SM3 Datasheet, PDF (23/36 Pages) Connor-Winfield Corporation – ULTRA MINIATURE STRATUM 3 MODULE

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 stratum 3 performance is shown below:
Characteristic
Capture range
Hold range
Maximum
SM3
± 50 ppm maximum
± 50 ppm maximum
Requirement
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
Master/Slave phase skew
Reference switch settling time
SM3
< 2 nS
Stratum 3: < 100 sec. up to 20 ppm
frequency offset
Requirement
N/A
Stratum 3: < 100 sec. up
to +/- 4.6 ppm frequency offset
SM3 Initialization:
After the module is powered up, pull the reset pin low for 10ms. Wait 1200ms and read the contents of register 0x33. If it reads
1 then the module came up properly. If it reads 0 then reset the module and re-read register0c33 after 1200ms. The contents of
0x33 must read 1 before using the module. 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 SM3 module operates as a Master
Address(Hex)
0x03
0x04
0x05
0x06
0x0b
0x0d
0x0e
0x0f
0x11
0x13
0x1c-0x23
0x33
Register Name
Bandwidth_PBO
Ctl_Mode
Op_Mode
Max_Pullin_Range
Ref_Mask
Ref_Rev_Delay
Phase_Offset
Calibration
DPLL_Status
Intr_Enable
Ref(1-8)_Frq_Priority
Chksum
Value(Binary MSB first) Notes
00000111
Bandwidth = 0.098Hz
0000r010
r - Read Only
00010000
Indicates Free run mode
01100100
00000000
00000101
00000000
00000000
00000000
Indicates No Active Reference
00000000
Indicates Interrupts are disabled
xxxx0000
Frequencies are auto detected
xxxxxxx1
Bit0 should be high to indicate that data has been loaded
correctly from the EEPROM.
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. Apply signal to the reference inputs.
2. Set the appropriate pull in range by writing to address 0x06.
3. A value of 0001xxxx, depending on which (Ref 1-8) reference to lock to, should be written to address 0x05.
4. Enable Reference mask for appropriate references by writing a 1 to the reference bit in address 0x0b.
5. Enable all Interrupts by writing 11111111 to address 0x13.
Data Sheet #: TM052 Page 23 of 36 Rev: 03 Date: 11/07/08
© Copyright 2008 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice