ICS840004AG-11LF IDT, Integrated Device Technology Inc, ICS840004AG-11LF Datasheet - Page 9

• Manufacturer Part Number: ICS840004AG-11LF
• Description: IC FREQ SYNTHESIZER 20-TSSOP
• Manufacturer: IDT, Integrated Device Technology Inc
• Series: HiPerClockS™, FemtoClock®r
• Type: Frequency Synthesizerr

Specifications of ICS840004AG-11LF

• Pll: Yes
• Input: Crystal
• Output: LVCMOS, LVTTL
• Number Of Circuits: 1
• Ratio - Input:output: 1:4
• Differential - Input:output: No/No
• Frequency - Max: 140MHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 3.135 V ~ 3.465 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Frequency-max: 175MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 840004AG-11LF

Crystal Input Interface
The ICS840004-11 has been characterized with 18pF parallel
resonant crystals. The capacitor values shown in Figure 2 below
were determined using a 25MHz, 18pF parallel resonant crystal and
were chosen to minimize the ppm error.
LVCMOS to XTAL Interface
The XTAL_IN input can accept a single-ended LVCMOS signal
through an AC coupling capacitor. A general interface diagram is
shown in Figure 3. The XTAL_OUT pin can be left floating. The input
edge rate can be as slow as 10ns. For LVCMOS inputs, it is
recommended that the amplitude be reduced from full swing to half
swing in order to prevent signal interference with the power rail and
to reduce noise. This configuration requires that the output
impedance of the driver (Ro) plus the series resistance (Rs) equals
Figure 3. General Diagram for LVCMOS Driver to XTAL Input Interface
ICS840004-11 Data Sheet
ICS840004AG-11 REVISION A SEPTEMBER 16, 2009
V
CC
Ro
Rs
Zo = Ro + Rs
50Ω
V
CC
R1
R2
0.1µf
XTAL_IN
XTAL_OUT
9
Figure 2. Crystal Input Interface
the transmission line impedance. In addition, matched termination at
the crystal input will attenuate the signal in half. This can be done in
one of two ways. First, R1 and R2 in parallel should equal the
transmission line impedance. For most 50Ω applications, R1 and R2
can be 100Ω. This can also be accomplished by removing R1 and
making R2 50Ω. By overdriving the crystal oscillator, the device will
be functional, but note, the device performance is guaranteed by
using a quartz crystal.
FEMTOCLOCK™ CRYSTAL-TO-LVCMOS/LVTTL FREQUENCY SYNTHESIZER
18pF Parallel Crystal
X1
©2009 Integrated Device Technology, Inc.
C1
22p
C2
22p
XTAL_IN
XTAL_OUT