M685 Datasheet, PDF (1/7 Pages) Integrated Circuit Systems – DUAL SAW, SELECTABLE FREQUENCY VCSO

Preliminary Information
M685
DUAL SAW, SELECTABLE FREQUENCY VCSO
GENERAL DESCRIPTION
The M685 is a dual SAW, selectable frequency VCSO
frequency source for low-jitter clock
generation. An integrated SAW (surface
acoustic wave) delay line implements the
high-Q VCO (voltage controlled oscillator)
function, which results in low output phase
noise and very low jitter. The M685-01 is available in
a range of center frequencies from 125 to 177 MHz.
The M685-02 provides 500 to 708 MHz. Guaranteed
minimum pull-range of ±120 ppm meets GbE
requirements. (It also fully satisfies ±50 ppm minimum
pull-range specification commonly required.) Industry-
standard Kvco (VCO Gain) provides full replacement
compatibility. The M685 is well suited for phase-locked
loop implementations, clock and data recovery circuits,
and other timing applications in telecom and optical
fiber networking systems (e.g., OC-48).
FEATURES
◆ Two integrated SAW devices and selectable output
frequency; supports multi-rate optical interfaces
◆ M685-01 output frequencies from 125 to 177 MHz
M685-02 output frequencies from 500 to 708 MHz
(Specify center frequencies at time of order)
◆ Industry-standard Kvco for full compatibility
◆ Low phase jitter 0.2ps rms typical for the M685-02
(50kHz to 80MHz)
◆ Differential 3.3V LVPECL output
◆ Single 3.3V power supply
◆ Small 5 x 7.5mm SMT (surface mount) package
◆ Pb-free / Compliant to EC RoHS Directive
BLOCK DIAGRAM
M685
PIN ASSIGNMENT (5 x 7.5mm SMT)
M_M6₆8₈5₀
(Top View)
Figure 1: Pin Assignment
Sample of Available Output Frequencies
VCSO Center
Frequencies¹ (MHz)
Applications
155.5200, 167.3316 SONET/SDH, SONET/SDH FEC
156.2500, 161.1328
Gigabit Ethernet, GbE FEC
622.0800, 669.3266 SONET/SDH, SONET/SDH FEC
625.0000, 644.5313
Gigabit Ethernet, GbE FEC
Table 1: Sample of Available Output Frequencies
Note 1: Specify VCSO center frequencies at time of order
SAW Delay Line
VIN
VCSO
Phase
Shifter
SAW Delay Line
FOUT
nFOUT
VCSO
Phase
Shifter
F_SEL
Figure 2: Block Diagram
M685 Datasheet Rev 0.7
Revised 29Jul2009
M685 Dual SAW, Selectable Frequency VCSO
I n t e g r a t e d D e v i c e Te c h n o l o g y, I n c . ● C o m m u n i c a t i o n M o d u l e s ● w w w. i dt . c o m ● t e l ( 5 0 8 ) 8 5 2 - 5 4 0 0