SYNCHRONOUS ETHERNET FREQUENCY TRANSLATOR

ICS840271I

1

ICS840271BGI REV. A APRIL 23, 2009

General Description

The ICS840271I is a PLL-based Frequency

Translator intended for use in telecommunication

applications such as Synchronous Ethernet. The

internal PLL translates Ethernet clock frequencies

such as 125MHz (1Gb Ethernet), 156.25MHz

(10GbE XAUI) and 161.1328MHz (10Gb Ethernet) to an output

frequency of 25MHz. The PLL does not any require external

components. The input frequency is selectable by a 2-pin

interface. The ICS840271I is optimized for low cycle-to-cycle jitter

on the 25MHz output signal. The input of the device accepts

differential (LVPECL, LVDS, LVHSTL, SSTL, HCSL) or

single-ended (LVCMOS) signals. The extended temperature range

supports telecommunication and networking equipment

requirements. The ICS840271I uses a small RoHS 6, 8-pin

TSSOP package and is an effective solution for space-constrained

applications.

Features

applications

16

Ω output impedance

LVHSTL, SSTL, HCSL input levels

161.1328MHz

input with external single-ended (LVCMOS/LVTTL) input levels

output

HiPerClockS™

ICS

ICS840271I

8 Lead TSSOP

4.40mm x 3.0mm x 0.925mm

package body

G Package

Top View

Pin Assignment

1

2

3

4

8

7

6

5

nCLK

CLK

SEL0

GND

Q

SEL1

25 MHz

Q

SEL(1:0)

Input Control Logic

CLK

nCLK

00 = PLL Bypass

01 = 161.1328125MHz

10 = 156.2500000MHz

11 = 125.0000000MHz

PLL

Pre-

divider

Output

divider

Feedback

divider

Block Diagram