ICS728
L
OW
C
OST
27 MH
Z
3.3 V
OLT
VCXO
Description
The ICS728 combines the functions of a VCXO
(Voltage Controlled Crystal Oscillator) and PLL (Phase
Locked Loop) frequency doubler onto a single chip.
Used in conjunction with an external pullable quartz
crystal, this monolithic integrated circuit replaces more
costly hybrid (canned) VCXO devices. The ICS728 is
designed primarily for data and clock recovery
applications within end products such as set-top box
receivers.
The ICS728 exhibits a moderate VCXO gain of 110
ppm/V typical, when used with a high quality external
pullable quartz crystal.
The frequency of the on-chip VCXO is adjusted by an
external control voltage input into pin VIN. Because
VIN is a high impedance input, it can be driven directly
from an PWM RC integrator circuit. Frequency output
increases with VIN voltage input. The usable range of
VIN is 0 to 3.3 V.
Features
•
Ideal for set-top box applications using 13.5 MHz
external pullable crystal to generate lock 27 MHz
clock transport video clock
•
On-chip VCXO with guaranteed pull range of ±110
ppm minimum
•
VCXO input tuning voltage 0 to 3.3 V
•
Packaged in 8-pin SOIC (150 mil wide)
•
Available in Pb (lead) free package
Block Diagram
VIN
13.5 MHz
Pullable
Crystal
X1
X2
Voltage
Controlled
Crystal
Oscillator
PLL
Frequency
Doubler
27 MHz
(2x Crystal Frequency)
MDS 728 B
Integrated Circuit Systems
l
1
5 25 Race Street, San Jose, CA 9 512 6
l
Revision 012505
tel (40 8) 2 97-12 01
l
w w w. i c s t . c o m