PRELIMINARY 1.0 Module Data Sheet: VCT2001A 77.760 MHz Application: HCMOS Output-Dual Input Clock Generator DESCRIPTION AND APPLICATION The VCT2001A 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 0.78” x 0.83” x 0.29” mounted on a castellated pin FR-4 board. 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-Statable 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: 0.78” x 0.83” x 0.29” • Surface Mount with Castellated Pins Page 1 Rev. “4” 3/28/03 PRELIMINARY Module Data Sheet: VCT2001A 77.760 MHz Application: HCMOS Output-Dual Input Clock Generator FREE RUN STATUS FORCE FREE RUN ALARM REF A REF B 8 KHz PHASE ALIGNER PHASE DET LOW PASS ANALOG FILTER LOW JITTER VCXO 19.440 MHz OSCILLATOR OUTPUT f/N SEL AB 8 KHz OUTPUT ENABLE / TRISTATE VCT2001A Block Diagram 2.0 ELECTRICAL CHARACTERISTICS 2.1 Specification Regulated Input Supply Voltage, Vcc 2.2 Supply Current Drain… @ 3.5V 2.3 Frequency Output 2.4 2.4.1 2.4.2 Temperature Ranges Operating Temp. Range Storage Temp. Range 2.5 Timing Parameters Output Rise and Fall Time (20% 80%) Input Jitter Tolerance @ 8kHz Reference (Input Jitter Frequencies > 10 Hz) Acquisition Time (Offsetting ref. 20ppm) Jitter Filter Bandwidth Capture/pull-in range Free Run Frequency Output Duty Cycle Phase Transient due to Reference switching (Rearrangement) 2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7 2.5.8 2.6 Min 3.10 Typ 3.30 Max 3.50 55 77.760 0 -40 Units V DC mA MHz 70 85 ºC ºC 2 - 3 - ns µs -25 -20 45 1 50 10 25 20 55 50 s Hz ppm ppm % nS 2.6.1 2.6.2 Input Logic Levels ‘ 0’ ‘1’ -0.5 2.4 0.8 5.5 V V 2.7.1 2.7.2 Output Logic Levels (into 30pF load) ‘0’ ‘1’ -0.25 4.0 0.8 Vcc*0.9 V V 2.7 2.8 Dual Reference input (HCMOS levels) 8 kHz 2.9 Output load 10 pF Page 2 Rev. “4” 3/28/03 PRELIMINARY 3.0 Module Data Sheet: VCT2001A 77.760 MHz Application: HCMOS Output-Dual Input Clock Generator MECHANICAL CHARACTERISTICS Pkg. size is 0.780 in (25.40 mm) X 0.830in (26.67 mm) X 0.35 in (8.13 mm) max on an FR4 board with castellated pins. The module coplanarity is .004 in. (0.101 mm) Pin Descriptions Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Page 3 Pin Name 8 kHz Out N/C N/C GND F/R Alarm REF B REF A RF Output F/R status Vcc N/C Reset REFSEL Description Filtered 8 kHz Output Ground Force Free Run Input(“1” is Free Run) Alarm Output (1 = Alarm) 8kHz CMOS Reference Frequency Input 8kHz CMOS Reference Frequency Input Oscillator Output Free Run Status Output (FR = 1) Input Voltage-3.3V nominal Reset / Tri-State (1 = Reset) Reference Select A/B Input (A = 0, B = 1) Rev. “4” 3/28/03 PRELIMINARY Module Data Sheet: VCT2001A 77.760 MHz Application: HCMOS Output-Dual Input Clock Generator Dimensions for Pads I/O Truth Table Inputs Outputs Reset/ Tri State SEL A/B REF A REF B Free Run Free Run Status Alarm Oscillator Output 8 kHz Output 1 0 0 X X 0 Tri state 1 0 Tri State 1 0 Free Run Free Run Ref A Lock Tri State Free Run Ref A Lock 1 0 0 0 Ref B Lock Ref B Lock 0 0 0 0 0 Free Run Free Run 0 0 0 0 1 Free Run Free Run 0 1 0 0 1 Free Run Free Run 0 0 0 0 0 Ref A Lock Ref A Lock 0 X X X Ref B Available Ref B Available Ref B Available Ref B Available Not Available Not Available Not Available X 1 0 0 X X Ref A Available Not Available Not Available Not Available Ref A Available Ref A Available Not Available 0 1 1 Free Run Free Run Page 4 Rev. “4” 3/28/03 PRELIMINARY Module Data Sheet: VCT2001A 77.760 MHz Application: HCMOS 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 4.2 Storage Temperature 4.3 Humidity (non- Condensing) 4.4 Atmospheric Pressure 4.5 Vibration 4.6 Shock 5.0 6.0 0 to +70 °C. -40 to +85°C. 95% Relative humidity max @ 40°C. 730 to 780 mm Hg. 10 to 60 Hz with double amplitude of 1.52mm max. (1/2 hour in each of 3 perpendicular planes). 1/2 sine pulse, 7000G, with pulse width 0.3mSec. (1 shock in each of 6 directions of 3 perpendicular planes). MAXIMUM SOLDERING PROFILE Temperature 110 to150 °C >183°C Time 6min 2.5min >235°C 0.25min 240°C Max temperature ALARM SITUATIONS Loss of Reference Situation Loss of Lock Situation Page 5 Rev. “4” 3/28/03