LTC6902

1

6902f

s

2-, 3- or 4-Phase Outputs

s

Optional Spread Spectrum Frequency Modulation

for Improved EMC Performance

s

5kHz to 20MHz Frequency Range

s

One External Resistor Sets the Frequency

s

One External Resistor Sets Percent Frequency

Spreading

s

400

s

Frequency Error

≤1.5% Max, 5kHz to 10MHz

s

Frequency Error

≤2% Max, 5kHz to 10MHz

s

±40ppm/°C Temperature Stability

s

Fast Start-Up Time: 50

µs to 1.5ms

s

100

Ω CMOS Output Driver

s

Operates from a Single 2.7V to 5.5V Supply

s

Available in 10-Lead MS Package

Multiphase Oscillator

with Spread Spectrum

Frequency Modulation

s

Switching Power Supply Clock Reference

s

Portable and Battery-Powered Equipment

s

PDAs

s

Cell Phones

s

Clocking Switched Capacitor Filters

The LTC

oscillator that provides multiphase outputs in a small

package. The oscillator frequency is set by a single exter-

spread spectrum frequency modulation (SSFM) capability

that can be activated and controlled by an additional

resistor and has a range of 100kHz and 20MHz. In order

to accommodate a wider output frequency range, a pro-

grammable divider (divide by 1, 10 or 100) is included.

The integrated programmable multiphase circuit pro-

vides either 2-, 3- or 4-phase waveforms.

The LTC6902’s SSFM capability modulates the oscillator’s

frequency by a pseudorandom noise (PRN) signal to

spread the oscillator’s energy over a wide frequency band.

This spreading decreases the peak electromagnetic radia-

tion level and improves electromagnetic compatibility

(EMC) performance. The amount of frequency spreading

is programmable by a single additional external resistor

, LTC and LT are registered trademarks of Linear Technology Corporation.

DIV

PH

OUT1

OUT2

OUT4

OUT3

OUT2

OUT1

SET

MOD

GND

OUT4

OUT3

LTC6902

5V

OPEN

6902 TA01

0.1

µF

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

500kHz, 4-Phase Clock with 20% Frequency Spreading

FREQUENCY (kHz)

–40

–20

0

6902 TA02

–60

–80

–100

400

450

550

600

500

OUTPUT

SPECTRUM

WITH 20%

SPREADING

OUTPUT

SPECTRUM

WITH SSFM

DISABLED

Output Frequency Spectrum With and Without SSFM