ICS844S0258-07 Datasheet, PDF (9/21 Pages) Integrated Device Technology – Output enable signal for three LVDS outputs

ICS844S0258-07 Data Sheet
Applications Information
FEMTOCLOCK^® CRYSTAL/LVCMOS-TO-LVDS/LVCMOS FREQUENCY SYNTHESIZER
Power Supply Filtering Technique
As in any high speed analog circuitry, the power supply pins are
vulnerable to random noise. To achieve optimum jitter performance,
power supply isolation is required. The ICS844S0258-07 provides
separate power supplies to isolate any high switching noise from the
outputs to the internal PLL. V_DD, V_DDA, V_{DDO_LVDS} and V_{DDO_LVCMOS}
should be individually connected to the power supply plane through
vias, and 0.01µF bypass capacitors should be used for each pin.
Figure 1 illustrates this for a generic V_DD pin and also shows that
V_DDA requires that an additional 10 resistor along with a 10F
bypass capacitor be connected to the V_DDA pin.
3.3V
V_DD
.01µF _10Ω
V_DDA
.01µF
10µF
Figure 1. Power Supply Filtering
Power Supply Sequence Requirement
The ICS844S0258-07 has a power supply sequence requirement.
This device requires that V_DD and V_DDA are powered simultaneously.
This device has been characterized using the recommended power
supply filtering techniques in Figure 1.
Power Sequence:
1. V_DD and V_DDA
2. V_{DDO_LVCMOS} and V_{DDO_LVDS}
Recommendations for Unused Input and Output Pins
Inputs:
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.
REF_CLK Input
For applications not requiring the use of a reference clock input, it can
be left floating. Though not required, but for additional protection, a
1k resistor can be tied from the REF_CLK input 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:
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.
LVCMOS Output
All unused LVCMOS output can be left floating. There should be no
trace attached.
ICS844S0258CK-07 REVISION A DECEMBER 2, 2013
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©2013 Integrated Device Technology, Inc.