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Datum X72 Designers Reference Handbook

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Designer' s Reference
C/O/106031/I

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Summary of Contents for Datum X72

  • Page 1 Designer’ s Reference C/O/106031/I...
  • Page 2 Other trademarked terms may appear in this document as well. They are marked on first usage. Warranty Datum provides a 1 year warranty on the electronics and a 20 year warranty on the rubidium lamp and cell of this product.

  • Page 3: Table Of Contents

    3.1 Mechanical Considerations..................9 3.1.1 Recommended Mating Connectors .............. 9 3.1.2 Mounting Recommendations ................ 9 3.1.3 Integrating the X72 into a System .............. 10 3.1.3.1 Edge Boards ..............10 3.1.3.2 Standard Edge Board ............11 3.1.3.3 The Anchored Edge Board ..........12 3.1.3.4 3.25 Inch - Connector .............
  • Page 4 4.5 Maintenance ..................27 4.4.1 Repairs ..................27 4.5.2 Warranty ..................28 APPENDIX A X72 J1 Connector and Plug ......................A1-3 APPENDIX B Using the Datum Serial Interface Protocol ................... B1-10 APPENDIX C Using the X72 Developer's Kit ..................... C1-14...
  • Page 5 Marketing department during the design process. Scope1 This material consists of a brief description of X72 design supported by block diagrams, description of environmental issues, installation guidelines, required mating connectors, and unit operation. This document is available in both a hardcopy and in Adobe Acrobat Reader (.pdf) electronic format.
  • Page 6 Provides general information about this document, the intended audience, organization and contents. • Section 2: X72 Introduction and Overview This section contains a description of the X72 and lists its typical applications. Dimensions, performance and connector pinouts are documented. • Section 3: X72 Design Integration Considerations...

  • Page 7: Description

    2.0 Description The elevated operating temperature range of the The X72 rubidium oscillator is the newest and X72 sets a new high-point for this type of atomic smallest of DATUM’s family of precision frequency reference. Compared with traditional quartz oscil- generator components.
  • Page 8 The protocol used is difference between the input and the 1 PPS gener- Datum's proprietary Datum Serial Interface ated by the X72 through the RS232 link. Protocol, or DSIP. For simple applications the X72 provides a 5V The simplified block diagram below shows the...
  • Page 9 NOTE: all pins must be connected! Bottom View 2.07 (52.5) Front View 0.42 (10.6) Figure 2-3. Outline Drawing, X72 unit Table 2-1. J1 Connector Interface PIN# SIGNAL NAME TYPE** SIGNAL FUNCTION 1 - 7 +Power input (+4.5 to 5 Vdc or +10 to +32 Vdc).
  • Page 10 Rubidum Oscillator TABLE 2-2. X72 Design Absolute Maximum Ratings Symbol CHARACTERISTIC -40 Degrees C to 85 C UNITS (Unit in ambient still air – convection) Base-plate SUPPLY RELATIVE 5 VOLT UNIT -0.25 to 8 TO GROUND Table 1: ABSOLUTE MAXIMUM RATINGS...
  • Page 11 Rubidum Oscillator TABLE 2-3. X72 Design Operating Characteristics Symbol CHARACTERISTIC -40 Degrees C to 85 C UNITS (Unit in ambient still air - convection) Base-plate DIGITAL INPUTS/OUTPUTS SUPPLY RELATIVE 5 VOLT UNIT TO GROUND 10 TO 32 VOLT UNIT HIGH LEVEL INPUT...
  • Page 12 Figure 2-5. Total X72 Quiesent Power Dissipation, Typical (free convection) To be added when available Baseplate Temperature (deg C) Figure 2-6. Representative X.72 ∆f/f versus Temperature (uncompensated) Refer to the X72 Performance Characteristics document for more detailed information. X72 Designer's Reference 09-08-2001 C/O/106031G...

  • Page 13: Mechanical Considerations

    3.1.1 Mounting Recommendations The X72 may be mounted to a circuit card or chassis using the four mounting holes located at the corners of its baseplate. An interface cable or adapter card is required to access the X72 outputs and to interface with a host system.

  • Page 14: Integrating The X72 Into A System

    X72 and can mount which ever connectors are necessary for their application. This opens the X72 up to nearly any connection scheme. The examples included in this document are just a few of the integration methods possible with these edge boards.

  • Page 15: Standard Edge Board

    X72 Rubidium Oscillator 3.1.3.2 Standard Edge Board - PN 106569-003 The Standard version is intended for implementations where the Edge Board is connected directly into the system board by soldering directly to the PCB or plugging into a socket provided by the user (see example below).

  • Page 16: The Anchored Edge Board

    X72 Rubidium Oscillator 3.1.3.3 The Anchored Edge Board - PN 106569-002 The Anchored Edge Board can be used in applications where the Edge Board is not plugged into a PCB and does not have a solid electrica1 connection like a soldered header that can keep the Edge Board in place in harsh vibration environments.

  • Page 17: Inch - Connector

    X72 Rubidium Oscillator 3.1.3.4 3.25 - Connector - PN 060031-001 The 3.25 inch connector has been discontinued as a board connection option for the X72. 05-31-2002 X72 Designer’s Reference C/O/106031I...

  • Page 18: X72 - Lpro Adapter

    Low-Profile Rubidium Oscillator, is the most widely produced rubidium oscillator in the world, and has been designed into hundreds of applications. The X72-LPRO Adapter allow these customers to upgrade to the X72 without changing the physical interface in their unit.

  • Page 19: Thermal Considerations

    It is also very important to maintain a uniform temperature into the base- plate of the X72 through its mounting points. The X72 unit will operate normally without use of thermal tape, but for some field applications the tape may simplify customer system thermal design requirements.

  • Page 20: External Interfaces And Grounding

    3.4.1.1 RF Output Impedance versus Frequency The active rf output impedance for X72 is a nominal 50 ohms at 10 MHz, but is a widely varying impedance at other frequencies. This would have to be taken into consideration if the X72 rf output is driving a non-buffered filter.

  • Page 21: Transformer-Coupled Rf Load

    3.4.2 X72 1 PPS Input and Output The 1 PPS output signal of the X72 unit is positive edge triggered and gated with the rising edge of the clock. It’s duration for a 10 MHz unit is 400 ns ±10%. Rise/fall time is 4 ns.

  • Page 22: X72 Frequency Control Signal

    2.5V. This input can also be turned off completely elimi- nating any source of noise via the DSIP. In some versions of the X72, this function can be turned off by customer request on power up. If it is to be used later it would have to be enabled through the DSIP interface (refer to Appendix B).
  • Page 23 Changing less than +2˚C/minute baseplate temperature should result in negligible transients from mismatches. In addition, the X72 can be ordered with an internal temperature compensation option which achieves better temperature performance over the entire operating range. X72 Designer’s Reference...

  • Page 24: Modifiable Unit Settings

    X72 Rubidium Oscillator 3.6 Modifiable Unit Settings Some features of the X72 operation are modifiable by the customer. Refer to the X72 Developer’s Kit document (DK/106031) for information on how to use the DSIP interface to use these functions. 3.6.1 Hardware Selectable Items (default power up conditions cannot be altered) FXO Enable - user can turn the XO frequency output on or off with this command.

  • Page 25: Emi Considerations

    3.8.1 Input Filtering If filtering is added at the input connector of the X72, it cannot have any resonance points greater than the specified impedance. This would result in peaking the potential for detrimental oscillations.

  • Page 26: X72 Reliability And Maintenance

    3.9 X72 Reliability and Maintenance 3.9.1 X72 Reliability The X72 is designed with a goal of twenty years of operation without retuning. In order to accom- plish this, the major mechanisms impacting the need for maintenance were addressed. Thus, each...

  • Page 27: X72 Installation

    4.1 X72 Installation 4.1.1 Site Selection The X72 may be mounted in any orientation. In environments that approach the operating limits of the X72, the designers should take care to ensure tht the temperature limits are not exceeded. The X72 should not be installed in locations subjected to strong magnetic fields from transformers or large power supplies.

  • Page 28: Start-Up Sequence

    – Figure 4-1. Suggested Connections for X72, Initial Turn-on. Once the X72 is plugged in and is receiving power, wait 3 to 4 minutes while the unit achieves atomic lock. During this period, the monitored LOCK signal should be HIGH.
  • Page 29 X72 Rubidium Oscillator Dialog OK ~ 1 second Serial Interface Mute maximum ~ 17 W Interval varies based on Quiescent Operation temperature Level varies from 5 W to 15 W of unit at turn-on. Typically ~ 4.5 W depending on temperature of unit.

  • Page 30: Theory Of Operation

    X72 Rubidium Oscillator 4.3 Theory of Operation The Model X72 makes use of the atomic resonance property of rubidium ( Rb) to control the frequency of a quartz crystal oscillator via a frequency-locked loop (FLL). The FLL function block is shown in Figure 2-1. A microwave signal is derived from a voltage- controlled crystal oscillator (VCXO)and applied to the Rb vapor within a glass cell.

  • Page 31: Troubleshooting

    X72 Rubidium Oscillator 4.4 Troubleshooting If, after installation the X72 unit fails to provide outputs, or the rubidium oscillator fails to achieve lock, check the following: •. Is the external power supply providing power? • Is the external power supply providing the correct power? •...

  • Page 32: Maintenance

    4.5.1 Repairs The X72 is not field repairable, but some firmware upgrades can be done in the field, as noted in Section 2.4.. If the unit should fail, do not remove the cover of the unit and attempt to make repairs.

  • Page 33: Warranty

    4.5.2 X72 Warranty Datum warrants the X72 Electronics for 1 year, and the Rb lamp bulb & resonator cell for 20 years. Datum also warrants that at the time of shipment the X72 will be free from defects in materials furnished and workmanship performed by the Datum.

  • Page 34: X72 J1 Connector And Plug

    APPENDIX A X72 J1 Connector and Plug X72 Designer's Reference 09-08-2001 C/O/106031G...
  • Page 35 Figure A1: Molex Conector X72 Designer's Reference 09-08-2001 C/O/106031G...
  • Page 36 Figure A2: Molex Conector Plug Assembly X72 Designer's Reference 09-08-2001 C/O/106031G...
  • Page 37 X72 Connector Cable Connector 15uF D_OUT SERVICE R594D CFIELD D_IN 1PPS_IN 1PPS_OUT LOCK XTAL_OUT ACMOS_GND ACMOS_OUT RF_GND SINE_OUT 0805 SCHEMATIC, X72 ADAPTER. G.P. 390pF MMCX 0805 Figure A-3: X72 Edge Board Pinout Comparison X72 Designer's Reference 09-08-2001 C/O/106031G...
  • Page 38 WIRING CHART WIRING DIAGRAM NOTE: PINS 25 & 26 TWISTED 3 TURNS/INCH Figure A-4: X72 3.25" Interface Cable Connections X72 Designer's Reference 09-08-2001 C/O/106031G...
  • Page 39 Figure A-5: X72 Layout Drawing for Edge Boards X72 Designer's Reference 09-08-2001 C/O/106031G...

  • Page 40: Using The Datum Serial Interface Protocol

    X72 Rubidium Oscillator APPENDIX B Using the Datum Serial Interface Protocol X72 Designer’s Reference Manual 09-08-2001 DK/106031G...
  • Page 41 X72 Rubidium Oscillator Table of Contents 1.0 Using the Datum Serial Interface Protocol ............. 3 1.1 Host Terminal Emulator Setup ................ 3 1.2 Data Format ................... 3 1.2.1 Run Mode Data Format (Customer Mode) ........3 1.2.2 Factory Mode ................... 7 1.2.3 Floating Point Number Representation..........
  • Page 42 Do not convert data to decimal when transmitting to the X72. All data are sent to the X72 and received back as “ASCII Coded Hex”. The following example shows how data are encoded.
  • Page 43 X72 Rubidium Oscillator Example of output from unit. Example 1 (actual unit output) Example of output from X72 after power applied to the unit. X72 by Datum, Inc., Copyright 2001 SDCP Version 3.75 of 3/2001; Loader Version 2 Mode CNN1...
  • Page 44 Ctl Reg: 029C, Res temp off: BFC53F7D, lamp temp. off: c0074FOE, FC: enabled, Srvc: low —————————————————————————————————————- The following print out is an example of entering the letter “h” to get the “help menu” from the X72: r>h a: Set FC Mode...
  • Page 45 X72 Rubidium Oscillator The following print out shows the response to the command for “w” for X72 “Health Data” (wellness): r>w AData: SCont: 6012 SerNum: 18C PwrHrs: 18A PwrTicks: 11A6848 LHHrs: 17E LHTicks: 83DBD0 RHHrs: 17E RHTicks: 83D2E3 dMP17: 41883621...
  • Page 46 X72 Rubidium Oscillator 1.2.2 Factory Mode Data output from the X72 in factory mode is not intended for user outside the factory and is not described in this document beyond Table 1-4. CAUTION: use of factory mode could result in the erasure of firmware on the X72, rendering it inoperable, making it necessary to return it to the factory for re-programming.
  • Page 47 Table B-3 defines the bit functions of the factory mode commands of the X72. Table B-4 defines the administrative mode commands. Table B-5 defines the bit functions and controlling agent of the output control register of the X72. Table B-2. X72 Run Mode Commands...
  • Page 48 NOTE: This mode and ADMIN mode allow the loading of new code or updates, or reconfiguring defaults in the field. It is not a normal operating mode. Table B-4. X72 Administrative Mode Commands USER OUTPUT TO X72 RESPONSE TO HOST NAME &...
  • Page 49 X72 Rubidium Oscillator The output control status register (OSR) bit structure, control features and controlling factors are defined as shown below. Table B-5. X72 Output Control Status Register Structure Bit # Control Description Controller 0. * Lamp Switch Power Boost 0 = Lamp Switch off –...

  • Page 50: Using The X72 Developer's Kit

    X72 Rubidium Oscillator APPENDIX C Using the X72 Developer’s Kit X72 Designer’s Reference Manual 09-20-2001 DK/106031G...
  • Page 51 X72 Rubidium Oscillator Table of Contents ................3 1.0 Introduction 2.0 Turn-on Procedure ................... 4 3.0 Start-up Sequence ................... 7 4.0 The Datum X72 Development Kit Hardware ............8 X72 Designer’s Reference Manual 09-20-2001 DK/106031G...
  • Page 52 Power: NOTE: The X72 provided in the Developer’s Kit operates on 10 to 32 Vdc. The X72 unit included in the kit is configured at the factory to operate at 10 to 32 Vdc; a 5V version of the X72 is also available (jumpers on the Developer’s Kit board must be added - refer to Figure 1-5).
  • Page 53 • Verify that the X72 is mounted to the heat sink supplied or to a customer supplied heat sink device. • Verify the X72 voltage option (5V or 10-32Vdc), if a different power supply is used from what is supplied with the kit.
  • Page 54 PRFS portable rubidium frequency standard and the FMS-2000 frequency measurement system. Figure 1-2 is a top view of the X72 case. Figure 1-3 is a diagram of the baseplate showing mounting holes. Table 1-1 provides signal information for the J1 connector.
  • Page 55 X72, an external series resistor may be required 0.42 (10.6) on pin 11 to prevent Front View overvoltage damage. Figure 1-3. Outline Drawing, X72 unit Table 1-1. J1 Connector Interface PIN# SIGNAL NAME TYPE** SIGNAL FUNCTION 1 - 7 VDD (bundled)
  • Page 56 After 7.5 minutes the accuracy of the X72 oscillator will be at <1E-9. Aging and temperature coefficient performance of the X72 unit will vary according to the application profile specified by the customer at time of order. Refer to the X72 product specifica- tion for information on application profiles and unit performance.
  • Page 57 NOTE: 10 - 32 Vdc is the recommended method of operation To use the DSIP firmware of the X72, connect the serial port of the interface test board to a host PC com port (this cable is supplied by the customer). Refer to Section 4.0 for information on DSIP commands and responses.
  • Page 58 * These two jumpers are the standard configuration. Remove B and place jumper on Jumper Location C and solder wire at D to enable 5V operation. for 5V Operation X72 ADAPTER TEST BOARD Interface Cable 3' P/N 106452-001 P/N 060032-001 X72 UNIT...
  • Page 59 (Supplied) 390pf For tests involving measurements of the Spur and Sine Amplitude Output, the Datum supplied 3.25" cable must be used with a customer supplied 390pf Capacitor for optimization of the signal. The capacitor must be connected as shown in the diagram above. This capacitor is not required for the 3' cable.
  • Page 60 Datum 3 Parker In U.S.A. 1-800-337-2866 Irvine, CA 92618-1605 (949) 598-7600 F AX: (949) 598-7650...

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