SM3-IT-077.76MHZ [CONNOR-WINFIELD]
Telecom IC, MDIP28;型号: | SM3-IT-077.76MHZ |
厂家: | CONNOR-WINFIELD CORPORATION |
描述: | Telecom IC, MDIP28 |
文件: | 总32页 (文件大小:327K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
SM3-IT
ULTRA MINIATURE
STRATUM 3 MODULE
2111 Comprehensive Drive
Aurora, Illinois 60505
Phone: 630-851-4722
Fax: 630-851-5040
www.conwin.com
Application
Features
• Industrial Temp. Range (-40
The SM3-IT Timing Module is a
complete system clock module for
Stratum 3 timing applications and
conforms to GR-1244-CORE
(Issue 2), GR-253-CORE (Issue
3), ITU-T G.812 (Type 3) and ITU-
T G813 (Option 2). Applications
include shared port adapters, data
digital cross connects, ADM's,
DSLAM's, multiservice platforms,
switches and routers in TDM,
SDH and SONET environments.
The SM3-IT Timing Module
to 85°C)
• Small Package Size, 1.45 x
1.0 x 0.515 inches
• Four Auto Select Input
References, 8 kHz - 77.76
MHz
• Frequency Qualification and
Loss of Reference detection
for each input
• Master/Slave Operation with
Phase Adjustment
• Manual/Autonomous
Operation
helps reduce the cost of your
design by minimizing your
• Bi-Directional SPI Port
Control
development time and maximizing
your control of the system clock
with our simplified design.
• Three CMOS Frequency
Outputs - Output1 from
12.96 - 77.76 MHz, M/S
Output @ 8kHz, BITS
Bulletin
TM064
Page
1 of 32
Revision
01
@2.048 MHz or 1.544 MHz
Date
15 OCT 07
• 3.3V operation
Issued By
MBatts
General Description
The SM3-IT timing module provides a clock output that meets or exceeds Stratum 3 specifications given in GR-1244-CORE (Is-
sue 2), GR-253-CORE (Issue 3), ITU-T G.812 (Type 3) and ITU-T G813 (Option 2). The SM3-IT features four reference inputs that
will auto-detect the following reference frequencies: 8 kHz, 1.544 MHz, 2.048 MHz, 12.96 MHz, 19.44 MHz, 25.92 MHz, 38.88 MHz,
51.84 MHz and 77.76 MHz.
The SM3-IT timing module can be configured during production to produce an output up to 77.76 MHz.This output is derived
from an onboard VCXO and must be specified when ordering. The BITS output selectable for either 1.544 or 2.048 MHz. The mas-
ter/slave output is 8KHz. The user communicates with the SM3-IT module through a SPI port.The user controls the SM3-IT opera-
tion by writing to the appropriate registers. The user can also enable or disable SPI operation through a SPI_Enable pin.
The SM3-IT offers a wide range of options for the system designer. The bandwidth is SPI Port-selectable from 0.025 Hz to 1.6
Hz. 0.098 Hz is the recommended operational bandwidth for SONET Minimum Clock and most Stratum 3 applications. The 8 kHz
output has an adjustable pulse width. The pull-in range is also adjustable to establish the desired reference frequency rejection
limits. A Free Run frequency calibration value can be written to the module to provide a high degree of accuracy in the free run
mode. The reference frequency for any given reference input is automatically detected. A wealth of status information is available
through the SPI Port registers. The user also has a choice between autonomous or full manual control operation.
In manual mode, the user controls the module operating modes Free Run, Hold Over or locked to a specific reference in normal
mode. If the chosen reference is unavailable or disqualified the module automatically enters Hold Over.
In autonomous control mode, operational mode selection occurs automatically based on reference priority and qualification sta-
tus. When the active reference becomes disqualified, the module will switch to another qualified reference. If none is available, it will
switch to Holdover. In the revertive mode the module will seek to acquire the highest priority qualified reference. In the non-revertive
mode the module will not return to the previous reference even after it is re-qualified unless there are no other qualified references.
Switching between references is hitless. Likewise, the output frequency slew rate is minimized during any change of operating
mode, including entry into and return from Free Run or Hold Over to protect traffic from transient-induced bit errors.
Reference Status information and the operating mode information is accessed through status registers. The module will set the
Interrupt pin (SPI_INT) low to indicate a status change. An Alarm pin is used to indicate failure of the active reference status.
Free Run operation guarantees an output within 4.6ppm of nominal frequency and Holdover operation guarantees the output
frequency will not change by more than 0.37ppm during the first 24 hours. Frequency accuracy is based on a TCXO for its small
size, low power consumption and outstanding performance over all environmental conditions.
The module operates on 3.3V ± 5% with a typical power drain of less than 1.6W at turn on, dropping to approximately 1W @
room temperature after warming up. The module operates over the -40° to 85° C industrial temperature range.
Functional Block Diagram
Figure 1
TRST
TCK
TDO
TDI
EEPROM
DAC
OCXO
VCXO
OUTPUT1
M/S_OUT
BITS_CLK
TMS
Reference Input Monitor
M/S REF
REF 1 - 4
RESET
4
Control
Mode
Reference
Selection
DPLL
APLL
MASTER SELECT
T1/E1
LOS
Reference Priority,
Revertivity and Mask
Table
LOL
SPI_ENBL
SPI_CLK
SPI_IN
HOLD_GOOD
SPI_OUT
SPI_INT
Bus Interface
Data Sheet #: TM064 Page 2 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Specifications for Ultra Miniature Stratum 3 - Industrial Temperature
Table 1
Parameter
Voltage
Specification
3.3V ± 5%
Power
1.6W Maximum during start up, 1.0W Typical @ room temperature
Operating Temp Range
-40° - 85°C
Reference Frequency 1, 2, 3, 4
8 kHz - 77.76 MHz (Auto Detected)
CMOS Output Frequency #1
M/S Output
BITS_Clk
12.96 MHz - 77.76 MHz
8 kHz
1.544/2.048 MHz (Selectable)
Master/Slave Input Reference
Free Run Accuracy
Hold Over Stability
Dimensions
8 kHz - 77.76 MHz
4.6 ppm
0.37 ppm
1.45 x 1.0 x 0.515 inches (36.83 x 25.4 x 13.08 mm)
Pin Description
Table 2
Pin #
1
I/O
Pin Name
LOS
Pin Description
Alarm output - Loss of Active Reference Signal
Alarm Output - Loss of Lock
Master/Slave reference input – 8 kHz to 77.76 MHz auto detected
Reference Input 1 – 8 kHz to 77.76 MHz auto detected
Reference Input 2 – 8 kHz to 77.76 MHz auto detected
Reference Input 3 – 8 kHz to 77.76 MHz auto detected
Reference Input 4 – 8 kHz to 77.76 MHz auto detected
JTAG TDI pin*
O
O
I
2
3
LOL
M/S REF
REF1
4
5
I
I
REF2
6
I
REF3
7
8
I
REF4
TDI
9
TMS
JTAG TMS pin*
10
11
12
13
TRST
JTAG TRST pin*
O
O
O
BITS_CLK
M/S_OUT
OUTPUT1
1.544 or 2.048 MHz output selected by pin 16
Master/Slave 8 kHz output
Synchronous Primary Output
Positive Programming Supply Pin. During normal operation it is
recommended to float this pin.
Negative Programming Supply Pin. During normal operation it is
recommended to float this pin.
14
15
I
I
VPP
VPN
16
17
18
19
20
21
22
23
I
T1/E1
HOLD_GOOD
TDO
BITS_CLK select input – 1=1.544 MHz, 0=2.048 MHz
Holdover Good Output Flag – 1=Holdover Available
JTAG TDO pin*
O
TCK
GND
JTAG TCK pin*
Module Ground
I
I
SPI_CLK
SPI_IN
VCC
SPI Port Clock input
SPI Port Data input
3.3 Vdc VCC Supply Input
24
I
SPI_ENBL
SPI Port Enable input – Active Low
25
26
I
O
RESET
SPI_OUT
Module Reset – Active Low, 10 ms Hold time
SPI Port Data Output
27
28
O
I
SPI_INT
SPI Port Interrupt Output – Active Low
MASTER SELECT Master/Slave select input – 1=Master, 0=Slave
Data Sheet #: TM064 Page 3 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Pin Diagram
Figure 2
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
LOS
LOL
MASTER SELECT
SPI_INT
SPI_OUT
RESET
SM3G5
2
3
M/S REF
REF1
4
5
REF2
SPI_ENBL
Vcc
6
REF3
7
REF4
SPI_IN
(TOP VIEW)
8
TDI
SPI_CLK
GND
9
TMS
10
11
12
13
14
TRST
TCK
BITS_CLK
M/S_OUT
OUTPUT1
VPP
TDO
HOLD_GOOD
T1/E1
VPN
Register Map
Table 3
Address
Reg Name
Description
Type
R
0x00
Chip_ID_Low
Low byte of chip ID
High byte of chip ID
0x01
Chip_ID_High
Chip_Revision
Bandwidth
R
0x02
Chip revision number
Bandwidth Select
R
0x03
R/W
R/W
0x04
Ctl_Mode
Manual or automatic selection of Op_Mode,BITS clock output frequency
indication, and frame/multi-frame sync pulse width mode control
0x05
0x06
0x07
0x08
0x09
0x0a
0x0b
0x0c
Op_Mode
Master Free Run, Locked, or Hold Over mode, or Slave mode
Maximum pull-in range in 0.1 ppm units
Cross Reference activity
R/W
R/W
R
Max_Pullin_Range
M/S REF_Activity
Ref_Activity
Activities of 4 reference inputs
R
Ref_Pullin_Sts
Ref_Qualified
Ref_Mask
In or out of pull-in range of 4 reference inputs
Qualification status of 4 reference inputs
Availability mask for 4 reference inputs
Availability of 4 reference inputs
R
R
R/W
R
Ref_Available
Data Sheet #: TM064 Page 4 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Map Continued
0x0d
0x0e
Ref_Rev_Delay
Phase_Offset
Reference reversion delay time, 0 - 255 minutes
R/W
Phase offset between M/S REF & M/S Output (for the Slave in M/S operation)
in 250ps resolution
R/W
R/W
R/W
R
0x0f
Calibration
Local oscillator digital calibration in 0.05 ppm resolution
Frame sync pulse width
0x10
0x11
0x12
0x13
0x14
0x15
0x16
0x17
0x18
0x19
0x1a
0x1b
0x1c
0x1d
0x1e
0x1f
Fr_Pulse_Width
DPLL_Status
Intr_Event
Digital Phase Locked Loop status
Interrupt events
R
Intr_Enable
Enable individual interrupt events
R/W
R
Ref1_Frq_Offset1
Ref2_Frq_Offset2
Ref3_Frq_Offset3
Ref4_Frq_Offset4
Reserved
Ref1 frequency offset in 0.2 ppm resolution
Ref2 frequency offset in 0.2 ppm resolution
Ref3 frequency offset in 0.2 ppm resolution
Ref4 frequency offset in 0.2 ppm resolution
R
R
R
Reserved
Reserved
Reserved
Ref1_Frq_Priority1
Ref2_Frq_Priority2
Ref3_Frq_Priority3
Ref4_Frq_Priority4
Reserved
Ref1 frequency and priority
Ref2 frequency and priority
Ref3 frequency and priority
Ref4 frequency and priority
R/W
R/W
R/W
R/W
0x20
0x21
0x22
0x23
0x24
0x25
0x26
0x27
0x30
0x31
0x32
0x33
0x36
0x37
0x38
0x39
Reserved
Reserved
Reserved
FreeRun Priority
History_Policy
History_CMD
HoldOver_Time
Cfgdata
Control and Priority for designation of Free Run as a reference
Sets policy for Hold Over history accumulation
Save, restore and flush comands for Hold Over history
Indicates the time since entering Hold Over state
Configuration data write register
R/W
R/W
R/W
R
R/W
R
Cfgctr_Lo
Configuration data write counter, low byte
Cfgctr_Hi
Configuration data write counter, high byte
R
Chksum
Configuration data checksum pass/fail indicator
Disables/Enables writing to the external EEPROM
R
EE_Wrt_Mode
EE_Cmd
R/W
Read/Write command & ready indication register for ext. EEPROM access R/W
EE_Page_Num
EE_FIFO_Port
Page number for external EEPROM access
Read/Write data for external EEPROM access
R/W
R/W
Data Sheet #: TM064 Page 5 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Detailed Description
The SM3-IT can accept up to 4 external references from 8 kHz to 77.76 MHz and each is monitored for signal presence and
frequency offset. Additionally, a cross-couple reference input is provided for master/slave operation. Reference selection may be manual
or automatic, according to pre-programmed priorities. All reference switches are performed in a hitless manner, and frequency ramp
controls ensure smooth output signal transitions. When references are switched, the device provides an automatic phase build-out to
minimize phase transitions in the output clocks.
Three output signals are provided, the first up to 77.76 MHz , the second fixed at 8 kHz for use as a Frame Sync signal as well as a
cross-couple reference for master/slave operation. In slave mode, the output phase may be adjusted from -32 to +31.75nS relative to the
master, to accommodate downstream system needs, such as different clock distribution path lengths.The third output is a BITS clock,
selectable as either 1.544 MHz or 2.048 MHz.
Device operation may be in Free Run, locked, or Hold Over modes.In Free Run, the clock frequencies are simply determined by the
accuracy of the calibrated internal clock. In locked mode, the SM3-IT phase locks to the selected input reference. While locked, a
frequency history is accumulated. In Hold Over mode, the output frequencies are generated according to this history.
The Digital Phase Locked Loop provides the critical filtering and frequency/phase control that meet or exceed all requirements in
critical jitter and accuracy performance parameters. Filter bandwidth may be configured to suit applications requirements.
Control functions are provided via standard SPI bus register interface. Register access provides visibility into a variety of registered
information as well as providing extensive programmable control capability.
Operating Modes:The SM3-IT Operates in Either Free Run, Locked, or Hold Over Mode:
Free Run – In Free Run mode, Output 1, M/S Output, and BITS_Clk, the output clocks, are determined directly from and have the
accuracy of the calibrated free running internal clock. Reference inputs continue to be monitored for signal presence and frequency
offset, but are not used to synchronize the outputs.
Locked – The Output 1, M/S Output, and BITS_Clk, outputs are phase locked and track the selected input reference. Upon entering
the Locked mode, the device begins an acquisition process that includes reference qualification and frequency slew rate limiting, if
needed. Once satisfactory lock is achieved, the “Locked” bit is set in the DPLL_Status register, and a compilation of the frequency history
of the selected reference is started. When a usable Hold Over history has been established, the Hold_Good pin is set, and the “Hold
Over Available” bit is set in the DPLL_Status register.
Phase comparison and phase lock loop filtering operations in the SM3-IT are completely digital. As a result, device and loop behavior
are entirely predictable, repeatable, and extremely accurate.Carefully designed and proven algorithms and techniques ensure completely
hit-less reference switches, operational mode changes, and master/slave switches.
Basic loop bandwidth is programmable from .025 Hz to 1.6 Hz, giving the user a wide range of control over the system response.
When a new reference is acquired, maximum frequency slew limits ensure smooth frequency changes. Once lock is achieved, (<100
seconds for stratum 3), the “Locked” bit is set. If the SM3-IT is unable to maintain lock, Loss of Lock (LOL) is asserted. All transitions
between locked, Hold Over and Free Run modes are performed with minimal phase events and smooth frequency and phase transitions.
Reference phase hits or phase differences encountered when switching references (or when entering locked mode) are nulled out
with an automatic phase build-out function, with a residual phase error of less than 1ns.
Hold Over – Upon entering Hold Over mode, the Output 1, M/S Output, and BITS_Clk, outputs are determined from the Hold Over
history established for the last selected reference. Output frequency is determined by a weighted average of the Hold Over history, and
accuracy is determined by the internal clock. Hold Over mode may be entered manually or automatically. Automatic entry into Hold Over
mode occurs when operating in the automatic mode, the reference is lost, and no other valid reference exists. The transfer into and out of
Hold Over mode is designed to be smooth and free of hits.The frequency slew is also limited to a maximum of ±2 ppm/sec.
The history accumulation algorithm uses a first order frequency difference filtering algorithm. Typical holdover accumulation takes
about 15 minutes. When a usable holdover history has been established, the Hold_Good pin is set, and the “Holdover Available” bit is set
in the DPLL_Status register. The holdover history continues to be updated after “Holdover Avaialble” is declared.
The algorithm accumulates the holdover history only when it has locked to either an external reference in Master operation or the M/S
REF clock in Slave operation, starting 15 minutes after power up. Tracking will be suspended automatically when switching to a new
reference and in Hold Over or Free Run mode. A set of registers allows the application to control a holdover history maintenance policy,
enabling either a re-build or continuance of the history when a reference switch occurs.
Data Sheet #: TM064 Page 6 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Detailed Description continued
Furthermore, under register access control, a backup holdover history register is provided. It may be loaded from the active holdover
history or restored to the active holdover history. The active holdover history may also be flushed.
Holdover mode may be entered at any time. If there is no holdover history available, the prior output frequency will be maintained.
When in holdover, the application may read (via register access) the time since holdover was enterred.
Master/Slave Operation
Pairs of SM3-IT devices may be operated in a master/slave configuration for redundant timing source applications. A typical
configuration is shown below.:
Master / Slave Configuration
Figure 3
REFS1-4
SM3
M/S OUTPUT / OUTPUT1
1
M/S REF
M/S REF
SM3
2
M/S OUTPUT / OUTPUT1
REFS1-4
The M/S Output or the Output 1 of each device may be cross-connected to the other device’s M/S Ref input.The device auto-detects
the frequency on the M/S Ref input. Master or slave state of a device is determined by the M/S pin.Thus, master/slave state is always
manually controlled by the application.The master synchronizes to the selected input reference, while the slave synchronizes to the M/S
Ref input. (Note that 8kHz frame phase alignment is maintained across a master/slave pair of devices only if M/S Output is used as the
cross couple signal.)
The unit operating in slave mode locks on and phase-aligns to the cross-reference clock (M/S Output or Output 1) from the unit in
master mode. The phase skew between the input cross-reference and the output clock for the slave unit is typically less than ±1ns (under
±3ns in dynamic situations, including reference jitter and wander).
Perfect phase alignment of the two Output 1 output clocks would require no delay on the cross-reference clock connection.To
accommodate path length delays, the SM3-IT provides a programmable phase skew feature.The slave’s Output 1 or M/S Output may be
phase shifted -32nS to +31.75nS relative to M/S Input according to the contents of the MS_Phase_Offset register to compensate for the
path length of the M/S Output or Output 1 to M/S Input connection.This offset may therefore be programmed to exactly compensate for
the actual path length delay associated with the particular application's cross-reference traces. The offset may further be adjusted to
accommodate any output clock distribution path delay differences. Thus, master/slave switches with the SM3-IT devices may be
accomplished with near-zero phase hits.
The first time a unit becomes a slave, such as immediately after power-up, its output clock phase starts out arbitrary, and will quickly
phase-align to the cross-reference from the master unit. The phase skew will be eliminated (or converged to the programmed phase
offset) step by step. The whole pull-in-and-lock process will complete in about 60 seconds. There is no frequency slew protection in slave
mode. In slave mode, the unit's mission is to lock to and follow the master.
Once a pair of units has been operating in aligned master/slave mode, and a master/slave switch occurs, the unit that becomes
master will maintain its output clock phase and frequency while a phase build-out (to the current output clock phase) is performed on its
selected reference input.Therefore, as master mode operation commences, there will be no phase or frequency hits on the clock output.
Likewise, the unit that becomes the slave will maintain its output clock frequency and phase for 1 msec before starting to follow the
cross-reference, protecting the downstream clock users during the switch. Assuming the phase offset is programmed for the actual
propagation delay of this cross-reference path, there will again be no phase hits on the output clock of the unit that has transitioned from
master to slave.
Data Sheet #: TM064 Page 7 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Detailed Description continued
Serial Communication
The user can control the operation of the SM3-IT module through the SPI port. Timing diagrams are shown below. This interface is
only for point-to-point applications.
Serial Interface Timing, Read Access
Figure 4
SPI_ENABLE
tCS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
SPI_CLK
tCH
tCL
tRWs
tRWh
A0
A1
A2
A3
A4
A5
A6
0
SPI_IN
MSB
LSB
tDRDY
SPI_OUT
D0
D1
D2
D3
D4
D5
D6
D7
LSB
MSB
NOTE: SPI_OUT is normally held at logic 0 except when tri-stated during an
address read cycle on the SPI_IN pin or when data is being output on the
SPI_OUT pin.
Serial Interface Timing, Write Access
Figure 5
SPI_ENABLE
SPI_CLK
tCS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
tCH
tCL
tRWs
tRWh
SPI_IN
A0
A1
A2
A3
A4
A5
A6
1
D0
D1
D2
D3
D4
D5
D6
D7
MSB
MSB
LSB
LSB
SPI_OUT
Data Sheet #: TM064 Page 8 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Detailed Description continued
Serial Interface Timing
Table 4
Symbol
tCS
Parameter
Minimum
Nominal
Maximum
Units
ns
Notes
SPI_Enable low to SPI_CLK low
SPI_CLK high time
SPI_CLK low time
Read/Write setup time
Read/Write hold time
Data ready
15
25
25
15
15
-
-
-
-
-
-
-
-
-
-
-
-
tCH
ns
tCL
-
ns
tRWs
tRWh
tDRDY
tHLD
-
ns
-
ns
25
-
ns
Data Hold
15
5
ns
tCSTRI
tCSMIN
Chip Select to data tri-state
-
ns
Minimum delay between successive accesses 300
-
ns
Reference Input Quality Monitoring
Each reference input is monitored for signal presence and frequency offset. Signal presence for the Ref1-4 inputs is indicated in the
Ref_Activity register and signal presence for the M/S REF is indicated in bit 0 of the M/S REF_Activity register. The frequency offset
between the Ref1-4 inputs and the calibrated local oscillator is available in the Ref_Frq_Offset registers (4). Register Ref_Pullin_Sts
indicates, for each of the Ref1-4 inputs, if the reference is within the maximum pull-in range. The maximum pull-in range is indicated in
register Max_Pullin_Range, and may be set in 0.1ppm increments. Typically, it would be set according to the values specified by the
standards (GR-1244) appropriate for the particular stratum of operation.
The Ref_Qualified register contains the “anded” condition of the Ref_Activity and Ref_Pullin_Sts registers for each of the Ref1-4
inputs, qualified for 10 seconds. When a reference signal has been present for > 10 seconds and is within the pull-in range, it’s bit is set.
The Ref_Available register contains the “anded” condition of the Ref_Qualified register and the Ref_Mask register, and therefore
represents the availability of a reference for selection when automatic reference and operational mode selection is enabled.
Reference Input Selection, Frequencies, and Mode Selection
One of four reference input signals (Ref 1-4) are selected for synchronization in Master mode (as below in the Op_Mode register
description. 0x05). Ref1-4 may each be 8 kHz, 1.544 MHz, 2.048 MHz, 12.96 MHz, 19.44 MHz, 25.92 MHz, 38.88 MHz, 51.84 MHz or
77.76 MHz.
Reference frequencies are auto-detected (frequency determined by the chip) and the detected frequency can be read from the
Ref_Frq_Priority registers (See Register Descriptions and Operation section).
Active reference and operational mode selection may be manual or automatic, as determined by bit 1 in the Ctl_Mode register. In
manual mode, register writes to Op_Mode select the reference and mode.
The M/S REF input for slave operation is frequency auto-detected and may be 8kHz, 1.544MHz, 2.048MHz, 12.96MHz, 19.44MHz,
25.92MHz, 38.88MHz, 51.84MHz or 77.76MHz. Signal presence and frequency for the M/S REF input is indicated in bits 0-3 of the M/S
REF_Activity register.
Active reference and operational mode selection may be manual or automatic, as determined by bit 1 in the Ctl_Mode register. In
manual mode, register writes to Op_Mode select the reference and mode. The reset default is manual mode.
In automatic mode, the reference is selected according to the priorities written to the four Ref_Frq_Priority registers. Individual
references may be masked for use/non-use according to the Ref_Mask register.A reference may only be selected if it is “available” - that
is, it is qualified, as indicated in the Ref_Qualified register, and is not masked (See Reference Input Quality Monitoring and Register
Descriptions and Operation sections).
Furthermore, Bit 3 of each Ref_Frq_Priority register will determine if that reference is revertive or non-revertive. When a reference
fails, the next highest priority “available” (signal present, non-masked, and acceptable frequency offset) reference will be selected.When
a reference returns, it will be switched to only if it is of higher priority and the current active reference is marked “Revertive”. Additionally,
the reversion is delayed according to the value written to the Ref_Rev_Delay register (From 0 to 255 minutes).
Data Sheet #: TM064 Page 9 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Detailed Description continued
The automatic reference selection is shown in the following state diagram:
Automatic Reference Selection
Figure 6
Stay
Locked on Ref m
time for t=
Ref_Rev_Delay
Ref_Rev_Delay
time expired
Ref n returns,
Ref m marked
“revertive”
Ref n returns,
Ref m marked
“non-revertive”
Select &
Lock on
Ref m
Loss of Ref n
Locked
on Ref n
Select new reference:
Next highest priority,
Qualified (within max. pull-in range, signal present > 10 sec.),
Non-masked
The operational mode is according to the following state diagram:
No available reference and no Hold Over history
Ref loss w/no good Hold Over history and no other available reference
Automatic Operational Mode Selection
Figure 7
Reference Available
(Select highest priority)
Higher priority Ref return with
prior reference marked
“revertive”
Ref Loss w/alternate
reference available
Locked
Ref loss w/no good hold
over history and no other
available reference
Ref Loss w/good hold over history
and no alternate reference available
Ref
Ref
Return
Return
No available
reference and
no hold over
history
Free Run
Hold Over
Data Sheet #: TM064 Page 10 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Detailed Description continued
Output Signals and Frequency
Output 1 is the primary output, and in locked mode is synchronized to the selected reference. Output 1 must be specified at the time
of ordering as any one of the following frequencies : 12.96 MHz, 19.44 MHz, 25.92 MHz, 38.88 MHz, 51.84 MHz or 77.76 MHz.
M/S Output is an 8 kHz output available as a frame reference or synchronization signal for cross-coupled pairs of SM3-IT devices
operated in master/slave mode. In master mode, M/S Output is synchronized to the selected reference. In slave mode, M/S Output is in
phase with the M/S REF offset by the value written to the Phase_offset register (+31.75 to -32nS, with .25nS resolution). M/S Output
may be a 50% duty cycle signal, or variable high-going pulse width, as determined by the Ctl_Mode and Fr_Pulse_Width registers. In
variable pulse width mode, the width may be from 1 to 15 multiples of the Output 1 cycle time. See Register Descriptions and Operation
section.
BITS_Clk is the BITS clock output at either 1.544 MHz or 2.048 MHz. It is selected by the T1/E1 input and its state may be read
in bit 3 of the Ctl_Mode register. When T1/E1 = 1, the BITS frequency is 1.544 MHz, and when T1/E1 = 0, the BITS frequency is
2.048 MHz. This output clock is digitally synthesized from Output1 directly and will be synchronized to M/S Output.
Interrupts
The SM3-IT module supports eight different interrupts and appears in INTR_EVENT (0x12) register. Each interrupt can be individually
enabled or disabled via the INTR_ENABLE (0x13) register. Each bit enables or disables the corresponding interrupt from asserting the
SPI_INT pin. Interrupt events still appear in the INTR_EVENT (0x12) register independent of their enable state. All interrupts are cleared
once INTR_EVENT (0x12) register is read. The interrupts are:
•
•
•
•
•
•
•
•
Any reference changing from available to not available
Any reference changing from not available to available
M/S REF changing from activity to no activity
M/S REF changing from no activity to activity
DPLL Mode status change
Reference switch in automatic reference selection mode
Loss of Signal
Loss of Lock
Interrupts and Reference Change in Autonomous Mode
Interrupts can be used to determine the cause of a reference change in autonomous mode. Let us assume that the module is
currently locked to REF1. The module switches to REF2 and SPI_INT pin is asserted.The user reads the INTR_EVENT (0x12) register.
If the module is operating in autonomous non-revertive mode, the cause can be determined from bits 4, 5, 6 and 7. Bit 5 is set to
indicate Active reference change.If Bit 6 is set then the cause of the reference change is Loss of Active Reference. If Bit 7 is set then the
cause of the reference change is a Loss of Lock alarm on the active reference.
If the module is operating in autonomous revertive mode, the cause can be determined from bits 1, 4,5, 6 and 7. Bit 5 is set to indicate
Active reference change. If Bit 6 is set then the cause of the reference change is Loss of Active Reference.If Bit 7 is set then the cause of
the reference change is a Loss of Lock alarm on the active reference.If Bit 1 is set then the cause of the reference change is the
availability of a higher priority reference.
Note: The DPLL Mode Status Change bit (Bit 4) is also set to indicate a change in DPLL_STATUS (0x11) register, during an interrupt
caused by a reference change. The data in DPLL_STATUS (0x11) register however is not useful in determining the cause of a reference
change. This is because bits 0-2 of this register always reflects the status of the current active reference and hence cannot be used to
determine the status of the last active reference.
Interrupts in Manual Mode
In manual operating mode, when the active reference fails due to a Loss of Signal or Loss of Lock alarm, an interrupt is generated.
For example, in case of a Loss of Signal, bits4 and 6 of INTR_EVENT (0x12) register would be set to indicate Loss of Signal and DPLL
Mode Status Change.The user may choose to read the DPLL_STATUS (0x11) register, though in manual mode bit6 of INTR_EVENT
(0x12) register is a mirror of bit0 of DPLL_STATUS (0x11) register.This holds true for a Loss of Lock alarm, where bit7 of INTR_EVENT
(0x12) register is a mirror of bit1 of DPLL_STATUS (0x11) register.
Internal Clock Calibration
The internal clock may be calibrated by writing a frequency offset v.s. nominal frequency into the Calibration register. This calibration is
used by the synchronization software to create a frequency corrected from the actual internal clock output by the value written to the
Calibration register. See register descriptions.
Data Sheet #: TM064 Page 11 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Descriptions and Operation
Chip_ID_low, 0x00 (R)
Bit 7 ~ Bit 0
Bit 7 ~ Bit 0
Bit 7 ~ Bit 0
Bit 4
Low byte of chip ID: 0x12
Chip_ID_High, 0x01 (R)
High byte of chip ID: 0x30
Chip_Revision, 0x02 (R)
Chip revision number: 0x02
Bandwidth_PBO, 0x03 (R/W)
Bit 7 ~ Bit 5
Reserved
Bit 3 ~ Bit 0
Reserved
0:Default
Bandwidth Selection in Hz:
0000: 0.025
0001: 0.025
0010: 0.025
0011: 0.025
0100: 0.025
0101: 0.025
0110: 0.049
0111: 0.098(Reset Default)
1000: 0.20
1001: 0.39
1010: 0.78
1011 - 1111: 1.6
BITS 3 - 0 select the phase lock loop bandwidth in Hertz.The reset default is 0.098 Hz.
Ctl_Mode, 0x04 (R/W)
Bit 7 ~ Bit 6
Reserved
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Default: 0
M/S Output
Pulse width
control:
0: 50%
1: Controlled by
BITS Clock
Output
Frequency:
1: 1.544 MHz
0: 2.048 MHz
HM Ref:
Active
Reserved
0: Register control
of op mode/ref
(Will always
be 0)
Reference
Selection:
1: Manual
0: Automatic
Default: 1
FR_Pulse_Width (read only)
register
Default: 0
When bit 1 is reset (automatic reference and mode selection), Bits 3 - 0 of the Op_Mode register become read-only.
The power-up default for Bit 1 = 1 for manual reference selection and default for Bit 4 = 0 for 50% duty cycle on M/S Output.
Data Sheet #: TM064 Page 12 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Descriptions and Operation continued
When the device is in slave mode, it will lock to the M/S REF, independent of the values written to BITS 3 - 0 of the Op_mode
register. The operational mode and reference selection written to Bits 3 - 0 while in slave mode will, however, take effect when the
device is made the master.
When bit 1 of the Ctl_Mode register is reset (automatic reference and mode selection) and the device is in master mode, BITS 3 -
0 of the Op_Mode register become read-only.
Op_Mode, 0x05 (R/W)
Bit 7 ~ Bit 5
Reserved
Bit 4
Bit 3 ~ Bit 0
Master or Slave Mode
1: Master
Free Run, Locked, or Hold Over:
0000: Free Run mode
0001: Locked on Ref1
0010: Locked on Ref2
0011: Locked on Ref3
0100: Locked on Ref4
0101 - 1000: Not Used
1001 - 1111: Hold Over
0: Slave
(Read Only)
Max_Pullin_Range, 0x06 (R/W)
Bit 7 ~ Bit 0
Maximum pull-in range in 0.1 ppm unit
This register should be set according to the values specified by the standards (GR-1244) appropriate for the particular stratum of
operation. The power-up default value is 10 ppm. (= 4.6ppm aging + 4.6 ppm pullin + margin).
M/S_Activity, 0x07 (R)
Bit 7 ~ Bit 4
Reserved
Bit 3 ~ Bit 0
Cross reference activity
0000: No signal
0001: 8kHz
0100: 12.96MHz
0101: 19.44MHz
0110: 25.92MHz
0111: 38.88MHz
1000: 51.84MHz
1001: 77.76MHz
1010-1111: Reserved
Indicates signal presence and auto-detected frequency for the M/S REF input.
Ref_Activity, 0x08 (R)
Bit 7
0: off
Bit 6
0: off
Bit 5
0: off
Bit 4
0: off
Bit 3
Bit 2
Bit 1
Bit 0
ref4 activity
1: on
0: off
ref3 activity
1: on
0: off
ref2 activity
1: on
0: off
ref1 activity
1: on
0: off
Each bit indicates the presence of a signal for that reference.
Data Sheet #: TM064 Page 13 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Descriptions and Operation continued
Ref_Pullin_Sts, 0x09 (R)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0: Default
0: Default
0: Default
0: Default
ref4 sts
1: in range
0: out range
ref3 sts
1: in range
0: out range
ref2 sts
1: in range
0: out range 0: out range
ref1 sts
1: in range
Each bit indicates if the reference is within the frequency range specified by the value in the Max_Pullin register.
Ref_Qualified, 0x0a (R)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0: Default
0: Default
0: Default
0: Default
ref4 qual:
1: avail.
ref3 qual:
1: avail.
ref2 qual:
1: avail.
ref1 qual:
1: avail.
0: not avail.
0: not avail.
0: not avail.
0: not avail.
This register contains the “anded” condition of the Ref_Activity and Ref_Pullin_Sts registers for each of the Ref1-4 inputs, quali-
fied for 10 seconds. When a reference signal has been present for > 10 seconds and is within the pull-in range, it’s bit is set.
Ref_Mask, 0x0b (R/W)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0: Default
0: Default
0: Default
0: Default
ref4 mask:
1: avail.
ref3 mask:
1: avail.
ref2 mask:
1: avail.
ref1 mask:
1: avail.
0: not avail.
Default: 0
0: not avail.
Default: 0
0: not avail.
Default: 0
0: not avail.
Default: 0
Individual references may be marked as “available” or “not available” for selection in the automatic reference selection mode
(bit 1 = 0 in the Ctl_Mode register).The reset default value is 0, “not available”. In manual reference selection, either hardware or
register controlled, the reference masks have no effect, but do remain valid and are applied upon a transition to automatic mode.
Ref_Available, 0x0c (R)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0: Default
0: Default
0: Default
0: Default
ref4 avail:
1: avail.
0: not avail.
ref3 avail:
1: avail.
0: not avail.
ref2 avail:
1: avail.
0: not avail.
ref1 avail:
1: avail.
0: not
This register contains the “anded” condition of the Ref_Qualified and Ref_Mask registers.
Ref_Rev_Delay, 0x0d (R/W)
Bit 7 ~ Bit 0
Reference reversion delay time, 0 - 255 minutes. default, 0000 0101, 5 minutes
In automatic reference selection mode, when a reference fails and later returns, it must be available for the time specified in the
Ref_Rev_Delay register before it can be switched back to as the active reference (if the new reference was marked as “revertive”).
See Figure 7.
Data Sheet #: TM064 Page 14 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Descriptions and Operation continued
Phase_Offset, 0x0e (R/W)
Bit 7 ~ Bit 0
The 2’s complement value of phase offset between Master Output module and Slave Output module, ranges from -32 nS to
+31.75 nS
Positive Value: Master Output rising edge leads Slave Output
Negative Value: Master Output rising edge lags Slave Output
In slave mode, the slave’s outputs may be phase shifted -32nS to +31.75nS in .25nS increments, relative to the Master module ac-
cording to the contents of the Phase_Offset register, to compensate for the path length of the Master to Slave connection.
If a phase offset is used, then the two SM3-IT devices would typically be written to the appropriate phase offset values for the re-
spective path lengths of each Master to Slave connection, to ensure that the same relative output signal phases will persist through
master/slave switches.
Calibration, 0x0f (R/W)
Bit 7 ~ Bit 0
2’s complement value of local oscillator digital calibration in 0.05 ppm resolution
To digitally calibrate the free running clock synthesized from the internal clock, this register is written with a value corresponding to
the known frequency offset of the oscillator from the nominal center frequency.
Fr_Pulse_Width, 0x10 (R/W)
Bit 7 ~ Bit4
Bit 3 ~ Bit 0
Reserved
Pulse width for M/S clock output,
1-15 multiples of the Sync_Clk clock period.
BITS 4 and 5 of the Ctl_Mode register determine if the M/S 8 kHz output is 50% duty cycle or pulsed (high going) outputs. When
they are pulsed, the Fr_Pulse_Width register determines the width. Width is the register value multiple of the Sync_Clk clock pe-
riod.Valid values are 1 - 15.
Reset default is 0001. Writing to 0000 maps to 0001.
DPLL_Status, 0x11 (R)
Bit 7 ~Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Reserved
Hold Over
Build
Complete
1: Complete
0: Incomplete
Hold Over
Available
1: Avail.
Locked
1: Locked
0: Not locked
Loss of Lock
1: Loss of Lock
0: No loss of lock
Loss of Signal
1: No activity
on active
0: Not avail.
reference
0: Active ref-
erence signal
present
Bit 0 indicates the presence of a signal on the selected reference.
Bit 1 indicates a loss of lock (LOL). Loss of lock will be asserted if lock is not achieved within the specified time for the stratum level
of operation, or lock is lost after being established previously. LOL will not be asserted for automatic reference switches.
Bit 2 indicates successful phase lock. It will typically be set in <100 seconds for stratum 3 with a good reference. It will indicate “not
locked” if lock is lost.
Bit 3 indicates if a Hold Over history is available.
Bit 4 indicates when a new Hold Over history has been sucessfully built and transferred to the active Hold Over history.
*NOTE: Only references 1 - 4 are used with this model
Data Sheet #: TM064 Page 15 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Descriptions and Operation continued
Intr_Event, 0x12 (R)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Loss of
Lock
Loss of
Signal
Active refer-
ence change
DPLL Mode M/S Ref
M/S Ref
Any refer-
erence change erence change
from not
available to
available
Any refer-
status
Change from Change from
no activity to
activity
change
activity to no
activity
from available
able to not
available
Interrupt state = 1.When an enabled interrupt occurs, the SPI_INT pin is asserted, active low. All interrupts are cleared and the
SPI_INT pin pulled high when the register is read. Reset default is 0.
Intr_Enable, 0x13 (R/W)
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Enable Inter- Enable Inter- Enable Inter-
rupt event 7: rupt event 6: rupt event 5:
Enable Inter- Enable Inter- Enable Inter-
Enable Inter-
rupt event 1:
1: Enable
0: Disable
Default: 0
Enable Inter-
rupt event 0:
1: Enable
0: Disable
Default: 0
rupt event 4: rupt event 3:
rupt event 2:
1: Enable
1: Enable
0: Disable
Default: 0
1: Enable
0: Disable
Default: 0
1: Enable
0: Disable
Default: 0
1: Enable
0: Disable
Default: 0
1: Enable
0: Disable
Default: 0
0: Disable
Default: 0
Enables or disables the corresponding interrupts from asserting the SPI_INT pin. Interrupt events still appear in the Intr_Event reg-
ister independent of their “enable” state. Reset default is interrupts disabled.
Ref(1-4)_Frq_Offset, 0x14 ~ 0x17(R)
Bit 7 ~ Bit 0
2’s complement value of frequency offset between reference and calibrated local oscillator, 0.2ppm resolution
These registers indicate the frequency offset, in 0.2ppm resolution, between each reference and the local calibrated oscillator.
0x14 - 0x17 correspond to Ref1 - Ref4.
Ref(1-4)_Frq_Priority, 0x1c ~ 0x1f (R/W)
Bit 7 ~ Bit 4
Bit 3
Bit 2 ~ Bit 0
Frequency
0000: None
0001: 8 kHz
Revertivity
Priority
1: revertive
0: non-revertive
Default: 0,
0: highest
3: lowest
Default: 0
0010: 1.544 MHz
0011: 2.048 MHz
0100: 12.96 MHz
0101: 19.44 MHz
0110: 25.92 MHz
0111: 38.88 MHz
1000: 51.84 MHz
1001: 77.76 MHz
non revertive
1010-1111: Reserved
BITS 2 - 0 indicate the priority of each reference for use in automatic reference selection mode (bit 1 of the Ctl_Mode register =0). In
manual reference selection mode (bit 1 of the Ctl_Mode register = 1), these BITS are read-only and will contain either the reset de-
fault or values written when last in automatic reference selection mode. For equal priority values, lower reference numbers have
higher priority.
Bit 3 specifies if the reference is revertive or non-revertive in automatic reference selection mode. When a reference fails, the next
highest priority “available” (signal present, non-masked, and acceptable frequency offset) reference will be selected.When a refer-
ence returns, it will be switched to only if it is of higher priority and the current active reference is marked “Revertive”.
BITS 7 - 4 indicate the auto-detected frequency for each reference. Invalid frequencies may result in erroneous device operation. If
there is no activity on a reference, bits 7-4will be = 0000. Bits 7-4 are read only. 0x1c - 0x1f correspond to Ref1 - Ref4.
Data Sheet #: TM064 Page 16 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Descriptions and Operation continued
FreeRun_Priority, 0x24 (R/W)
Bit 7 - Bit 5
Bit 4
Bit 3
Bit 2 - Bit 0
Enable/
Disable
1: Enable
0: Disable
Default: 0
Revertivity
1: Enable
0: Disable
Default: 0
Priority
0: Highest
3: Lowest
Default: 0
Reserved
non-revertive
Free Run may be treated like a reference. When it is enabled, Free Run will be entered when all references of higher priority are lost
or masked. If or when a higher priority reference returns, it is switched to if Free Run is set as “revertive”. When disabled, Free Run
will be entered only if manually selected or all references fail without an available Hold Over history. For equal priority value, Free
Run will be treated as lower priority.
History_Policy, 0x25 (R/W)
Bit 7 - Bit 1
Reserved
Bit 0
Reference Switch Hold Over
Hisory Policy
0: Rebuild
1: Continue
Bit 0 determines if Hold Over is retained or rebuilt when a reference switch occurs. SeeApplication Notes, Holdover
History Accumulation and Management section.
History_Cmd, 0x26 (R/W)
Bit 7 - Bit 2
Reserved
Bit 1-0
Hold Over Histroy Commands
01: Save active history to backup history
10: Restore active history from backup
11: Flush the active history and accumulation register
00: No command - use to write Bit4 to change policy
Bits 0-1 are written to save a holdover history to the backup history, restore the active holdover history from the
backup, or flush the active history. The default value of the register is 00.The last command is latched and
may be read by the application. A flush does not affect the backup history. See Application Notes, Holdover
History Accumulation and Management section.
HoldOver_Time, 0x27 (R)
Bit 7 - Bit 0
Indicates the time since entering the Hold Over state. from 0-255, one bit per hour. Zero in non-Hold Over state and stops at 255.
Cfgdata, 0x30 (R/W)
Bit 7 - Bit 0
Configuration data write register.
Configuration data is written to this register. Internal use only.
Cfgctr_Lo, 0x31 (R)
Bit 7 - Bit 0
Configuration data write counter low byte.
Low order byte of configuration data write counter. Internal use only.
Data Sheet #: TM064 Page 17 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Register Descriptions and Operation continued
Cfgctr_Hi, 0x32 (R)
Bit 7 - Bit 0
Configuration data write counter high byte.
High order byte of configuration data write counter. Internal use only.
Chksum, 0x33 (R/W)
Bit 7 - Bit 1
Bit 0
Configuration Data Checksum
pass/fail indicator
0: Fail
Reserved
1: Pass
Checksum verification register for configuration data. Internal use only.
EE_Mode, 0x36 (R/W)
Bit 7 - Bit 1
Bit 0
EEPROM Write Enable
0: Disable
Reserved
1: Enable
EEPROM write enable register.
EE_Cmd, 0x37 (R/W)
Bit 7
Bit 6 - Bit 2
Reserved
Bit 1 - Bit 0
EEPROM read/write
ready bit:
0 = Not Ready
1 = Ready
EEPROM read/write command bits:
00 = Reset FIFO
01 = Write Command
10 = Read Command
EEPROM read/write command register.
EE_Page_Num, 0x38 (R/W)
Bit 7 - Bit 0
EEPROM read/write page number, 0x00 to 0x9f (0 - 159)
EEPROM read/write page number register. EEPROM consist of 160 pages.
EE_FIFO_Port, 0x39 (R/W)
Bit 7 - Bit 0
EEPROM read/write FIFO data.
EEPROM read/write FIFO port register. EEPROM data is written to/read from this location.
Data Sheet #: TM064 Page 18 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Performance Specifications
Performance Definitions
Jitter and Wander – Jitter and wander are defined respectively as “the short-term and long-term variations of the significant instants
of a digital signal from their ideal positions in time”.They are therefore the phase or position in time modulations of a digital signal relative
to their ideal positions. These phase modulations can in turn be characterized in terms of their amplitude and frequency. Jitter is defined
as those phase variations at rates above 10Hz, and wander as those variations at rates below 10Hz.
Fractional frequency offset and drift – The fractional frequency offset of a clock is the ratio of the frequency error (from the nominal
or desired frequency) to the desired frequency.It is typically expressed as (n parts in 10X), or (n x 10-X). Drift is the measure of a clock’s
frequency offset over time. It is expressed the same way as offset.
Time Interval Error (TIE) – TIE is a measure of wander and is defined as the variation in the time delay of a given signal relative to an
ideal signal over a particular time period. It is typically measured in nS. TIE is set to zero at the start of a measurement, and thus
represents the phase change since the beginning of the measurement.
Maximum Time Interval Error (MTIE) – MTIE is a measurement of wander that finds the peak-to-peak variations in the time delay of
a signal for a given window of time, called the observation interval (t).Therefore it is the largest peak-to-peak TIE in any observation
interval of length t within the entire measurement window of TIE data. MTIE is therefore a useful measure of phase transients, maximum
wander and frequency offsets. MTIE increases monotonically with increasing observation interval.
Time Deviation (TDEV) – TDEV is a measurement of wander that characterizes the spectral content of phase noise. TDEV(t is the
RMS of filtered TIE, where the bandpass filter is centered on a frequency of 0.42/t.
SM3-IT Performance
Input JitterTolerance – Input jitter tolerance is the amount of jitter at its input a clock can tolerate before generating an indication of
improper operation. GR-1244 and ITU-813 requirements specify jitter amplitude v.s. jitter frequency for jitter tolerance. The SM3-IT device
provides jitter tolerance that meets the specified requirements.
Input WanderTolerance – Input wander tolerance is the amount of wander at its input a clock can tolerate before generating an
indication of improper operation. GR-1244 and ITU-813 requirements specify input wander TDEV vs. Integration Time as shown below.
Integration Time, (seconds)
0.05 ≤ τ < 10
TDEV (ns)
100
0.5
10 < τ < 1000
31.6 x τ
1000 ≤ τ
N/A
The SM3-IT device provides wander tolerance that meets these requirements.
PhaseTransientTolerance – GR-1244 specifies maximum reference input phase transients that a clock system must tolerate without
generating an indication of improper operation. The phase transient tolerance is specified in MTIE(nS) v.s. observation time from .001 to
100 seconds, as shown below.
Observation time S (Seconds)
0.001326 ≤ S < 0.0164
0.0164 < S < 1.97
MTIE (ns)
61,000 x S
925 + 4600 x S
10,000
1.97 ≤ S
The SM3-IT will tolerate all reference input transients within the GR-1244 specification.
Free Run Frequency Accuracy – Free Run frequency accuracy is the maximum fractional frequency offset while in Free Run mode.
It is determined by the accuracy of the internal clock.
Hold Over Frequency Stability – Hold Over frequency stability is the maximum fractional frequency offset while in Hold Over mode.
It is determined by the stability of the internal clock.
Data Sheet #: TM064 Page 19 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Performance Specifications continued
Wander Generation– Wander generation is the process whereby wander appears at the output of a clock in the absence of input
wander. The SM3-IT wander generation characteristics, MTIE and TDEV, are shown below, along with the requirements masks
(bandwidth = 0.098 Hz):
Wander Generation Characteristics – MTIE
1000
GR-1244-CORE, R5-5
100
10
1
0.1
1
10
100
1000
10000
100000
Observat ion Time (sec)
Wander Generation Characteristics – TDEV
100
10
GR-1244-CORE, R5-4
1
0.1
0.01
0.01
0.1
1
10
100
1000
10000
100000
Integration Time (sec)
Data Sheet #: TM064 Page 20 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Performance Specifications continued
WanderTransfer – Wander transfer is the degree to which input wander is attenuated (or amplified) from input to output of a clock.
The GR-1244 requirements for wander transfer limits are shown below.
Integration time, τ (seconds)
τ < 0.05
Stratum 3 TDEV (nanoseconds)
N/A
1020 x τ
102
0.05 ≤ τ < 0.1
0.1 ≤ τ < 1.44
1.44 ≤ τ < 10
10 ≤ τ < 300
102
0.5
32.2 x τ
0.5
300 ≤ τ ≤ 1000
1000 < τ
32.2 x τ
N/A
The SM3-IT, when configured for the appropriate stratum 3 bandwidth frequency, meets the stratum 3 requirements,
Jitter Generation – Jitter generation is the process whereby jitter appears at the output of a clock in the absence of input jitter.
The device jitter generation performance is as shown below:
Jitter
19.44 MHz
8 ps Typical
77.76 MHz
8 ps Typical
Broadband
(10 Hz - 2 MHz)
SONET Band
(12 kHz -2MHz)
5 ps Typical
(12 kHz -20MHz)
1.5 ps Typical
Jitter Transfer – Jitter transfer is the degree to which input jitter is attenuated (or amplified) from input to output of a clock. It is
a function of the selected bandwidth.
PhaseTransients – A phase transient is an unusual step or change in the phase-time of a signal over a relatively short time period.
This may be due to switching between equipment, reference switching, diagnostics, entry or exit to/from Hold Over, or input reference
transients. The SM3-IT performance for reference switches is shown below:
Phase Transients – MTIE
10000
GR-1244-CORE,R5-14
1000
100
10
1
0.001
0.01
0.1
1
10
100
1000
Observation Time (sec)
Data Sheet #: TM064 Page 21 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Performance Specifications continued
Capture range and Hold range – Capture range and Hold range are the maximum frequency errors on the reference input within which
the phase locked loop is able to achieve lock and hold lock, respectively. The SM3-IT stratum 3 performance is shown below:
Characteristic
Capture range
Hold range
SM3-IT
Requirement
± 50 ppm maximum
± 50 ppm maximum
GR-1244-CORE, Sec 3.4
GR-1244-CORE, Sec 3.4
This is the minimum capability, and guarantees the ability to capture and lock with a reference that is offset the maximum allowed in one
direction in the presence of a clock that is offset the maximum in the opposite direction (4.6 ppm + 4.6 ppm = 9.2 ppm).
Master/Slave Skew and Reference switch settling time– Master/Slave Skew and Reference switch settling time performance are
shown below:
Characteristic
SM3-IT
< 2 nS
Requirement
N/A
Master/Slave phase skew
Reference switch settling time
Stratum 3: < 100 sec. up to 20 ppm
frequency offset
Stratum 3: < 100 sec. up
to +/- 4.6 ppm frequency offset
SM3-IT Initialization:
Power-up:
1. If possible, always start up in master mode. After the module is powered up, hold the reset pin low for 10ms. Wait 1200ms and
read the contents of register 0x33. If it reads1 then the module came up properly. If it reads 0 then reset the module and re-read
register 0x33 after 1200ms. The contents of 0x33 must read 1 before continuing.
2. Remain in the default free-run mode for 10 seconds then read the value of bit 1 of register 0x11 or pin 2, the LOL alarm output.
If the LOL alarm is set, the reset pin must be pulled low as in 1 above. In the free-run mode the LOL alarm should never be set.
This indicates the module is in an invalid state. If there is no LOL alarm in free-run the module is ready.
Operation:
On power up or after a reset all the registers are loaded with their default values. The default values of some important registers
are given below assuming the module operates as a Master.
Address(Hex) Register Name
Value(Binary MSB first) Notes
0x03
0x04
0x05
0x06
0x0b
0x0d
0x0e
0x0f
0x11
0x13
0x1c-0x1f
0x33
Bandwidth_PBO
Ctl_Mode
Op_Mode
Max_Pullin_Range
Ref_Mask
Ref_Rev_Delay
Phase_Offset
Calibration
DPLL_Status
Intr_Enable
Ref(1-4)_Frq_Priority
Chksum
00000111
0000r010
00010000
01100100
00000000
00000101
00000000
00000000
00000000
00000000
xxxx0000
xxxxxxx1
Bandwidth = 0.098Hz
r - Read Only
Indicates Free Run mode
Indicates No Active Reference
Indicates Interrupts are disabled
Frequencies are auto detected
Bit0 should be high to indicate that data has been loaded
correctly from the EEPROM.
Data Sheet #: TM064 Page 22 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
I. The unit starts up in Free Run and operates in Manual mode. Here are the steps that need to be taken to lock the unit to a
reference in Manual mode.
1.
2.
3.
4.
5.
Apply signal to the reference inputs.
Set the appropriate pull in range by writing to address 0x06.
A value of 0001xxxx, depending on which (Ref 1-4) reference to lock to, should be written to address 0x05.
Enable Reference mask for appropriate references by writing a 1 to the reference bit in address 0x0b.
Enable all Interrupts by writing 1111 to address 0x13.
II. To lock the unit to a reference in autonomous (automatic) mode after power up or reset, the following steps should be taken.
You can also switch from Manual to Autonomous mode directly. When doing so, please ensure that the appropriate references are
available by checking REF_AVAILABLE register (address: 0x0c).
1.
2.
3.
4.
5.
6.
Clear bit1 of CTL_MODE register (address: 0x04). This puts the module in autonomous mode.
Apply signal to the reference inputs
Set the appropriate pull in range by writing to address 0x06
Enable Reference mask for appropriate references by writing a 1 to the reference bit in address 0x0b.
Set priority and revertivity for the input references by writing to the appropriate Ref_Frq_Priority registers (bits 3-0).
Enable all Interrupts by writing 1111 to address 0x13.
7.
Set the unit to operate in autonomous mode by clearing bit1 of address 0x04
III. Slave Mode Operation:
1.
2.
3.
4.
5.
As a Slave, the module operates in Autonomous mode.
The Bandwidth is set, by default, to 1.6Hz (Bandwidth_PBO register (Address 0x03): 00001011).
Note that Bit 4 of the OP_MODE register (Address 0x05) is cleared.
The values in Bits 3-0 of this register have no effect on the operation of the Slave module.
For the Slave module to track the Master accurately, an appropriate Phase Offset value should be written to
PHASE_OFFSET register (Address 0x0e) is used to compensate for the path delay.
The module will lock to the Cross Reference Input (XREF) from the master.
6.
IV RESET Parameters:
1.
2.
The reset pin should be held low for a minimum of 10 milliseconds to ensure a complete reset occurs.
The SPI interface should not be accessed for a minimum of 1200ms after the reset pin is de-asserted.
Switching Master/Slave designations:
The following steps need to be taken before making Master module a Slave and vice versa.
1.
2.
3.
Copy the value in the PHASE_OFFSET register (Address 0x0e) of the Slave to the Master module's PHASE_OFFSET
regsiter (Address 0x0e).
Read the contents of Bits 3-0 of the Master's OP_MODE register (Address 0x05) and copy it into Bits 3-0 of the Slave's
OP_MODE register (Address 0x05).
It is recommended that the contents of REF(1-4)_FRQ_PRIORITY registers (Address 0x1c-0x1f) and REF_MASK
register (Address 0x0b) from Master be copied to Slave to ensure seamless Master/Slave switches. Master/Slave
switches should be performed with minimal delay between switching the states of each of the two devices.
Data Sheet #: TM064 Page 23 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Application Notes
Acceptable output frequencies are: 12.96 MHz, 19.44 MHz, 25.92 MHz, 38.88 MHz, 51.84 MHz or 77.76MHz. The device will
autodetect the output frequency.
Reference Inputs – The application may supply up to 4 reference inputs, applied at input pins Ref1 - 4. They may each be 8 kHz,
1.544 MHz, 2.048 MHz, 12.96 MHz, 19.44 MHz, 25.92 MHz, 38.88 MHz, 51.84 MHz or 77.76 MHz. The device auto-detects the
reference frequencies, and they may be read from the Ref(1-4)_Frq_Priority registers in register control mode, as described in the control
mode sections that follow.
Reference switches are performed in a hitless manner. However, if the application externally changes the frequency of a particular
reference, the device requires 20ms to auto-detect the new frequency. Manual switches to a frequency changed reference should not be
made during this interval. Automatic reference selection mode accounts for the auto-detection in the reference qualification.
References would typically (but need not be) connected in decreasing order of usage priority. For example if redundant BITS clocks
are available, they would typically be assigned to Ref1 and Ref2, with other transmission derived signals following thereafter.
Master/Slave operation – For some applications, reliability requirements may demand that the clock system be duplicated.The SM3-
IT device will support the master/slave duplicated configuration for such applications. To facilitate it’s use, the device includes the
necessary signal cross coupling and control functions. Redundancy for reliability implies two major considerations: 1) Maintaining
separate failure groups such that a failure in one group does not affect it’s mate, and 2) Physical and logical partitioning for repair, such
that a failed component can be replaced while the mate remains in service, if so desired. System design needs to account to meet
system level goals.
Master / Slave Configuration
Figure 8
SM3
#1
REF1
REF1
BITS clock output
BITS_CLK
REF4
REF4
OUTPUT1
M/S_OUT
Synchronized clock output
Master/Slave output
M/S REF
M/S REF
REF1
M/S_OUT
OUTPUT1
BITS_CLK
Master/Slave output
Synchronized clock output
BITS clock output
SM3
#2
REF4
Data Sheet #: TM064 Page 24 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Application Notes continued
Master/Slave Configuration – A pair of devices are interconnected by cross-coupling their respective M/S Outputs or Output1 to
the other device’s M/S REF input (See Figure 8). Additionally, the reference inputs for each device would typically be correspondingly the
same, so that when a Master/Slave switch occurs, synchronization would continue with the same reference. The references may be
driven by the same signal directly or via separate drivers, as the redundancy of that part of the system requires. Distribution path lengths
are not critical here, as a phase build-out will occur when a device switches from slave to master.
The path lengths of the two M/S Output to M/S REF signals is of interest, however. They need not be the same. However, to
accommodate path length delays, the SM3-IT provides a programmable phase skew feature, which allows the application to offset the
output clock from the cross-reference signal by -32ns to +31.75ns. This offset may therefore be programmed to exactly compensate for
the actual path length delay associated with the particular application’s cross-reference traces. The offset may be further adjusted to
accommodate any output clock distribution path delay differences.Phase offset is programmed by writing to the Phase_Offset register,
and is typically a one-time device initialization function. (See register description and Register Access Control sections).Thus, master/
slave switches with the SM3-IT devices may be accomplished with near-zero phase hits.
For applications that use Hardware Control only (i.e. phase offset programming is not available), it is desirable to keep the cross
couple path lengths at a minimum and relatively equal in length, as the path length will appear as a phase hit in the slave clock output
when a master/slave switch occurs in a Hardware Control configuration.
Master/Slave Operation and Control – The Master/Slave state is always manually controlled by the application. Master or slave
state of a device is determined by the MASTER SELECT pin. Choosing the master/slave states is a function of the application, based on
the configuration of the rest of the system and potential detected fault conditions.
When operating in Hardware Control or Register Access Manual Control mode, it is important to set the slave reference selection the
same as the master to ensure use of the same reference when/if the slave becomes master. In Register Access Manual Control mode,
the Ref_Mask register should also be written to the same value for both devices.
Master/slave switches should be performed with minimal delay between switching the states of each of the two devices. This can be
easily accomplished, for example, by controlling the master/slave state with a single signal, coupled to one of the devices through an
inverter.
In the case of Register Access Automatic Control mode, where reference selection is automatic, it is necessary to read the
operational mode BITS 3-0) from the master’s Op_Mode register and write it to the slave’s Op_Mode register. The master’s reference
selection will then be used by the slave when it becomes master. In addition to having the references populated the same, and in the
same order for both devices, it is desireable to write the reference frequency and priority registers Ref(1-4)_Frq_Priority and the
Ref_Mask registers to the same values for both devices to ensure seamless master/slave switches.
Reset – Device reset is an initialization time function, which resets internal logic and register values. A reset is performed
automatically when the device is powered up. Registers return to their default values, as noted in the register descriptions. Device mode
and functionality following a reset are determined by the state of the various hardware control pins.
Holdover History Accumulation and Maintenance -- Holdover history accumulation and maintenance may be controlled in greater
detail if register bus access to the device is provided. Holdover history accumulation and control encompasses three device internal
registers, three bus access registers for control and access, and two status bits in the DPLL_Status register.
Hold Over History
Active
Accumulation Register
Hold Over History
Backup
Hold Over History
Once lock has been achieved, holdover history is compiled in the accumulation register. It is transferred to the Active holdover history
when it is ready (typically in about 15 minutes).The “Holdover Available” bit and output pin are set to “1”. From then on, the Active
holdover history is continually updated and kept in sync with the holdover history accumulation register.(See Figure 11).
Data Sheet #: TM064 Page 25 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Application Notes continued
Hold Over History access and Control Registers
Table 5
Register
0x25
Register Name
History_Policy
History_Cmd
Description
Sets policy for Hold Over history accumulation:“Rebuild” or “Continue”
Save, restore, and flush commands for Hold Over history
Indicates the time since entering the Hold Over state
Bits 3 and 4: Hold Over Available” and “Hold Over Build Complete”
0x26
0x27
Holdover_Time
DPLL_Status
0x11
Hold Over History and Status States
Figure 9
Flush
Reference Switch
Acquire Reference
Hold Control = 0
Hold Available = 0
Reference Lock
Reference Switch
Flush
Build History
Hold Control = 0
Hold Available = 0
Flush
History Build Complete
Locked, History
Complete
Hold Control =1
Hold Available = 1
Reference Lock
(with "Continue" set)
Reference Switch
History Build
Complete,
Replace Active
Acquire Reference
Hold Control = 0
Reference Switch
Hold Available = 1
Hold Over History
Reference Lock
(with "Rebuild" set)
Reference Switch
Build History
Hold Control = 0
Hold Available = 1
History Restored from backup,
re-start the building procedure.
Data Sheet #: TM064 Page 26 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Application Notes continued
Whenever holdover is entered, it is the Active Holdover History that is used to determine the holdover frequency. The History_Cmd
register allows the application to issue three holdover history control commands:
1) Save the Active Holdover History to the Backup History.
2) Restore a Backup History to the Active.
3) Flush the active History as well as the accumulation register. The Backup history remains intact.
Both the Active and the Backup holdover histories are loaded with the calibrated freerun synthesizer control data on reset/power-up.
The application might use the “save to backup” in a situation where, for example, the primary reference is known to be of higher
quality than any secondary references, in which case it may be desirable to save and then restore the holdover history accumulated on
the primary reference if the primary reference is lost and holdover is entered upon loss of a secondary reference. Users can restore the
history from backup any time, even while operating in Holdover mode. The frequency transient will be smooth and continuous. It is the
responsibility of application software to keep track of the age and viability of the holdover backup history. Given time and temperature
effects on oscillator aging, the application may wish to periodically perform a “Save” of the Active history to keep the backup current.
When switching to a new reference, the active holdover history will remain intact and marked as “Holdover Available” (if it was
available before the reference switch) until a new history is accumulated on the new reference (Typically 15 minutes after lock has been
achieved). During the new history accumulation, the “Holdover Build Complete” bit is reset. Once the new history accumulation is
complete, it is transferred to the Active History and the “Holdover Build Complete” bit is set.The active history will then continue to be
updated to track the reference.
The History_Policy register allows the application to control how a new history is built.When set to “Rebuild”:
1) History accumulation begins when lock is achieved on the new reference.
2) The holdover history is rebuilt (taking about 15 minutes).The Active History remains untouched until it is replaced when the build is
complete.
When the policy is set to “Continue”:
1) If there is no “Available” Active History, a new build occurs, as under the “Rebuild” policy.
2) If there is an “Available” Active History, it will continue, the accumulation register will be loaded from the
Active History, and the “Build” process is essentially completed immediately following lock on the new reference.
The “Continue” policy may be used by the application if, for example, it is known that the reference switched to may be traced to the
same source and therefore likely has no frequency offset from the prior reference.In that case, the “Continue” policy avoids the delay of
rebuilding the holdover history. If the switch is likely to be between references with known or unknown frequency offset, then it is
preferable to use the “Rebuild” policy.
The time since the holdover state was entered may be read from the Holdover_Time register. Values are from 0 to 255 hours, limited
at 255, and reset to 0 when not in the holdover state.
Boundary scan – The SM3-IT provides a standard IEEE 1149.1 JTAG boundary scan interface via theTMS, TCK, TDI, TDO, and
TRST pins. Boundary scan may be used to verify proper device I/O connectivity and functionality.
Control Modes
The device can in turn be operated in a manual control mode, or automatic control and reference selection mode.
Reset may be pulled low for a minimum of 100nS during SM3-IT start-up (or any other desired time) to initialize the full device state.
However, power-up will also perform a reset, so in a minimal configuration, Reset input may be tied high.
The BITS clock output frequency is selected by the T1/E1 pin.When T1/E1 = 1, the BITS frequency is 1.544 MHz, and when T1/E1 =
0, the BITS frequency is 2.048 MHz.
MASTER SELECT - Determines the master or slave mode. Set to “1” for a master, and “0” for a slave. Master/slave switches should
be performed with minimal delay between switching the states of each of the two devices. This can be easily accomplished, for example,
by controlling the master/slave state with a single signal, coupled to one of the devices through an inverter.
For simplex operation, the device should be in Master mode - set MASTER SELECTto “1”.
Data Sheet #: TM064 Page 27 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Application Notes continued
Mechanical Dimensions
Figure10
1.450 [36.83mm]
MAX.
.075 [1.91mm]
1.000 [25.40mm]
MAX.
.850 [21.59mm]
Pin 1 Indicator
.125 [3.17mm]
.515 [13.08mm]
MAX.
.070 [1.78mm]
.100 [2.54mm]
.018 [.45mm]
Footprint Dimensions
Figure 11
TOP VIEW
1.050
0.950
HOLE/PAD SIZE (28 PLACES):
CUSTOMER COMPONENT
KEEP OUT AREA
1. UNSOCKETED MODULE:
0.028" DIA. PLATED HOLE WITH 0.060" DIA. PAD.
2. SOCKETED MODULE:
0.038" DIA. PLATED HOLE WITH 0.070" DIA. PAD.
PIN 1
NOTE: For compatibllity with both the unsocketed and
socketed modules, Connor-Winfield recommends using a
0.038" DIA. plated hole with 0.070" DIA. pad
0.100
0.000
Data Sheet #: TM064 Page 28 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Application Notes continued
Required External Components
1. Place series resistors (33 ohms) on all reference inputs (Pins 4 - 7).
2. Place series resistors (33 ohms) on SPI_IN and SPI_CLK inputs (Pins 21, 22).
3. Place one .01uF and one 47-100uF capacitor at the input power pin (Pin 23).
4. One 4.7uF (25V) capacitor is required at the VPP pin (Pin 14).
5. One 4.7uF (25V) capacitor is required at the VPN pin (Pin 15).
PCB Layout Recommendations
1. Orient module so airflow is parallel along the header strips (pins).
2. Place de-coupling and/or filter components as close to module pins as possible.
3. Do not place any components directly beneath the module on the topside of the host PCB.
4. Ensure that only clean and well-regulated power is supplied to the module.
5. Isolate power and ground inputs to the module from noisy sources.
6. Provide power and ground connections through a 0.050" wide trace (minimum) using 1-oz. Cu or equivalent copper feature (i.e.
internal plane, copper area fill, etc.).
7. Keep module signals away from sensitive or noisy analog and digital circuitry.
8. Avoid split ground planes as high-frequency return currents may be affected.
9. Allow extra spacing between traces of high-frequency inputs and outputs.
10.Keep all traces as short as possible - avoid meandering trace paths.
11.Avoid routing signals directly beneath the module on the topside of the host PCB.
12.If possible, provide a copper area directly beneath the module on the topside of the host PCB. Connect this copper area to
ground.
13.It is recommended that the connections of the JTAG, VPP and VPN pins be routed to pads, preferably in a SIL pattern as shown
in Figure 13 below. It is recommended to use 0.1” center to center spacing.
1
8
Figure 13
Optional Socket Mounting Recommendations
Mating sockets may be used if permanent installation of the SM3-IT module is not desired. Two possible sources for these sockets
include:
1.
2.
Samtec, "Low Profile Socket Strips", SL Series, PN SL-114-G-19. (http://www.samtec.com/)
Mill-Max, "Single-In-Line Sockets", 315 Series, PN 315-xx-114-41-001. (http://www.mill-max.com/)
The SM3-IT requires two 14-pin sockets. The optional dual footprint configuration shown in Figure 13 requires one 14-pin and two
16-pin sockets.
Data Sheet #: TM064 Page 29 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Application Notes continued
Optional SM3-IT/SM3E Dual Footprint
A dual footprint configuration may be used when designing a host circuit board containing the Connor Winfield SM3-IT or SM3E
modules. The smaller SM3-IT contains a subset of the signal pins found on the larger SM3E in locations which allow for a simple
dual footprint arrangement like the one shown in Figure 13.
SM3EG5
32
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
LOS
LOL
MASTER SELECT
SPI_INT
SPI_OUT
RESET
SM3G5
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
2
3
M/S REF
REF1
4
5
REF2
SPI_ENBL
Vcc
6
REF3
7
REF4
SPI_IN
SPI_CLK
GND
(TOP VIEW)
8
TDI
9
TMS
10
11
12
13
14
15
16
TRST
TCK
BITS_CLK
M/S_OUT
OUTPUT1
VPP
TDO
HOLD_GOOD
T1/E1
VPN
REF5
REF7
REF6
REF8
0.850"
1.100"
Figure 12
The modules shown in Figure 13 are arranged in a left-justified fashion. Notice that right justified or center justified (with an
additional column of SM3-IT pins) arrangements are also possible, depending on the designer's preference.
Placement of external components
1.
2.
3.
4.
5.
Place series resistors (33 ohms) on all reference input (SM3-IT Pins 4 - 7, SM3E Pins 4-7 & 15-18).
Place series resistors (33 ohms) on SPI_IN and SPI_CLK inputs (SM3-IT Pins 21,22, SM3E Pins 25 & 26).
Place one .01uF and one 47-100uF capacitor at the input power pin (SM3-IT Pin 23, SM3E Pin 27).
One 4.7uF (25V) capacitor is required at the VPP pin (SM3-IT & SM3E Pin 14).
One 4.7uF (25V) capacitor is required at the VPN pin (SM3-IT Pin 15, SM3E Pin 19).
Be sure to consult Connor Winfield's respective datasheets for additional mechanical, electrical, footprint and keep-out information.
Data Sheet #: TM064 Page 30 of 32 Rev: 01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
Ordering Information
SM3-IT-XXX.XXM
Replace XXX.XX with one of the following available frequencies,
012.96MHz, 019.44MHz, 025.92MHz, 038.88MHz, 051.84MHz or 077.76MHz.
Please contact Connor-Winfield for other frequencies that may be available.
Similar Products from Connor-Winfield
SM3-XXX.XXM - Stratum 3 module with 4 input references.
SM3-8R-XXX.XXM - Stratum 3 module with 8 input references.
SM3E-XXX.XXM - Stratum 3E module with 8 input references.
Data Sheet #: TM064 Page 31 of 32 Rev:01 Date: 10/15/07
© Copyright 2007 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice
2111 Comprehensive Drive
Aurora, Illinois 60505
Phone: 630-851-4722
Fax: 630- 851-5040
www.conwin.com
Revision
00
Revision Date
08/23/04
Note
Final Release Data Sheet
Add Initialization Info, Pg. 22-23
01
10/15/07
相关型号:
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