MDS 556-01 B

3

Revision 020204

Broadcom 25 MHz LVDS Clock

ICS556-01

Quartz Crystal

The ICS556-01 25 MHz LVDS Clock utilizes an

external crystal to generate a low phase noise output.

To assure the best system performance and reliability,

a crystal device with the recommended parameters

(shown below) must be used, and the layout guidelines

discussed in the following section shown must be

followed.

The frequency of oscillation of a quartz crystal is

determined by its “cut” and by the load capacitors

connected to it. The crystal specified for use with the

ICS556-01 is designed to have zero frequency error

when the total of on-chip plus stray capacitance is 5 pF.

Recommended Crystal Parameters:

Temperature Stability

Load Capacitance5 pf

Shunt Capacitance, C02 pF Max

Equivalent Series Resistance80

Ω Max

The external crystal must be connected as close to the

chip as possible and should be on the same side of the

PCB as the ICS556-01. There should be no via’s

between the crystal pins and the X1 and X2 device

pins. There should be no signal traces underneath or

close to the crystal.

The value (in pF) of these crystal caps should equal

capacitance in pF. Example: or a crystal with a 16 pF

load capacitance, each crystal capacitor would be 8 pF

[(16-12) x 2] = 8.

Absolute Maximum Ratings

Stresses above the ratings listed below can cause permanent damage to the ICS556-01. 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

0 to +70

°C

Storage Temperature

-65 to +150

°C

Soldering Temperature

260

°C

Parameter

Min.

Typ.

Max.

Units

Ambient Operating Temperature

0

+70

°C

Power Supply Voltage (measured in respect to GND)

+2.375

+2.625

V

Reference crystal parameters

Refer to page 3