LTC6902

5

6902f

Output Operating at 20MHz,

1V/DIV

12.5ns/DIV

69012 G06

1V/DIV

25ns/DIV

69012 G07

Output Operating at 10MHz,

0V

0V

TYPICAL PERFOR A CE CHARACTERISTICS

QUICK DESIG GUIDE

Step 1. Select Multiphase Mode, Setting M

By selecting the multiphase mode, a division parameter M

is also chosen:

2-Phase: Connect PH Pin to GND

M = 1

3-Phase: Leave PH Open

M = 3

4-Phase: Connect PH Pin to V+

M = 4

Step 2. Choosing Programmable Divider Setting N

A. For applications using spread spectrum frequency

modulation (SSFM) or applications that are constant fre-

quency where low clock jitter is the primary specification:

DIVIDER SETTING

N = 1

Connect DIV Pin to GND

2MHz to 20MHz

N = 10

Leave DIV Open

200kHz to 2MHz

N = 100

< 200kHz

Note: The frequency range numbers are for a 5V supply where a 20MHz

output is the maximum frequency supported. For low supply applications

(2.7V

of the above numbers should be halved.

B. For constant frequency applications where frequency

accuracy is the primary specification:

DIVIDER SETTING

N = 1

Connect DIV Pin to GND

> 500kHz*

N = 10

Leave DIV Open

50kHz to 500kHz

N = 100

< 50kHz

10MHz for low supply applications (2.7V

f

MHz

NM

k

R

kHz

f

MHz

Spreading Percentage

R

R

OUT

SET

OUT

SET

MOD

=•

Ω









≤≤

=

10

20

520

20

•

•

;

DIV

PH

OUT1

OUT2

OUT4

OUT3

OUT2

OUT1

SET

MOD

GND

OUT4

OUT3

LTC6902

DIV

PH

6902 F01

0.1

µF

Figure 1. Typical Application with Design Equation