ICS849S625I Datasheet, PDF (12/24 Pages) Integrated Device Technology – Ten selectable differential LVPECL or LVDS outputs

ICS849S625I Data Sheet
CRYSTAL-TO-LVPECL/LVDS CLOCK SYNTHESIZER
Applications Information
Recommendations for Unused Input and Output Pins
Inputs:
REF_CLK Input
For applications not requiring the use of the reference clock, it can be
left floating. Though not required, but for additional protection, a 1k
resistor can be tied from the REF_CLK to ground.
Crystal Inputs
For applications not requiring the use of the crystal oscillator input,
both XTAL_IN and XTAL_OUT can be left floating. Though not
required, but for additional protection, a 1k resistor can be tied from
XTAL_IN to ground.
LVCMOS Control Pins
All control pins have internal pullups or pulldowns; additional
resistance is not required but can be added for additional protection.
A 1k resistor can be used.
Outputs:
LVPECL Outputs
All unused LVPECL outputs can be left floating. We recommend that
there is no trace attached. Both sides of the differential output pair
should either be left floating or terminated.
LVDS Outputs
All unused LVDS output pairs can be either left floating or terminated
with 100 across. If they are left floating, there should be no trace
attached.
Table 6. Recommended Crystal Specifications
Symbol Parameter
Value
Crystal Cut
Fundamental at Cut
f_T
f_S
C_L
C_O
ESR
Resonance
Frequency Tolerance
Frequency Stability
Load Capacitance
Shunt Capacitance
Equivalent Series Resistance
Aging @ 25 ⁰C
Parallel Resonance
±25ppm at 25⁰C
±25ppm over -40⁰C to +85⁰C
18pF
5pF - 7pF
20 - 50
±15ppm/10 Years Maximum
NOTE: External tuning capacitors must be used for proper operation.
Power Supply Voltage Sequence Information
No power sequence restrictions apply if V_CC and V_CCA are supplied
by the same power plane and the recommended V_CCA filter is used (
see Figure 6). V_CCO may be applied at any time before or after V_CC
and V_CCA are applied. If V_CC and V_CCA are not supplied by the same
power plane, V_CCA must be powered on before or at the same time
V_CC is applied. The V_CCO supply voltage may be applied at any time.
ICS849S625BYI REVISION A OCTOBER 1, 2012
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©2012 Integrated Device Technology, Inc.