MT9042CP1 Zarlink Semiconductor, Inc., MT9042CP1 Datasheet - Page 16

• Manufacturer Part Number: MT9042CP1
• Description: PLL, Dual Reference Frequency Selectable Digital PLL with Multiple Clock Outputs
• Manufacturer: Zarlink Semiconductor, Inc.

MT9042C
When 10 Normal to Holdover to Normal mode
change sequences occur without MTIE enabled, and
in each case holdover was entered for 2s, each
mode change sequence could still account for a
phase change as large as 350ns. However, there
would be no accumulated phase change, since the
input to output phase is re-aligned after every
Holdover to Normal state change. The overall MTIE
would only be 350ns.
Reset Circuit
A simple power up reset circuit with about a 50us
reset low time is shown in Figure 15. Resistor R
for protection only and limits current into the RST pin
during power down conditions. The reset low time is
not critical but should be greater than 300ns.
16
To Line 1
To Line 2
TX Line
TX Line
RX Line
RX Line
XFMR
XFMR
XFMR
XFMR
Figure 14 - Dual T1 Reference Sources with MT9042C in 1.544MHz Automatic Control
To
To
To
To
TTIP
TRING
RTIP
RRING
TTIP
TRING
RTIP
RRING
MT9074
MT9074
MT8985
E1.5o
E1.5o
DSTo
DSTo
DSTi
DSTi
STo0
STo1
STi0
STi1
LOS
LOS
C4i
C4i
C4i
F0i
F0i
F0i
P
is
+ 5V
1kΩ
MT9042C
10nF
10kΩ
SEC
Figure 15 - Power-Up Reset Circuit
TRST
RST
PRI
LOS1
LOS2
MS1
MS2
RSEL
MT9042C
RST
OSCi
+ 5V
C4o
C2o
FS1
FS2
GTo
F0o
GTi
+ 5V
1kΩ
R
10kΩ
Out
P
150kΩ
20MHz
R
1kΩ
1kΩ
CLOCK
+5V
±
32ppm
10uF
10nF
C
+