SM8761 series
Spread Spectrum Clock Generator
OVERVIEW
The SM8761 series are compact clock generator ICs that have a spread spectrum (SS) function to reduce unde-
sirable EMI radiation. They have a built-in crystal oscillator circuit, PLL, and loop filter. They accept an input
clock signal, generated using an external crystal or direct external clock input, and output an SS-modulated
clock signal. In addition, versions are available for center spread and down spread modulation mode, and all
have a mode control pin to select the SS modulation function.
FEATURES
I
I
I
Spread spectrum clock output to reduce EMI
Correspond to wide range of output frequency
Low jitter
SM8761AA
I
I
I
Operating supply voltage: 3.3
±
0.3V
Multiplication: 1-time multiplication
Package: 8-pin SOP
SM8761AB
Center spread
±
0.75% to
±
2.25%
12MHz to 32MHz
12MHz to 32MHz
12MHz to 32MHz
1-time multiplication
200ps (typ) @16MHz
Spectrum modulation mode
Spectrum modulation rate
*1
Crystal element connection
Input frequency
External input clock
Output frequency
Multiplication
Jitter (Cycle-to-Cycle)
Down spread
– 1.0% to – 3.8%
20MHz to 40MHz
20MHz to 108MHz
20MHz to 108MHz
1-time multiplication
200ps (typ) @33MHz
120ps (typ) @75MHz
*1. The modulation rate that can be selected varies with the input frequency.
PINOUT
(Top view)
PACKAGE DIMENSIONS
(Unit: mm)
+
0.15
−
0.1
0.05
XT
VDD
VSS
CLKOUT
1
2
3
4
8
7
6
5
XTN
MSEL1
MSEL0
0.695typ
6.2
±
0.3
4.4
±
0.2
TSTN
5.2
±
0.3
0.05
±
0.05
1.5
±
0.1
1.27
0.4
±
0.2
APPLICATIONS
I
I
I
I
I
0.10
0.4
±
0.1
0 to 10°
0.12
M
Printer (laser/inkjet)
Photocopiers, scanners
LCD/PDP displays
Projectors
Miscellaneous electronic equipment
ORDERING INFORMATION
Device
SM8761AAS
SM8761ABS
Package
8-pin SOP
NIPPON PRECISION CIRCUITS INC.—1
NPC [ NIPPON PRECISION CIRCUITS INC ]
