ICS728

MDS 728 B

1

Revision 012505

www.icst.com

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

external pullable crystal to generate lock 27 MHz

clock transport video clock

ppm minimum

Block Diagram

27 MHz

(2x Crystal Frequency)

X1

X2

Voltage

Controlled

Crystal

Oscillator

PLL

Frequency

Doubler

VIN

13.5 MHz

Pullable

Crystal