Spread Spectrum Clock Generator
SM8761 series Spread Spectrum Clock Generator
OVERVIEW
The SM8761 series are compact clock generator ICs that have a sp...
Description
SM8761 series Spread Spectrum Clock Generator
OVERVIEW
The SM8761 series are compact clock generator ICs that have a spread spectrum (SS) function to reduce undesirable 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 www.DataSheet4U.com 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)
+ 0.1 0.15 −
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....
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