LTC2272CUJ LINER [Linear Technology], LTC2272CUJ Datasheet - Page 28

• Manufacturer Part Number: LTC2272CUJ
• Description: 16-Bit, 80Msps/65Msps Serial Output ADC
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
Initial Frame Synchronization
In the absence of a frame clock, it is necessary to deter-
mine the start of each frame through a synchronization
process. To establish frame synchronization, Figures 14
and 15 illustrate the following sequence:
• The receiver issues a synchronization request via the
• If the synchronization request is active for more than
LTC2273/LTC2272
28
synchronization interface.
one ENC clock cycle, the LTC2273/LTC2272 will transmit
a synchronization preamble. When the ISMODE pin is
low the transmitted preamble will consist of consecu-
tive K28.5 comma symbols in conformance with the
JESD204 specifi cation. When the ISMODE pin is high,
a series of idle ordered sets will be transmitted. The
idle ordered sets consist of a K28.5 comma followed by
either D5.6 or D16.2 as defi ned in IEEE Std 802.3-2002
part3, Clause 36.2.4.12.
SERIAL DATA OUT
PARALLEL DATA
ANALOG INPUT
8B/10B DATA
INTERNAL
INTERNAL
ENC
+
N – 6
N – 9
Figure 13. Timing Relationship of Analog Sample to Serial Data Out
N – 10
t
BIT
N
t
H
t
AP
t
CONV
N – 5
N – 8
N – 9
t
L
N + 1
N – 4
N – 7
• The receiver searches for the expected preamble and
• The receiver deactivates the synchronization request.
• Upon detecting the deactivation of the synchronization
• At the start of the next frame, the LTC2273/LTC2272
• The receiver designates the fi rst data character received
N – 8
LAT
waits for the correct reception of an adequate number
of preamble characters.
request, the LTC2273/LTC2272 continue to transmit the
synchronization preamble until the end of the frame.
will begin transmitting data characters.
after the preamble transmission to be the start of the
frame. The fi rst octet of the frame contains the most
signifi cant byte of the ADC’s output word.
P
N + 2
N + 8
N + 3
N
N – 1
N + 9
N + 4
N + 1
N
22732 F13
N + 10
22732f