40
• Description: Ds21ft40 Four X Three 12 Channel E1 Framer
• Manufacturer: Maxim Integrated Products, Inc.

DS21FT40
POWER SUPPLY DE-COUPLING
In a typical PCB layout for the MCM, all of the VDD pins will connect to a common power plane and all
the VSS lines will connect to a common ground plane. The recommended method for de-coupling is
shown below in both schematic and pictorial form. As shown in the pictorial, the capacitors should be
symmetrically located about the device. Figure 18-1 uses standard capacitors, two .47 uf ceramics and
two .01uf ceramics. Since VDD and VSS signals will typically pass vertically to the power and ground
planes of a PCB, the de-coupling caps must be placed as close to the DS21FT40 as possible and routed
vertically to power and ground planes.
De-coupling scheme using standard tantalum caps. Figure 18-1
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