ICS477R-05ILF IDT, Integrated Device Technology Inc, ICS477R-05ILF Datasheet - Page 3

• Manufacturer Part Number: ICS477R-05ILF
• Description: IC QUAD PLL VCXO FOR HDTV 28QSOP
• Manufacturer: IDT, Integrated Device Technology Inc
• Type: Phase Lock Loop (PLL)r

Specifications of ICS477R-05ILF

• Pll: Yes with Bypass
• Input: Crystal
• Output: LVCMOS
• Number Of Circuits: 1
• Ratio - Input:output: 2:5
• Differential - Input:output: No/No
• Frequency - Max: 74.175MHz
• Divider/multiplier: No/No
• Voltage - Supply: 3.15 V ~ 3.45 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-QSOP
• Frequency-max: 74MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 477R-05ILF

IDT™ / ICS™ QUAD PLL WITH VCXO FOR HDTV
ICS477-05
QUAD PLL WITH VCXO FOR HDTV
External Components
The ICS477-05 requires a minimum number of external
components for proper operation.
Decoupling Capacitors
Decoupling capacitors of 0.01µF must be connected
between VDD and GND, as close to these pins 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 trace between the clock outputs and the
loads are over 1 inch, series termination should be
used. To series terminate a 50 trace (a commonly
used trace impedance) place a 33 resistor in series
with the clock line, as close to the clock output pin as
possible. The nominal impedance of the clock output is
20 .
Quartz Crystal
The ICS477-05 VCXO function consists of the external
crystal and the integrated VCXO oscillator circuit. To
assure the best system performance (frequency pull
range) and reliability, a crystal device with the
recommended parameters (shown below) must be
used, and the layout guidelines discussed in the
following section 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 ICS477-05 incorporates on-chip
variable load capacitors that “pull” (change) the
frequency of the crystal. The crystal specified for use
with the ICS477-05 is designed to have zero frequency
error when the total of on-chip + stray capacitance is 14
pF.
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 ICS477-05. 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.
See application note MAN05 for complete crystal
specifications.
3
Crystal Tuning Load Capacitors
The crystal traces should include pads for small fixed
capacitors, one between X1 and ground, and another
between X2 and ground. Stuffing of these capacitors on
the PCB is optional. The need for these capacitors is
determined at system prototype evaluation, and is
influenced by the particular crystal used (manufacture
and frequency) and by PCB layout. The typical required
capacitor value is 1 to 4 pF.
To determine the need for and value of the crystal
adjustment capacitors, you will need a PC board of your
final layout, a frequency counter capable of about 1 ppm
resolution and accuracy, two power supplies, and some
samples of the crystals which you plan to use in
production, along with measured initial accuracy for
each crystal at the specified crystal load capacitance,
CL.
To determine the value of the crystal capacitors:
1. Connect VDD of the ICS477-05 to 3.3 V. Connect pin
4 of the ICS477-05 to the second power supply. Adjust
the voltage on pin 3 to 0V. Measure and record the
frequency of the 27 MHz output.
2. Adjust the voltage on pin 4 to 3.3 V. Measure and
record the frequency of the same output.
To calculate the centering error:
Where:
f
error
being measured
If the centering error is less than ±25 ppm, no
adjustment is needed. If the centering error is more than
25 ppm negative, the PC board has excessive stray
capacitance and a new PCB layout should be
target
Error
xtal
= nominal crystal frequency
=actual initial accuracy (in ppm) of the crystal
=
10
6
x
------------------------------------------------------------------------------
f
3.0V
–
f
t
arg
et
f
t
arg
+
et
VCXO AND SYNTHESIZER
f
0V
ICS477-05
–
f
t
arg
et
–
error
REV H 062404
xtal