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Module Data Sheet: VCT2000A 155.520MHz Application: LVPECL Output-Dual Input Clock Generator 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
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Rev. "7" 6/02/03
Module Data Sheet: VCT2000A 155.520MHz Application: LVPECL Output-Dual Input Clock Generator
FORCE FREE RUN FREE RUN STATUS ALARM REF A REF B Q Q
8 KHz PHASE ALIGNER
PHASE DET
LOW PASS ANALOG FILTER
LOW JITTER VCXO
SEL AB
f/N
OPTIONAL REFERENCE OUTPUT
ENABLE / TRISTATE
VCT2000A Block Diagram
2.0
2.1 2.2 2.3 2.4 2.4.1 2.4.2 2.5 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7 2.5.8 2.5.9 2.6 2.6.1 2.6.2 2.7 2.7.1 2.7.2
ELECTRICAL CHARACTERISTICS
Specification Regulated Input Supply Voltage, Vcc Supply Current Drain @ 3.5Vdc Frequency Output Temperature Ranges Operating Temp. Range Storage Temp. Range Timing Parameters Output Rise and Fall Time (20% 80%) Input Jitter Tolerance @ 8kHz Reference (Input Jitter Frequencies > 10 Hz) Acquisition Time (Offsetting reference by 20ppm) Jitter Filter Bandwidth Capture/pull-in range Free Run Frequency Output Duty Cycle Phase Transient due to Reference switching SONET Jitter BW 12 kHz - 20 MHz Input Logic Levels ` 0' `1' Output Logic Levels (into 50 @Vcc-2.0V) `0' `1' 155.520 Min 3.10 Typ 3.30 Max 3.50 110 Units V DC mA MHz
0 -40
70 85
C C
31.25 -25 -20 45
1 50
550 10 25 20 55 150 1
ps s s Hz ppm ppm % nS ps
-0.5 2.4
0.8 5.5
V V
Vcc-1.62 Vcc-1.02
V V
Rev. "7" 6/02/03
Page 2 of 5
Module Data Sheet: VCT2000A 155.520MHz Application: LVPECL Output-Dual Input Clock Generator
2.8 2.9 Dual Reference input (+/- 30ppm) Output loads @ Vcc-2.00V 8 50 kHz
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 #
1 2, 3, 14, 15 4 5 6 7 8, 17 9 10 11 12 13 16 18
Pin Name
ENABLE/TRI-STATE No Connection REFA SELA/B RESET REFB GND FRstatus Vcc Optional ALARM FR /Q Q
Pin Description
VCXO Enable (Enable = 0, Disable = 1 = CMOS Outputs Tri-stated) No Connection 8kHz CMOS Reference Frequency Input Input Reference Select Pin (REFA = 0, REFB = 1) RESET (RESET = 1) 8kHz CMOS Reference Frequency Input Ground Free Run Status (FR = 1) Supply Voltage Reserved for Optional Use Loss of Reference / Lock alarm (Alarm = 1) Force Free Run (Phase Lock = 0, Free Run = 1) LVPECL Complementary Output LVPECL Output
Page 3 of 5
Rev. "7" 6/02/03
Module Data Sheet: VCT2000A 155.520MHz Application: LVPECL Output-Dual Input Clock Generator
Dimensions for Pads
I/O Truth Table Inputs
Reset Enable/ Tri State SEL A/B REF A REF B Free Run Free Run Status Alarm
Outputs
Oscillator Output 8 kHz Output
1 X 0 0 0 0 0 0 0 0
0 1 0 0 0 0 0 0 0 0
X X X 0 1 0 0 1 0 X
X X X Ref A Available Not Available Not Available Not Available Ref A Available Ref A Available Not Available
X X X Ref B Available Ref B Available Ref B Available Ref B Available Not Available Not Available Not Available
X X 1 0 0 0 0 0 0 0
1 Tri state 1 0 0 0 0 0 0 1
X Tri State 1 0 0 0 1 1 0 1
X Free Run Free Run Ref A Lock Ref B Lock Free Run Free Run Free Run Ref A Lock Free Run
X Tri State Free Run Ref A Lock Ref B Lock Free Run Free Run Free Run Ref A Lock Free Run
Page 4 of 5
Rev. "7" 6/02/03
Module Data Sheet: VCT2000A 155.520MHz Application: LVPECL Output-Dual Input Clock Generator
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 +85C. 4.3 Humidity (non- Condensing) 85% Relative humidity max @ 40C. 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 >183C Time 6min 2.0min
>220C 0.5min
220C Max temperature
6.0
ALARM
Loss of Lock Alarm
Pin 1 Locator
Page 5 of 5
Rev. "7" 6/02/03

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