PXB4221EV34GXP Lantiq, PXB4221EV34GXP Datasheet - Page 66

• Manufacturer Part Number: PXB4221EV34GXP
• Manufacturer: Lantiq

Specifications of PXB4221EV34GXP

• Data Rate: 2.048Mbps
• Number Of Channels: 1
• Operating Supply Voltage (typ): 3.3V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

Figure 17
If the first cell has maximum negative CDV there will be “starv_ini” + 1 octets left in the
Reassembly Buffer when the following cell arrives with maximum negative CDV. In case
the following cell arrives with maximum positive CDV it will be “starv_ini” + 1 plus the
amount of data to be transmitted in the expectation interval. Just after cell arrival the
filling level of the Reassembly Buffer is at its maximum:
The delay introduced by the Reassembly Buffer is:
Structured Data Transfer:
After activation of a channel both SAR Receiver and Framer Transmit Interface start
operation. As long as no reassembled cell in P format is accepted the Reassembly Buffer
it is considered to be in underflow condition and starvation octets are passed to the
Framer Transmit Interface.
After that, “starv_ini” + 1 starvation octets are given to the Framer Transmit Interface.
Then, the transmitter reads as many octets from the Reassembly Buffer as indicated by
the pointer field. For each octet one starvation octet is given to the Framer Transmit
Interface. The next octet to be read from the Reassembly Buffer is the “ATM Start of
Structure” (The octet where the AAL1 pointer field points at).
Data Sheet
Framer
delay
4
0
Interf.
bufflsize partfill
Filling Level [octets]
Reassembly Buffer
buff_lsize
=
Starvation octets
Data octets
starvini 125 s
----------------------------------------- -
T
0
Reassembly Buffer Initialization: Negative CDV at Start Up
N
T
0
+CDV
T
+
0
+CDV+T
starvini
T
T
T: Average cell distance
0
S
: First cell arrival time (theoretical)
: (starv_ini + 1) * 125µs / N
S
+ +
1
T
T
0
0
+T-CDV
+T
Example: part_fill = 16 octets; N = 16
1st cell has max. neg. CDV = 15,625µs
2nd cell has max. pos. CDV = -15,625µs
=
partfill
66
PXB 4219E, PXB 4220E, PXB 4221E
+
4
CDV
T
Operational Description
0
+2*T
-------------- -
125 s
N
T
0
Reassembly Buffer neg CDV
+2*T+CDV
IWE8, V3.4
2003-01-20
Time
Time
[6]
[7]