REVISION D 07/13/15 17 PROGRAMMABLE FANOUT BUFFER
5P1105 DATASHEET
5P1105 Application Schematic
The following figure shows an example of 5P1105 application schematic. Input and output terminations shown are intended as
examples only and may not represent the exact user configuration. In this example, the device is operated at V
DDD,
V
DDA
= 3.3V.
The decoupling capacitors should be located as close as possible to the power pin. A 12pF parallel resonant 8MHz to 40MHz
crystal is used in this example. Different crystal frequencies may be used. The C1 = C2 = 5pF are recommended for frequency
accuracy. If different crystal types are used, please consult IDT for recommendations. For different board layout, the C1 and C2
may be slightly adjusted for optimizing frequency accuracy.
As with any high speed analog circuitry, the power supply pins are vulnerable to random noise. To achieve optimum jitter
performance, power supply isolation is required. 5P1105 provides separate power supplies to isolate any high switching noise
from coupling into the part.
In order to achieve the best possible filtering, it is recommended that the placement of the filter components be on the device
side of the PCB as close to the power pins as possible. If space is limited, the 0.1uf capacitor in each power pin filter should be
placed on the device side. The other components can be on the opposite side of the PCB.
Power supply filter recommendations are a general guideline to be used for reducing external noise from coupling into the
devices. The filter performance is designed for a wide range of noise frequencies. This low-pass filter starts to attenuate noise
at approximately 10 kHz. If a specific frequency noise component is known, such as switching power supply frequencies, it is
recommended that component values be adjusted and if required, additional filtering be added. Additionally, good general design
practices for power plane voltage stability suggests adding bulk capacitance in the local area of all devices.
The schematic example focuses on functional connections and is not configuration specific. Refer to the pin description and
functional tables in the datasheet to ensure the logic control inputs are properly set.
