IDT8N4S270 Data Sheet
LVDS FREQUENCY-PROGRAMMABLE CRYSTAL OSCILLATOR
Schematic Layout
Figure 2 shows an example IDT8N4S270 application schematic. The
schematic example focuses on functional connections and is
intended as an example only and may not represent the exact user
configuration. Refer to the pin description and functional tables in the
datasheet to ensure the logic control inputs are properly set. For
example OE and FSEL can be configured from an FPGA instead of
set with pull up and pull down resistors as shown.
capacitor on the VDD pin must be placed on the device side with
direct return to the ground plane though vias. The remaining filter
components can be on the opposite side of the PCB.
Power supply filter component 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 10kHz. If a specific frequency noise component is
known, such as switching power supplies 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.
As with any high speed analog circuitry, the power supply pins are
vulnerable to random noise, so to achieve optimum jitter performance
isolation of the VDD pin from power supply is required. 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 0.1µF
Logic Control Input Examples
Set Logic
Input to '1'
Set Logic
Input to '0'
VDD
VDD
RU1
1K
RU2
Not Install
To Logic
Input
pins
To Logic
Input
pins
RD1
Not Install
RD2
1K
3.3V
FB1
2
1
VD D
C4
10uF
BLM18BB221SN1
C5
0.1uF
Place 0.1uF bypass cap
directly adjacent to
the VDD pin.
U1
1
2
3
6
4
5
OE
C3
0.1uF
OE
VDD
DNU
GND
Q
Zo = 50 Ohm
Zo = 50 Ohm
nQ
+
-
R1
100
LVDS Receiver
Figure 2. IDT8N4S270 Schematic Example
IDT8N4S270CCD REVISION A AUGUST 31, 2012
12
©2012 Integrated Device Technology, Inc.