PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 87

• Manufacturer Part Number: PEF2091
• Description: ICs for Communications(ISDN Echocancellation Circuit)
• Manufacturer: Siemens Semiconductor Group

Note 19: It may be necessary to use a multiplexer for the PLL-reference clock because
XIN/XOUT
A free running crystal or other clock source should provide a 15.36-MHz base clock (see
also "External Circuitry", page 249 for more informations about crystal properties).
CLS
A 512 kHz clock synchronous to the PTT is provided. This clock should be used as the
reference clock for the PLL. It is not available in power down.
3.7.4
Figure 35
In repeater applications the NT repeater issues IOM
repeater. The LT repeater is synchronized to the upstream unit through the NT repeater.
To achieve this, a PLL is required to provide a synchronized 15.36 MHz master clock to
the LT repeater.
Semiconductor Group
Interface
the CLS-signal is available only if the corresponding line is active. If the
referenced line is not active the PLL must be supplied by the CLS of another
active IEC-Q of the PBX.
U
Repeater Modes
Clock Generation in Repeater Mode
(Downstream)
XIN
LT-RP
Synchr.
15.36 MHz
CLS
512 KHz
DCL
PLL
FSC
87
DCL
15.36 MHz
CLS
®
-2 clocks for direct use in the LT
(Downstream)
NT-RP
XIN XOUT
Synchr.
Functional Description
Interface
Data Sheet 01.99
U
PEB 2091
PEF 2091