LTC6902 Linear Technology, LTC6902 Datasheet - Page 5

• Manufacturer Part Number: LTC6902
• Description: Multiphase Oscillator
• Manufacturer: Linear Technology

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QUICK DESIG GUIDE
Step 1. Select Multiphase Mode, Setting M
By selecting the multiphase mode, a division parameter M
is also chosen:
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:
TYPICAL PERFOR A CE CHARACTERISTICS
2-Phase: Connect PH Pin to GND
3-Phase: Leave PH Open
4-Phase: Connect PH Pin to V+
DIV
1V/DIV
PH
0.1 F
0V
Output Operating at 20MHz,
V
V
V
S
+
+
U
= 5V
= 5V, R
V
DIV
PH
OUT1
OUT2
+
LTC6902
R
R
SET
W
MOD
SET
OUT4
OUT3
= 10k, C
MOD
GND
SET
12.5ns/DIV
U
L
= 10pF
Figure 1. Typical Application with Design Equation
M = 1
M = 3
M = 4
6902 F01
OUT4
OUT3
OUT2
OUT1
69012 G06
f
Spreading Percentage
OUT
DIVIDER SETTING
N = 1
N = 10
N = 100
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 V
of the above numbers should be halved.
B. For constant frequency applications where frequency
accuracy is the primary specification:
DIVIDER SETTING
N = 1
N = 10
N = 100
*The maximum frequency (f
10MHz for low supply applications (2.7V V
10
1V/DIV
N M
MHz
0V
•
+
Output Operating at 10MHz,
V
V
Connect DIV Pin to GND
Leave DIV Open
Connect DIV Pin to V
Connect DIV Pin to GND
Leave DIV Open
Connect DIV Pin to V
S
4V), the maximum rated output frequency is 10MHz and all
+
= 3V
= 3V, R
20
R
SET
SET
k
= 20k, C
25ns/DIV
OUT
20
;
L
5
= 10pF
• M) is 20MHz for 5V applications and is
•
kHz f
+
+
R
R
MOD
SET
FREQUENCY RANGE (f
FREQUENCY RANGE (f
OUT
+
69012 G07
4V).
50kHz to 500kHz
200kHz to 2MHz
2MHz to 20MHz
20
> 500kHz*
LTC6902
< 200kHz
< 50kHz
MHz
OUT
OUT
• M)
• M)
5
6902f