Module Data Sheet: VCT2000A 155.520MHz
Application: LVPECL Output-Dual Input Clock Generator
Page 1 of 5
Rev. "7" 6/02/03
1.0
DESCRIPTION AND APPLICATION
The VCT2000A is a dual reference input 3.3V clock generator module with an
HCMOS output. Reference inputs are selectable by a one-bit select control input.
An alarm output can be used to detect a problem on the selected reference, such as
a loss of lock or a loss of reference. A logic level "1" is indicated from the alarm pin
when there is a problem with the selected reference. The unit operates in the free run
mode when there is a problem with the selected reference, or when free run is invoked by
enabling the forced free run input. Free run accuracy will keep the output to within 20
ppm. The reference will not automatically switch upon loss of reference. Also, all
outputs may be tri-stated for external testing purposes with a signal to the Tri-State/Reset
input.
The Loss of Reference alarm detects a missing rising edge within 100 nS of the
missing edge. This is usually around 70 nS.
The 8kHz output is divided from the on-board low jitter oscillator. Output phase
coherence is maintained during reference switching rearrangement, so the output phase
will not necessarily be the same as the reference being used.
The dimensions of the low jitter module are 1.00" x 1.05" x 0.32" mounted on a
FR-4 board with castillations.
FEATURES:
Output jitter below 1 ps from 12 kHz to 20 MHz
Two Selectable References @ 8 kHz
Alarm Output Detecting Loss of Reference or Loss of Lock
Tri-State-able Outputs
Force Free-Run Function
Automatic Free Run Operation upon loss of both references
Rising Edge Phase Detector allows for any Duty Cycle Reference Input
3.3 Volt Regulated Power Supply
Small Size: 1 in (25.40 mm) X 1.05 in (26.67 mm) X 0.32 in (8.13 mm)
Surface Mount with Castillated Pins
Module Data Sheet: VCT2000A 155.520MHz
Application: LVPECL Output-Dual Input Clock Generator
Page 2 of 5
Rev. "7" 6/02/03
ALIGNER
8 KHz
REF A
SEL AB
ENABLE / TRISTATE
REF B
PHASE
FORCE FREE RUN
LOW PASS
DET
PHASE
f / N
FILTER
ANALOG
LOW
Q
VCXO
JITTER
OPTIONAL
REFERENCE
OUTPUT
Q
ALARM
FREE RUN STATUS
VCT2000A Block Diagram
2.0
ELECTRICAL CHARACTERISTICS
Specification Min Typ Max Units
2.1
Regulated Input Supply Voltage, Vcc
3.10
3.30
3.50
V DC
2.2
Supply Current Drain @ 3.5Vdc
110
mA
2.3
Frequency Output
155.520
MHz
2.4 Temperature
Ranges
2.4.1
Operating Temp. Range
0
70
C
2.4.2
Storage Temp. Range
-40
85
C
2.5 Timing
Parameters
2.5.1 Output Rise and Fall Time (20% 80%)
-
-
550
ps
2.5.2 Input Jitter Tolerance @ 8kHz Reference
(Input Jitter Frequencies > 10 Hz)
31.25 - - s
2.5.3 Acquisition Time (Offsetting reference by 20ppm)
-
1
-
s
2.5.4 Jitter Filter Bandwidth
-
-
10
Hz
2.5.5 Capture/pull-in range
-25
-
25
ppm
2.5.6 Free Run Frequency
-20
-
20
ppm
2.5.7 Output Duty Cycle
45
50
55
%
2.5.8 Phase Transient due to Reference switching
150
nS
2.5.9 SONET Jitter BW 12 kHz - 20 MHz
1
ps
2.6
Input Logic Levels
2.6.1 ` 0'
-0.5
0.8
V
2.6.2 `1'
2.4
5.5
V
2.7
Output Logic Levels (into 50
@Vcc-2.0V)
2.7.1 `0'
Vcc-1.62
V
2.7.2 `1'
Vcc-1.02
V
Module Data Sheet: VCT2000A 155.520MHz
Application: LVPECL Output-Dual Input Clock Generator
Page 3 of 5
Rev. "7" 6/02/03
2.8
Dual Reference input (+/- 30ppm)
8
kHz
2.9
Output loads @ Vcc-2.00V
50
3.0
MECHANICAL CHARACTERISTICS
Pkg. size is 1 in (25.40 mm) X 1.05 in (26.67 mm) X 0.32 in (8.13 mm) max on an FR4 board
with castellated pins. Overall coplanarity is .004 in (0.101mm).
VCT2000A Outline and Dimensions
Pin Descriptions
Pin #
Pin Name
Pin Description
1
ENABLE/TRI-STATE VCXO Enable (Enable = 0, Disable = 1 = CMOS Outputs Tri-stated)
2, 3, 14,
15
No Connection
No Connection
4
REFA
8kHz CMOS Reference Frequency Input
5
SELA/B
Input Reference Select Pin (REFA = 0, REFB = 1)
6
RESET
RESET (RESET = 1)
7
REFB
8kHz CMOS Reference Frequency Input
8, 17
GND
Ground
9 FRstatus
Free Run Status (FR = 1)
10 Vcc
Supply Voltage
11
Optional
Reserved for Optional Use
12
ALARM
Loss of Reference / Lock alarm (Alarm = 1)
13
FR
Force Free Run (Phase Lock = 0, Free Run = 1)
16
/Q
LVPECL Complementary Output
18
Q
LVPECL Output
Module Data Sheet: VCT2000A 155.520MHz
Application: LVPECL Output-Dual Input Clock Generator
Page 4 of 5
Rev. "7" 6/02/03
Dimensions for Pads
I/O Truth Table
Inputs
Outputs
Reset Enable/
Tri State
SEL
A/B
REF A
REF B
Free
Run
Free Run
Status
Alarm Oscillator
Output
8 kHz Output
1 0
X
X X
X
1 X X X
X 1
X
X
X
X
Tri state
Tri State
Free Run
Tri State
0 0
X
X
X
1
1
1
Free Run
Free Run
0 0
0
Ref A
Available
Ref B
Available
0
0
0
Ref A Lock
Ref A Lock
0 0
1
Not
Available
Ref B
Available
0
0
0
Ref B Lock
Ref B Lock
0 0
0
Not
Available
Ref B
Available
0
0
0
Free Run
Free Run
0 0
0 Not
Available
Ref B
Available
0
0
1
Free Run
Free Run
0 0
1 Ref
A
Available
Not
Available
0
0
1
Free Run
Free Run
0 0
0 Ref
A
Available
Not
Available
0
0
0
Ref A Lock
Ref A Lock
0 0
X Not
Available
Not
Available
0
1
1
Free Run
Free Run
Module Data Sheet: VCT2000A 155.520MHz
Application: LVPECL Output-Dual Input Clock Generator
Page 5 of 5
Rev. "7" 6/02/03
4.0
STANDARD ENVIRONMENTAL LIMITS
This product is capable of operating within the following environmental conditions:
4.1 Operating Temperature
0 to +70
C.
4.2 Storage Temperature
-40 to +85
C.
4.3 Humidity (non- Condensing)
85% Relative humidity max @ 40
C.
4.4 Atmospheric Pressure
730 to 780 mm Hg.
4.5 Vibration
10 Gs 10 to 500 Hz with double amplitude of
1.52mm
max.
4.6
Shock
100G,
with
pulse
width
1mSec.
(1 shock in each of 6 directions of 3
perpendicular
planes).
5.0
MAXIMUM SOLDERING PROFILE
Temperature
110
to150
C >183
C
>220
C 220
C
Time
6min
2.0min 0.5min Max
temperature
6.0 ALARM
Loss of Lock Alarm
Pin 1 Locator
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