MK2746 View Datasheet(PDF) - Integrated Circuit Systems

Part Name

Description

Manufacturer

MK2746

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Integrated Circuit Systems 

MK2746

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External Component Selection

The MK2746 requires a minimum number of external

components for proper operation.

Decoupling Capacitors

Decoupling capacitors of 0.01µF should be connected

between VDD and GND as close to the MK2746 as

possible. For optimum device performance, the

decoupling capacitors 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 traces 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 Tuning Load Capacitors

For a crystal input, a parallel resonant fundamental

mode crystal should be used. Crystal capacitors must

be connected between each of the pins X1 and X2 to

ground. The value (in pF) of these crystal caps should

equal (CL-6)*2. In this equation CL is equal to the

crystal load capacitance in pF. As an example, for a

crystal with an 18 pF load capacitance, each crystal

capacitor would be 24 pF [(18-6)*2=24].

Absolute Maximum Ratings

PCB Layout Recommendations

For optimum device performance and lowest output

phase noise, the following guidelines should be

observed.

1) The 0.01µF decoupling capacitor should be mounted

on the component side of the board as close to the

VDD pin as possible. No vias should be used between

decoupling capacitor and VDD pin. The PCB trace to

VDD pin should be kept as short as possible, as should

the PCB trace to the ground via. Distance of the ferrite

bead and bulk decoupling from the device is less

critical.

2) The external crystal should be mounted just next to

the device with short traces. The X1 and X2 traces

should not be routed next to each other with minimum

spaces, instead they should be separated and away

from other traces.

3) To minimize EMI the 33Ω series termination resistor,

if needed, should be placed close to the clock output.

4) An optimum layout is one with all components on the

same side of the board, minimizing vias through other

signal layers (the ferrite bead and bulk decoupling

capacitor can be mounted on the back). Other signal

traces should be routed away from the MK2746. This

includes signal traces just underneath the device, or on

layers adjacent to the ground plane layer used by the

device.

Stresses above the ratings listed below can cause permanent damage to the MK2746. 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

Soldering Temperature

Rating

7V

-0.5 V to VDD+0.5 V

0 to +70°C

-65 to +150°C

260°C

MDS 2746 A

3

Revision 100802

Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com

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