stc3800 Connor-Winfield VCXOs, stc3800 Datasheet - Page 37

• Manufacturer Part Number: stc3800
• Description: Integrated - Stratum 3e Timing Source
• Manufacturer: Connor-Winfield VCXOs

Application Notes continued
controlled in greater detail if register bus access to the device is provided. Hold Over 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 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 Hold Over history is continually updated and kept in sync with the Hold Over history
accumulation register. (See Figure 12).
Hold Over History Accumulation and Maintenance
Once lock has been achieved, Hold Over history is compiled in the accumulation register. It is transferred to the Active
0x25
0x26
0x27
0x11
History_Policy
History_Cmd
Hold Over_Time
DPLL_Status
accumulation register
Hold Over History Access and Control Registers
Holdover History
© Copyright 2001 The Connor-Winfield Corp. All Rights Reserved
Preliminary Data Sheet #: TM061
Save, restore, and flush commands for Hold over history
Bits3 and 4: “Hold Over Available” and “Hold Over Build Complete”
Sets policy for Hold Over history accumulation: “Rebuild” or “Continue”
Indicates the time since entering the Hold Over state
– Hold Over history accumulation and maintenance may be
Table 11
Active Holdover
Backup Holdover
History
History
Page 37 of 48
Specifications subject to change without notice
Rev: P06 Date: 11/22/04