TLF11955

September 1995

CGS700V

Commercial Low Skew PLL 1 to 9 CMOS Clock Driver

General Description

CGS700 is an off the shelf clock driver specifically designed

for today’s high speed processors It provides low skew out-

puts which are produced at different frequencies from three

fixed input references The XTALIN input pin is designed to

be driven from three distinct crystal oscillators running at

25 MHz 33 MHz or 40 MHz

The PLL using a charge pump and an internal loop filter

multiplies this input frequency to create a maximum output

frequency of four times the input

The device includes a TRI-STATE

control pin to disable

the outputs while the PLL is still in lock This function allows

for testing the board without having to wait to acquire the

lock once the testing is complete

(continued)

Features

Y

Guaranteed and tested

outputs

Y

Guaranteed

1Xoutputs

Y

Y

Output buffer of nine drivers for large fanout

Y

25 MHz – 160 MHz output frequency range

Y

Outputs operating at 4X 2X 1X of the reference

frequency for multi-frequency bus applications

Y

Selectable output frequency

Y

TRI-STATE output control with the PLL is in the lock

state

Y

Internal loop filter to reduce noise and jitter

Y

Y

Low frequency test mode by disabling the PLL

Y

Implemented on National’s Core CMOS process

Y

Symmetric output current drive

a

Y

28-pin PCC for optimum skew performance

Y

Guaranteed 2k ESD protection

Connection Diagram

Pin Assignment for PLCC

TLF11955 – 1

See NS Package Number V28A

TRI-STATE

is a registered trademark of National Semiconductor Corporation

Pin Description

PLCC Package

Pin

Name

Description

2

SKWSEL

Skew Test Selector Pin

3

CLK4

4X Clock Output

5

XTALIN

Crystal Oscillator Input

6

GND

Digital Ground

7

CLK1

0

1X Clock Output

9

CLK1

1

1X Clock Output

10

GND

Digital Ground

11

CLK1

2

1X Clock Output

12

TRI-STATE

Output TRI-STATE Control

13

SKWTST

Skew Testing Pin

14

CLK1

3

1X Clock Output

15

GND

Digital Ground

16

CLK1

4

1X Clock Output

17

18

EXTCLK

External Test Clock

19

GNDA

Analog Ground

20

21

EXTSEL

External Clock Mux Selector

22

GND

Digital Ground

23

CLK1

5

1X Clock Output

24

25

CLK1

6

1X Clock Output

26

CLK1SEL

CLK1 Multiplier Selector

27

GND

Digital Ground

28

CLK2

2X Clock Output

C1996 National Semiconductor Corporation

RRD-B30M66Printed in U S A