MT9045AN Zarlink Semiconductor, Inc., MT9045AN Datasheet - Page 5

• Manufacturer Part Number: MT9045AN
• Description: Framer, Framer Circuit, T1/E1/OC3 System Synchronizer
• Manufacturer: Zarlink Semiconductor, Inc.

Data Sheet
Corrector Circuit. The selection is based on the Control, Mode and Reference Selection of the device. See
Table 1 and Table 4.
Frequency Select MUX Circuit
The MT9045 operates with one of four possible input reference frequencies (8kHz, 1.544MHz, 2.048MHz or
19.44MHz). The frequency select inputs (FS1 and FS2) determine which of the four frequencies may be used
at the reference inputs (PRI and SEC). Both inputs must have the same frequency applied to them. A reset
(RST) must be performed after every frequency select input change. See Table 1.
Time Interval Error (TIE) Corrector Circuit
The TIE corrector circuit, when enabled, prevents a step change in phase on the input reference signals (PRI or
SEC) from causing a step change in phase at the input of the DPLL block of Figure 1.
During reference input rearrangement, such as during a switch from the primary reference (PRI) to the
secondary reference (SEC), a step change in phase on the input signals will occur. A phase step at the input of
the DPLL would lead to unacceptable phase changes in the output signal.
As shown in Figure 3, the TIE Corrector Circuit receives one of the two reference (PRI or SEC) signals, passes
the signal through a programmable delay line, and uses this delayed signal as an internal virtual reference,
which is input to the DPLL. Therefore, the virtual reference is a delayed version of the selected reference.
PRI or SEC
Select Mux
Reference
from
0
1
Programmable
Delay Circuit
FS2
0
1
Table 1 - Input Frequency Selection
Figure 3 - TIE Correction Circuit
FS1
0
1
0
1
Zarlink Semiconductor Inc.
State Machine
TIE Corrector
Enable
Control
from
Circuit
TCLR
Input Frequency
Resets Delay
19.44MHz
1.544MHz
2.048MHz
Delay Value
8kHz
Control Signal
Select MUX
Signal from
Compare
Frequency
Feedback
Circuit
Reference
to DPLL
Virtual
MT9045
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