Networking Clock Source

MDS 650-27 D

4

Revision 070505

Integrated Circuit Systems, Inc.

ICS650-27

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 50

Ω trace (a commonly

used trace impedance), place a 33

Ω resistor in series

with the clock line as close to the clock output pin as

possible. The nominal impedance of the clock output is

20

Ω.

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:

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.

Recommended Operation Conditions

Item

Rating

Supply Voltage, VDD

7 V

All Inputs and Outputs

-0.5 V to VDD+0.5 V

Ambient Operating Temperature

-40 to +85

°C

Storage Temperature

-65 to +150

°C

Junction Temperature

175

°C

Soldering Temperature

260

°C

Parameter

Min.

Typ.

Max.

Units

Ambient Operating Temperature

-40

+85

°C

Power Supply Voltage (measured in respect to GND)

+3.0

+3.3

+3.6

V