STC3800 Datasheet, PDF (40/48 Pages) Connor-Winfield Corporation – INTEGRATED - STRATUM 3E TIMING SOURCE

Application Notes continued
Control Modes
The STC3800 device may be controlled and interfaced in a pure hardware mode with pin signals, or via SPI or parallel
bus/register access. With register access, the device can in turn be operated in a manual control mode, or automatic
control and reference selection mode. Hardware mode is most suitable for simple environments where minimal external
intelligence is desired. Register access provides more detailed visibility and control for references and general
synchronization operation. Stratum 3E operation requires register access to set the appropriate PLL bandwidth and to
enable phase build out.
These three main operating environments are detailed as follows:
Reset
BITS output
frequency select
0 = 2.048 MHz
1 = 1.544 MHz
Hardware Control Interfaces
Figure 13
Reset
STC3800
BITS_Sel
HM_Ref
LOS
Bus Mode:
1 = Parallel
Bmode
I/O
0 = SPI
Bus Interface
CS
ALE or SCLK
R/W or SDI
RDY or SDO
8 ^AD0-7
Interrupt
INTR
LOL
Hold_Avail
INTR
Outputs
(Optional Use)
Hardware Control – The device interfaces for hardware control are shown in Figure 13.
Reset may be pulled low for a minimum of 200nS during chip 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 may be tied input high.
For Hardware Control (no bus interface use), the device configuration data must be provided via the external EEPROM,
Dmode is tied “high”, and pump is completed automatically after any reset.
The BITS clock output frequency is selected by the BITS_Sel pin. When BITS_Sel = 1, the BITS frequency is 1.544
MHz, and when BITS_Sel = 0, the BITS frequency is 2.048 MHz.
M/S - 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 M/S to “1”.
HM_Ref - Set to “1” for hardware control of reference selection and operational mode.
Preliminary Data Sheet #: TM061 Page 40 of 48 Rev: P06 Date: 11/22/04
© Copyright 2001 The Connor-Winfield Corp. All Rights Reserved Specifications subject to change without notice