Rainbow Electronics MAX9476 User Manual

General Description

The MAX9476 low-cost, high-performance clock syn­thesizer with an 8kHz input reference clock provides six
buffered LVTTL clock outputs at 35.328MHz. The clock
synthesizer can be used to generate the clocks for sys­tems using T1, E1, T3, E3, and xDSL.

The MAX9476 features a phase-lock loop (PLL) that uses
a voltage-controlled crystal oscillator (VCXO). The inter­nal PLL phase locks the external crystal (35.328MHz) to
the 8kHz input reference clock. In addition, this device
generates a jitter-suppressed output that provides a bet­ter source for the reference clock relay.

The MAX9476 is available in a 24-pin TSSOP package
and operates over the extended operating temperature
range of -40°C to +85°C and a single +3V to +3.6V
power-supply range. For using lower value external
crystals, refer to the MAX9486 data sheet.

Applications

Telecom Equipment Using T1, E1, T3, E3, and
ISDN Protocols

xDSL Equipment in CO with Interface to the
Telecom Protocols

Features

♦ 8kHz Input-Reference CLK

♦ 4ps

RMS

(typ) Output Jitter

♦ High-Jitter Rejection on the Reference CLK

♦ Synthesizer Locks to the 8kHz Reference with a

±100ppm Range

♦ Output Frequency: 35.328MHz

♦ Six Buffered LVTTL Low-Jitter Outputs

♦ One 8kHz Reference CLK Relay Output

♦ +3.3V Supply Operation

♦ 24-Pin TSSOP Package

MAX9476

Low-Jitter, 8kHz Reference

Clock Synthesizer Outputs 35.328MHz

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3530; Rev 0; 1/05

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

EVALUATION KIT

AVAILABLE

PART

PIN­PACKAGE

PKG

CODE

MAX9476EUG

24 TSSOP

U24-1

24

23

22

21

20

19

18

17

1

2

3

4

5

6

7

8

CLK1

GND

CLK2

V

DD

V

DDP

REIN

REO

TOP VIEW

CLK3

V

DD

GND

CLK4X2

V

DD

X1

GNDP

16

15

14

13

9

10

11

12

V

DD

CLK5

GND

CLK6SETI

LP1

LP2

GND

TSSOP

MAX9476

SHDN

Pin Configuration

MAX9476

CLK2

X1

CLK1

V

DDP

GNDP

X2

REO

CLK6

CLK5

CLK4

CLK3

GND

V

DD

LP1 LP2

REIN

R

SET

R

1

C

1

C

2

SETI

V

DD

SHDN

Typical Application Circuit

TEMP RANGE

-40°C to +85°C

MAX9476

Low-Jitter, 8kHz Reference
Clock Synthesizer Outputs 35.328MHz

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

DC ELECTRICAL CHARACTERISTICS

(VDD= V

DDP

= +3.0V to +3.6V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= V

DDP

= +3.3V, TA=

+25°C.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

VDDto GND...........................................................-0.3V to +4.0V

V

DDP

to GNDP.......................................................-0.3V to +4.0V

SHDN, REO, REIN, X1, X2, CLK_ to GND ...-0.3V to (VDD+ 0.3V)

LP1, SETI to GNDP.....................................-0.3V to (V

DD

+ 0.3V)
LP2 Internally Connected to GNDP

Short-Circuit Duration of Outputs ...............................Continuous

Continuous Power Dissipation (T

A

= +70°C)

24-Pin TSSOP (derate 12.2mW/°C above +70°C) .......976mW

Operating Temperature Range ...........................-40°C to +85°C

Maximum Junction Temperature .....................................+150°C

Storage Temperature Range .............................-60°C to +150°C

ESD Rating (Human Body Model) .......................................±2kV

Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER

CONDITIONS

UNITS

DIGITAL INPUTS (REIN, SHDN)

Input-High Logic Level V

IH

2.0 V

Input-Low Logic Level V

IL

0.8 V

Input-Current High Level I

IH

VIN = V

DD

20 µA

Input-Current Low Level I

IL

VIN = 0 -20 µA

DIGITAL OUTPUT CLOCKS (CLK1–CLK6, REO)

Output-High Logic Level V

OH

IOH = -4mA

V

Output-Low Logic Level V

OL

IOL = 4mA 0.4 V

POWER SUPPLY (VDD, V

DDP

)

Power-Supply Range V

DD

3.0 3.6 V

PLL Power-Supply Range V

DDP

3.0 3.6 V

Power-Supply Current

(Note 2) 9 16 mA

Shutdown Supply Current I

SHDN

7.5 30 µA

SYMBOL

MIN TYP MAX

VDD -

0.6V

IDD + I

DDP

MAX9476

Low-Jitter, 8kHz Reference

Clock Synthesizer Outputs 35.328MHz

_______________________________________________________________________________________ 3

Note 1: Specifications are 100% tested at TA= +25°C. Specifications over temperature are guaranteed by design and characterization.
Note 2: No load on clock outputs.
Note 3: Guaranteed by design.

Note 4: Crystal loading capacitance is 14pF.

AC ELECTRICAL CHARACTERISTICS

(VDD= V

DDP

= +3.0V to +3.6V, CL= 20pF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VDD= V

DDP

= +3.3V,

T

A

= +25°C.) (Note 3)

PARAMETER

CONDITIONS

UNITS

DIGITAL OUTPUT CLOCKS (CLK1–CLK6)

Frequency Range f

OUT

MHz

Clock Rise Time t

R1

20% to 80% V

DD

1.8 ns

Clock Fall Time t

F1

80% to 20% V

DD

1.8 ns

Duty Cycle 40 50 60 %

J

P1

Peak-to-peak 83 ps

Period Jitter

J

P2

RMS 4

ps

RMS

Output Skew t

S

Peak-to-peak

ps

REFERENCE CLOCK OUTPUT (REO)

Frequency f

REF

8 kHz

Clock Rise Time t

R2

1.8 ns

Clock Fall Time t

F2

1.8 ns

Duty Cycle 40 50 60 %

VCXO

Crystal Frequency f

XTL

MHz

Crystal Accuracy

Including frequency accuracy and
temperature range

ppm

VCXO Pulling Range (Note 4)

ppm

Input Reference CLK Pulse Width

t

W

Measured at high or low states 10 ns

SYMBOL

MIN TYP MAX

35.328

185

35.328

±25

-100 +100