Microchip Technology 8040C User manual

 2021 Microchip Technology Inc. and its subsidiaries DS50003206A
8040C/8040CLN
User’s Guide
Rubidium Frequency Standard

DS50003206A-page 2
 2021 Microchip Technology Inc. and its subsidiaries
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ISBN: 978-1-5224-9036-4
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please visit www.microchip.com/quality.

8040C/8040CLN USER’S GUIDE
DS50003206A-page 3
Preface
OVERVIEW
The internal rubidium reference oscillator on the 8040C/8040C LN product was
changed from the SA22C to the SA55 in 2021. PCN0031 specifies model revisions
affected by this change (included in Appendix A. “PCN00031”). Appendix
B. “Revised Information Due to Implementation of SA55” details differences in
functionality. The original functionality with the SA22C has been preserved in the man-
ual for historical purposes. Users should always verify the revision of the unit located
on the serial number label on the rear panel of the instrument to determine which inter-
nal reference and relevant instructions apply. A note has been included on any para-
graph where an update applies.
PURPOSE OF THIS GUIDE
The 8040C/8040CLN User’s Guide describes the procedures for unpacking, installing,
using, maintaining the 8040C/8040CLN. Please review the most recent copy of the
datasheet:
https://www.microsemi.com/document-portal/doc_download/133415-rubidium-8040c-
datasheet
WHO SHOULD READ THIS GUIDE
This document is intended for engineers and telecommunications professionals who
are designing, installing, operating, or maintaining time, frequency, and synchroniza-
tion systems having a requirement for a low profile and highly precise frequency gen-
erator. To use this document effectively, you should have a good understanding of
digital telecommunications technologies and analog frequency generation and synthe-
sis techniques.
DOCUMENT LAYOUT
This guide contains the following sections:
•Chapter 1. “Introduction”: Provides an overview of the product, equipment
purpose, and factory configurations.
NOTICE TO CUSTOMERS
All documentation becomes dated, and this manual is no exception. Microchip tools and
documentation are constantly evolving to meet customer needs, so some actual dialogs
and/or tool descriptions may differ from those in this document. Please refer to our website
(www.microchip.com) to obtain the latest documentation available.
Documents are identified with a “DS” number. This number is located on the bottom of each
page, in front of the page number. The numbering convention for the DS number is
“DSXXXXXXXXA”, where “XXXXXXXX” is the document number and “A” is the revision level
of the document.
For the most up-to-date information on development tools, see the MPLAB® IDE online help.
Select the Help menu, and then Topics, to open a list of available online help files.
2021 Microchip Technology Inc. and its subsidiaries

Preface
DS50003206A-page 4
•Chapter 2. “Installation”: Contains the information on mounting, power
connection, fuse, voltage, and signal connections.
•Chapter 3. “Operation”: Provides an overview of powering up the product,
understanding the indicator LEDs, adjusting the oscillator frequency, disciplining
to external 1 PPS, and configuring outputs.
•Chapter 4. “Options”: Describes the two optional configurations for
8040C/8040CLN: twelve output and low phase noise.
•Chapter 5. “Technical Support”: Contains information about technical support
for the product, including maintenance, helpful resources, points of contact, and
shipping preparation information.
•Appendix A. “PCN00031”: Process change notification regarding the
8040C/8040CLN internal rubidium reference changing from the SA22C oscillator
to the SA55 oscillator.
•Appendix B. “Revised Information Due to Implementation of SA55”: Expla-
nation of changes to the 8040C/8040CLN start banner, 1 PPS disciplining, and
frequency settings for the change to SA55.
CONVENTIONS USED IN THIS GUIDE
This manual uses the following documentation conventions:
DOCUMENTATION CONVENTIONS
Description Represents Examples
Arial font:
Italic characters Referenced books MPLAB® IDE User’s Guide
Emphasized text ...is the only compiler...
Initial caps A window the Output window
A dialog the Settings dialog
A menu selection select Enable Programmer
Quotes A field name in a window or
dialog
“Save project before build”
Underlined, italic text with
right angle bracket
A menu path File>Save
Bold characters A dialog button Click OK
A tab Click the Power tab
N‘Rnnnn A number in verilog format,
where N is the total number of
digits, R is the radix and n is a
digit.
4‘b0010, 2‘hF1
Text in angle brackets < > A key on the keyboard Press <Enter>, <F1>
Courier New font:
Plain Courier New Sample source code #define START
Filenames autoexec.bat
File paths c:\mcc18\h
Keywords _asm, _endasm, static
Command-line options -Opa+, -Opa-
Bit values 0, 1
Constants 0xFF, ‘A’
Italic Courier New A variable argument file.o, where file can be
any valid filename
Square brackets [ ] Optional arguments mcc18 [options] file
[options]
2021 Microchip Technology Inc. and its subsidiaries

Preface
DS50003206A-page 5
Curly brackets and pipe
character: { | }
Choice of mutually exclusive
arguments; an OR selection
errorlevel {0|1}
Ellipses... Replaces repeated text var_name [,
var_name...]
Represents code supplied by
user
void main (void)
{ ...
}
DOCUMENTATION CONVENTIONS
2021 Microchip Technology Inc. and its subsidiaries

Preface
DS50003206A-page 6
WARNINGS, CAUTIONS, RECOMMENDATIONS, AND NOTES
Warnings, Cautions, Recommendations, and Notes attract attention to essential or crit-
ical information in this guide. The types of information included in each are displayed
in a style consistent with the examples below.
WHERE TO FIND ANSWERS TO PRODUCT AND DOCUMENT QUESTIONS
For additional information about the products described in this guide, please contact
your Microchip representative or your local sales office. You can also contact us on the
web at www.microchip.com/.
When this manual is updated the latest version will be available for downloading from
Microchip’s web site. Manuals are provided in PDF format for ease of use. After down-
loading, you can view the manual on a computer or print it using Adobe Acrobat
Reader.
Manual updates are available at: www.microchip.com/.
THE MICROCHIP WEBSITE
Microchip provides online support via our website at www.microchip.com. This website
is used as a means to make files and information easily available to customers.
Accessible by using your favorite Internet browser, the website contains the following
information:
•Product Support – Data sheets and errata, application notes and sample
programs, design resources, user’s guides and hardware support documents,
latest software releases and archived software
•General Technical Support – Frequently Asked Questions (FAQs), technical
support requests, online discussion groups, Microchip consultant program
member listing
•Business of Microchip – Product selector and ordering guides, latest Microchip
press releases, listing of seminars and events, listings of Microchip sales offices,
distributors and factory representatives
WARNING
To avoid serious personal injury or death, do not disregard warnings. All warnings use
this style. Warnings are installation, operation, or maintenance procedures, practices,
or statements, that if not strictly observed, may result in serious personal injury or even
death.
CAUTION
To avoid personal injury, do not disregard cautions. All cautions use this style. Cau-
tions are installation, operation, or maintenance procedures, practices, conditions, or
statements, that if not strictly observed, may result in damage to, or destruction of, the
equipment. Cautions are also used to indicate a long-term health hazard.
Note: All notes use this style. Notes contain installation, operation, or mainte-
nance procedures, practices, conditions, or statements that alert you to
important information, which may make your task easier or increase your
understanding.
2021 Microchip Technology Inc. and its subsidiaries

Preface
DS50003206A-page 7
CUSTOMER SUPPORT
Users of Microchip products can receive assistance through several channels:
• Distributor or Representative
• Local Sales Office
• Field Application Engineer (FAE)
• Technical Support
Customers should contact their distributor, representative or field application engineer
(FAE) for support. Local sales offices are also available to help customers. A listing of
sales offices and locations is included in the back of this document.
Technical support is available through the website at: www.microsemi.com/ftdsupport
2021 Microchip Technology Inc. and its subsidiaries

Preface
DS50003206A-page 8
DOCUMENT REVISION HISTORY
Revision A (October 2021)
• Initial release of this document as MIcrochip DS50003206A. This Microchip docu-
ment replaces the Microsemi document 15254-201 revision D.
2021 Microchip Technology Inc. and its subsidiaries

8040C/8040CLN USER’S GUIDE
2021 Microchip Technology Inc. and its subsidiaries DS50003206A-page 9
Table of Contents
Preface ........................................................................................................................... 3
Overview ............................................................................................................... 3
Purpose of This Guide........................................................................................... 3
Who Should Read This Guide............................................................................... 3
Document Layout .................................................................................................. 3
Conventions Used in this Guide ............................................................................ 4
Warnings, Cautions, Recommendations, and Notes............................................. 6
Where to Find Answers to Product and Document Questions .............................. 6
The Microchip Website.......................................................................................... 6
Customer Support ................................................................................................. 7
Document Revision History ................................................................................... 8
Chapter 1. Introduction
1.1 Overview ....................................................................................................... 11
1.2 Purpose of Equipment................................................................................... 11
1.3 Factory Configurations .................................................................................. 11
Chapter 2. Installation
2.1 Mounting........................................................................................................ 13
2.2 Power Connection/Fuse/Voltage................................................................... 13
2.3 Signal Connections ....................................................................................... 13
2.3.1 Output Signals............................................................................................ 14
2.3.2 Input Signals............................................................................................... 14
2.3.3 Console ...................................................................................................... 14
Chapter 3. Operation
3.1 Powering Up.................................................................................................. 15
3.2 Indicator LEDs............................................................................................... 15
3.3 Adjusting Oscillator Frequency...................................................................... 15
3.4 Disciplining to External 1 PPS....................................................................... 16
3.4.1 1 PPS Disciplining ...................................................................................... 16
3.4.2 Operation.................................................................................................... 16
3.4.3 Manual Control ........................................................................................... 17
3.4.4 Automatic Control....................................................................................... 17
3.5 Configuring Outputs ...................................................................................... 17
3.6 Console ......................................................................................................... 19
Chapter 4. Options
4.1 Twelve Output Option.................................................................................... 21
4.2 Low Phase Noise Option............................................................................... 21

8040C/8040CLN User’s Guide
DS50003206A-page 10
Chapter 5. Technical Support
5.1 Maintenance.................................................................................................. 23
5.2 Where to Find Answers to Product and Document Questions...................... 23
5.3 Related Documents and Information............................................................. 23
5.4 Customer Support ......................................................................................... 24
5.5 Preparation for Shipment .............................................................................. 24
Appendix A: PCN-00031...............................................................................................25
Appendix B: Revised Information Due to the Implementation of SA55
B.1 Start Banner.................................................................................................. 27
B.2 Revision to 1 PPS Disciplining Section Based on SA55 Functionality.......... 28
B.3 Revision to Frequency Settings Section Based on SA55 Functionality........ 29
Worldwide Sales and Service......................................................................................31
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8040C/8040CLN USER’S GUIDE
2021 Microchip Technology Inc. and its subsidiaries DS50003206A-page 11
Chapter 1. Introduction
1.1 OVERVIEW
This manual contains procedures and information for proper installation and operation
of the Microchip 8040C/8040CLN Rubidium Frequency Standard.
1.2 PURPOSE OF EQUIPMENT
The 8040C/8040CLN is a highly accurate and stable Rubidium frequency reference
standard that provides atomic clock performance in a user-configurable 1U rack-mount
chassis. Each of the connectors can be individually programmed to generate any of the
following frequency outputs:
• 1 MHz, 5 MHz, or 10 MHz sine wave
• 1 MHz, 5 MHz, or 10 MHz square wave
• 1 PPS
The 8040C uses Microchip’s model SA22C Rubidium as its internal oscillator, and
provides direct user control via an RS-232 to perform the following tasks:
• Adjust the SA22C Rubidium oscillator frequency.
• Tune the SA22C to an external 1 PPS input.
1.3 FACTORY CONFIGURATIONS
Note: Please refer to Appendix 9. “PCN00031” and Appendix 10. “Revised
Information Due to Implementation of SA55” for models incorporating
the SA55.
TABLE 1-1: FACTORY CONFIGURATIONS
Part Number Description
15230-101 Six Outputs, Standard Performance
15230-102 Twelve Outputs, Standard Performance
15230-104 Six Outputs, Low Phase Noise
15230-105 Twelve Outputs, Low Phase Noise
15230-106 Twelve Outputs (all 10 MHz sine), Standard Performance
15230-111 Twelve Outputs (all 10 MHz sine), Low Phase Noise, DC Power

8040C/8040CLN User’s Guide
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NOTES:
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8040C/8040CLN USER’S GUIDE
2021 Microchip Technology Inc. and its subsidiaries DS50003206A-page 13
Chapter 2. Installation
2.1 MOUNTING
The Microchip 8040C mounts in standard 19-inch equipment racks and takes up 1U of
vertical space (1.75 inches). The chassis depth is 12 inches.
For best performance, the operating environment should have a stable temperature.
In addition, ensure that there are no strong magnetic fields (>2 gauss) in the vicinity of
the shelf, because the unit’s Rubidium oscillator is sensitive to DC and AC magnetic
fields.
2.2 POWER CONNECTION/FUSE/VOLTAGE
The Microchip 8040C is powered from an AC source or optionally from a 24V DC
source. The AC fuse is located inside the AC connector/filter on the rear panel.
To change the fuse, open the cover on the rear panel AC connector by using a screw-
driver on the connector’s cover slot. Once the cover is open, the fuse holder may be
removed for inspection or replacement.
The Microchip 8040C/8040CLN may be powered from 90V AC or 240V AC. The 8040C
automatically detects the input voltage therefore no manual configuration is required.
Microchip does not provide a power cable for the 24V DC version of the product. An 18
AWG cable is suggested with Molex connector 0003121026 and crimp terminal Molex
0018121222.
2.3 SIGNAL CONNECTIONS
Output signal cables may be connected in any order to the rear panel BNC connectors.
FIGURE 2-1: 8040C/8040CLN Standard Configuration – Rear Panel AC
version.
DANGER
ELECTRICAL SHOCK HAZARD - Use a locally approved power cord or power cord
adapter for connection to the power source.

8040C/8040CLN User’s Guide
DS50003206A-page 14
FIGURE 2-2: 8040C/8040CLN Standard Configuration – Rear Panel DC
version.
2.3.1 Output Signals
The standard Microchip 8040C/8040CLN has six BNC output connectors. The outputs
are factory-programmed as described in Table 5-1.
2.3.2 Input Signals
The 1 PPS IN connector takes a 1 PPS input from an external source, such as a GPS
receiver or Cesium frequency standard, which is then used to discipline the 8040C’s
Rubidium oscillator. See Section 6.4 “Disciplining to External 1 PPS”.
2.3.3 Console
The RS-232 connector on the 8040C/8040CLN’s back panel provides a command line
interface to perform the following tasks:
• Adjust the Rubidium oscillator’s frequency
• Synchronize to an external 1 PPS input
TABLE 2-1: FACTORY SETTINGS FOR STANDARD OUTPUTS
BNC # Signal
1 10 MHz sine wave
2 10 MHz sine wave
3 10 MHz sine wave
4 5 MHz sine wave
5 1 MHz sine wave
6 1 PPS
7-12 Optional (not included in the base configuration)
TABLE 2-2: RS-232 CONNECTOR PIN-OUT
DB9-F Function
3 TX (Transmit Data)
2 RX (Receive Data)
5 GND (Signal Ground)
Note: Requires a null modem cable (DTE).
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8040C/8040CLN USER’S GUIDE
2021 Microchip Technology Inc. and its subsidiaries DS50003206A-page 15
Chapter 3. Operation
3.1 POWERING UP
Connecting the power cord from the 8040C/8040CLN to the AC or DC source provides
power to the unit. For the DC version, on the power cord apply:
• 24V DC on the red wire
• Ground or return on the black wire
The POWER LED illuminates immediately thereafter. The LOCK LED illuminates within
five minutes, indicating that the 8040C’s frequency accuracy is within ±5E-8 of absolute
frequency. Removing the power cord from the IEC receptacle on the rear panel turns
the power off.
3.2 INDICATOR LEDS
The three LED indicators on the front panel provide a cursory view of the
8040C/8040CLN operating status.
POWER is lit when AC or DC power is applied to the unit.
LOCK is lit when the unit’s Rubidium oscillator reaches operating temperature and its
frequency output is within specifications.
1 PPS SYNC is lit when a valid external 1 PPS signal is applied to 1 PPS IN.
FIGURE 3-1: Microchip 8040C/8040CLN Front Panel.
3.3 ADJUSTING OSCILLATOR FREQUENCY
There are two reasons to adjust the unit’s frequency output:
• To adjust for the effects of aging on the Rubidium oscillator’s frequency
• To tune the Rubidium oscillator’s frequency to that of a more accurate primary fre-
quency source.
The Microchip 8040C/8040CLN is a secondary frequency standard (i.e., much more
accurate than a quartz frequency standard, but not as accurate as a Cesium primary
frequency standard). By comparing the Microchip 8040C/8040CLN to an external
Cesium standard or GPS receiver, it can be readjusted periodically to match the
primary standard’s greater accuracy.
CAUTION
Do not use the Microchip 8040C as a reference source until the LOCK indicator is
turned on.

8040C/8040CLN User’s Guide
DS50003206A-page 16
The 8040C/8040CLN output frequency is adjusted by using the RS-232 interface.
The f command allows the user to adjust the output frequency in parts <1E-11.
Example:
1. At the r> prompt, enter f
- For a 5E-11 change, enter f5<CR>
- For a –5E-11 change, enter f–5<CR>
2. Press ENTER
3. At the r> prompt, enter t
4. Under the t, enter 5987717 (this is the pass code save command)
5. Press ENTER (unless changes are saved they will not be recorded)
6. Response: “Tuning Data Save”
3.4 DISCIPLINING TO EXTERNAL 1 PPS
3.4.1 1 PPS Disciplining
The advent of low-cost GPS technology has brought about its widespread use through-
out the telecommunications industry. The GPS system provides 1 PPS with extremely
good long-term stability (e.g., <1E-12 averaged over 24 hours). However, the
short-term stability of this signal is not suitable due to inherent noise perturbations in
GPS related to background noise, atmospheric conditions, cross talk, multipath, and
instabilities in the oscillators of GPS satellites and GPS receivers.
In order to provide the required stability for telecommunications, system designers
must combine the benefits of short-term stability (such as from a Rubidium or low noise
OCXO) with long-term stability (such as from GPS, Loran-C, GLONASS, or Cesium).
In the past, external disciplining circuitry was required to combine short-term and
long-term stability. The traditional approach involved adding an external circuit to the
oscillator that had a phase lock loop detector to handle disciplining algorithms.
Microchip is a leader in time and frequency design and has pioneered the use of
Rubidium oscillators in telecommunications. The model SA22C Rubidium oscillator in
the Microchip 8040C/8040CLN provides an important new feature: built-in disciplining
to a 1 PPS input from an external reference. This new feature eliminates the need for
additional external disciplining circuitry. The 8040C/8040CLN is inherently capable of
disciplining to an external primary reference to remove frequency offsets due to
long-term aging.
3.4.2 Operation
Connect the 1 PPS source to the 1 PPS IN on the rear panel of the 8040C/8040CLN.
The 8040C/8040CLN’s Microchip Synchronization Adaptive Algorithm (SSAA) quali-
fies the 1 PPS input reference by detecting 256 valid 1 PPS input pulses and determin-
Note: A typical external counter does not have a resolution or accuracy high
enough to set this device, so do not reset the frequency unless established
metrology methods are used for frequency measurement resolution of
<1E-11.
Note: Please refer to Appendix 10. “Revised Information Due to Implementa-
tion of SA55” for revisions that incorporated the SA55.
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Operation
2021 Microchip Technology Inc. and its subsidiaries DS50003206A-page 17
ing the number of outliers based on the time constant. An outlier is detected when the
absolute time difference between the input 1 PPS and its expected time is greater than
1 microsecond.
Once the SSAA detects two outliers (two bad 1 PPS pulses) or no input 1 PPS, the
algorithm places the 8040C/8040CLN into flywheel (holdover) mode. The flywheel
mode provides for Rubidium short-term and long-term stability without the benefit of an
external reference. The 8040C/8040CLN remains in flywheel mode until 256 “good”
1 PPS input pulses are detected.
Once the number of outliers is less than 2, the unit disciplines to the external reference.
This implementation was designed to support applications where the reference input is
a GPS receiver without serial communications between the receiver and the
8040C/8040CLN.
There are two modes of operation for the 1 PPS input: manual and automatic.
3.4.3 Manual Control
The manual mode is beneficial to applications where the quality of 1 PPS is worse than
50 nanoseconds, or to applications where the noise profile is well known and a
deterministic solution yielding more control to the system designer is desired. The
manual mode requires the user to input two parameters, which are tau (or time con-
stant) and dampening factor.
Tau is expressed in seconds and determines the PLL time constant for following a step
in phase for the reference. The range of tau is 5 seconds to 100,000 seconds. Tau val-
ues outside of this range put the unit in automatic disciplining mode.
The dampening factor determines the relative response time and ringing in response
to each step. There are no limitations for the dampening factor value; however, values
between 0.5 and 2 are strongly recommended.
3.4.4 Automatic Control
The automatic mode requires no user inputs to the SA22C Rubidium oscillator.
Automatic mode is adaptive and changes the SSAA time constant as changes in the
1 PPS reference are detected. The automatic mode is optimized for a 1 PPS input with
up to 50 nanoseconds RMS of noise such as from a GPS timing receiver.
Because the short-term jitter of 50 nanoseconds is typically present on 1 PPS from a
GPS reference, the automatic mode is generally suitable for most applications.
3.5 CONFIGURING OUTPUTS
The 8040C/8040CLN has the unique capability of providing flexible output configura-
tions. To change the output configuration of your 8040C/8040CLN:
1. Unplug the 8040C/8040CLN from the AC or DC power source and remove the
Note: Please refer to Appendix 10. “Revised Information Due to Implementa-
tion of SA55” for revisions that incorporated the SA55.
Note: Please refer to Appendix 10. “Revised Information Due to Implementa-
tion of SA55” for revisions that incorporated the SA55.
Note: Please refer to Appendix 10. “Revised Information Due to Implementa-
tion of SA55” for revisions that incorporated the SA55.

8040C/8040CLN User’s Guide
DS50003206A-page 18
top cover by removing the Phillips head screws around the perimeter of the unit.
2. Locate the main PCB inside the 8040C/8040CLN as indicated in the top half of
Figure 6-2 and identify the dipswitches shown in the bottom half of Figure 6-2.
Each dipswitch configures the output format on its corresponding BNC (e.g.,
SW1 configures the output format on BNC1).
FIGURE 3-2: Dipswitch Locations for Configuring Outputs.
3. Use the dipswitch positions shown in Table 6-1 to generate a specific output for-
mat on a specific BNC. For example, to generate 10 MHz TTL on BNC3, set SW3
position 1 to ON, position 2 to OFF, and position 3 to OFF.
2021 Microchip Technology Inc. and its subsidiaries

Operation
2021 Microchip Technology Inc. and its subsidiaries DS50003206A-page 19
4. After setting the outputs, replace the top cover and apply power.
3.6 CONSOLE
The Microchip Serial Interface Protocol (SIP) provides user communication with the
8040C/8040CLN through the serial port when the unit is connected to a host PC or
terminal. All “developer-mode” commands are single-letter format.
3.6.1 Host Terminal Emulator Setup
Set up the comm port of the PC with the following configuration:
• Data rate (Baud/BPS - see note below)
• No parity
• 8 data bits
• 1 stop bit
• No local echo (unit echoes)
• No hardware or software flow control
All SSIP commands are a single ASCII letter. The baud rate of the 8040C/8040CLN is
57.6K.
TABLE 3-1: OUTPUT CONFIGURATION
Output Format Position 1 Position 2 Position 3
10 MHz sine OFF OFF OFF
10 MHz TTL ON OFF OFF
5 MHz sine OFF OFF ON
5 MHz TTL ON OFF ON
1 MHz sine OFF ON OFF
1 MHz TTL ON ON OFF
1 PPS ON ON ON
Note: Requires a null modem cable (DTE).

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DS50003206A-page 20
NOTES:
2021 Microchip Technology Inc. and its subsidiaries