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M1025/26 Datasheet Rev 1.0
M1025/26 VCSO Based Clock PLL with AutoSwitch
Revised 28Jul2004
Integrated Circuit Systems, Inc.
●
Networking & Communications
●
www.icst.com
●
tel (508) 852-5400
M1025/26
VCSO B
ASED
C
LOCK
PLL
WITH
A
UTO
S
WITCH
Integrated
Circuit
Systems, Inc.
P r o d u c t D a t a S h e e t
G
ENERAL
D
ESCRIPTION
The M1025/26 is a VCSO (Voltage Controlled SAW
Oscillator) based clock jitter
attenuator PLL designed for clock
jitter attenuation and frequency
translation. The device is ideal for
generating the transmit reference
clock for optical network systems
supporting up to 2.5Gb data rates.
It can serve to jitter attenuate a
stratum reference clock or a recovered clock in loop
timing mode. The M1025/26 module includes a
proprietary SAW (surface acoustic wave) delay line as
part of the VCSO. This results in a high frequency,
high-Q, low phase noise oscillator that assures low
intrinsic output jitter.
F
EATURES
◆
Integrated SAW delay line; low phase jitter of < 0.5ps
rms, typical (12kHz to 20MHz)
◆
Output frequencies of 62.5 to 175 MHz
(Specify VCSO output frequency at time of order)
◆
LVPECL clock output (CML and LVDS options available)
◆
Reference clock inputs support differential LVDS,
LVPECL, as well as single-ended LVCMOS, LVTTL
◆
Loss of Lock (
LOL
) output pin; Narrow Bandwidth
control input (
NBW
pin)
◆
AutoSwitch (
AUTO
pin) - automatic (non-revertive)
reference clock reselection upon clock failure
◆
Acknowledge pin (
REF_ACK
pin) indicates the actively
selected reference input
◆
Hitless Switching (HS) options with or without Phase
Build-out (PBO) to enable SONET (GR-253) /SDH
(G.813) MTIE and TDEV compliance during reselection
◆
Pin-selectable feedback and reference divider ratios
◆
Single 3.3V power supply
◆
Small 9 x 9 mm SMT (surface mount) package
S
IMPLIFIED
B
LOCK
D
IAGRAM
P
IN
A
SSIGNMENT
(9 x 9 mm SMT)
Figure 1: Pin Assignment
Figure 2: Simplified Block Diagram
Example I/O Clock Frequency Combinations
Using
M1025-11-155.5200 or M1026-11-155.5200
Input Reference
Clock (MHz)
PLL Ratio
(Pin Selectable)
Output Clock
(MHz)
(Pin Selectable)
(M1025) (M1026)
19.44 or 38.88
77.76
155.52
622.08
(M1025) (M1026)
8 or 4
2
1
0.25
155.52
or
77.76
Table 1: Example I/O Clock Frequency Combinations
M1025
M1026
(Top View)
18
17
16
15
14
13
12
11
10
28
29
30
31
32
33
34
35
36
1
2
3
4
5
6
7
8
9
M
G
N
D
n
R
D
n
V
P_SEL0
P_SEL1
nFOUT
FOUT
GND
REF_ACK
AUTO
VCC
GND
MR_SEL2
MR_SEL0
MR_SEL1
LOL
NBW
VCC
DNC
DNC
DNC
n
O
V
n
n
O
G
G
G
1
2
2
2
2
2
2
2
2
FOUT
nFOUT
TriState
Loop Filter
PLL
Phase
Detector
R Div
MUX
0
REF_SEL
DIF_REF0
nDIF_REF0
1
P_SEL1:0
NBW
DIF_REF1
nDIF_REF1
Auto
Ref Sel
0
1
LOL
Phase
Detector
REF_ACK
AUTO
M1025/26
VCSO
P Divider
LUT
LOL
2
M Divider
4
M/R
Divider
LUT
MR_SEL3:0
P Divider
(1, 2, or TriState)