ICS650-27 Datasheet, PDF (4/6 Pages) Integrated Circuit Systems – Networking Clock Source

ICS650-27
Networking Clock Source
External Components
The ICS650-27 requires a minimum number of external
components for proper operation.
Decoupling Capacitor
Decoupling capacitors of 0.01µF must be connected
between each VDD and GND (pins 4 and 6, pins 16
and 14), as close to the device as possible. For
optimum device performance, the decoupling capacitor
should be mounted on the component side of the PCB.
Avoid the use of vias in the decoupling circuit.
Series Termination Resistor
When the PCB trace between the clock outputs and the
loads are over 1 inch, series termination should be
used. To series terminate a 50Ω trace (a commonly
used trace impedance), place a 33Ω resistor in series
with the clock line as close to the clock output pin as
possible. The nominal impedance of the clock output is
20Ω.
Crystal Information
The crystal used should be a fundamental mode (do
not use third overtone), parallel resonant. Crystal
capacitors should be connected from pins X1 to ground
and X2 to ground to optimize the initial accuracy. The
value of these capacitors is given by the following
equation:
Crystal caps (pF) = (C_L - 6) x 2
In the equation, C_L is the crystal load capacitance. So,
for a crystal with a 16pF load capacitance, two 20 pF
[(16-6) x 2] capacitors should be used.
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS650-27. These ratings,
which are standard values for ICS commercially rated parts, are stress ratings only. Functional operation of
the device at these or any other conditions above those indicated in the operational sections of the
specifications is not implied. Exposure to absolute maximum rating conditions for extended periods can
affect product reliability. Electrical parameters are guaranteed only over the recommended operating
temperature range.
Item
Supply Voltage, VDD
All Inputs and Outputs
Ambient Operating Temperature
Storage Temperature
Junction Temperature
Soldering Temperature
Rating
7V
-0.5 V to VDD+0.5 V
-40 to +85°C
-65 to +150°C
175°C
260°C
Recommended Operation Conditions
Parameter
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Min.
-40
+3.0
Typ.
+3.3
Max.
+85
+3.6
Units
°C
V
MDS 650-27 D
4
Revision 070505
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