IDT82V2108PXG IDT, Integrated Device Technology Inc, IDT82V2108PXG Datasheet - Page 96

• Manufacturer Part Number: IDT82V2108PXG
• Description: IC FRAMER T1/J1/E1 8CH 128-PQFP
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT82V2108PXG

• Controller Type: T1/E1/J1 Framer
• Interface: Parallel
• Voltage - Supply: 2.97 V ~ 3.63 V
• Current - Supply: 160mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 128-MQFP, 128-PQFP
• Screening Level: Industrial
• Mounting: Surface Mount
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 82V2108PXG

IDT82V2108
3.19.2
path and the transmit path.
clock output from the jitter attenuator is generated by adaptively dividing
the 37.056 MHz XCK according to the phase difference between the
output smoothed clock and the input reference clock. The ratio between
the frequency of the input reference clock and the frequency applied to
the phase discriminator input is equal to the (N1 + 1) (the N1 is in b7~0,
T1/J1-011H for receive path and in b7~0, T1/J1-019H for transmit path).
The ratio between the frequency of the output smoothed clock and the
frequency applied to the phase discriminator input is equal to the (N2 +
1) (the N2 is in b7~0, T1/J1-012H for receive path and in b7~0, T1/J1-
01AH for transmit path). The phase fluctuations of the input reference
clock are attenuated by dividing the input reference clock and output
smoothed clock by the (N1 + 1) and the (N2 + 1) respectively in the
DPLL so that the frequency of the output smoothed clock is equal to the
average frequency of the input reference clock. The phase fluctuations
with a jitter frequency above 6.6 Hz are attenuated by 6 dB per octave
when the N1 (b7~0, T1/J1-011H for receive path and b7~0, T1/J1-019H
for transmit path) and the N2 (b7~0, T1/J1-012H for receive path and
b7~0, T1/J1-01AH for transmit path) are in their default value. It will
change when the N1 and the N2 are changed. Generally, when the N1
and the N2 increase, the curves of the Jitter Tolerance and Jitter Trans-
fer in the graph will left-shift and When N1 and N2 decrease, they will
right-shift. The phase fluctuations (wander) with frequency below 6.6 Hz
are tracked by the output smoothed clock. The output smoothed clock is
used to clock the data out of the FIFO.
the FIFO is already full, overflow will occur and the OVRI (b1, T1/J1-
010H for receive path and b1, T1/J1-018H for transmit path) will indi-
cate. If data is still read from the FIFO when the FIFO is already empty,
underrun will occur and the UNDI (b0, T1/J1-010H for receive path and
b0, T1/J1-018H for transmit path) will indicate. Thus, if the OVRE (b2,
T1/J1-013H for receive path and b2, T1/J1-01BH for transmit path) and
the UNDE (b3, T1/J1-013H for receive path and b3, T1/J1-01BH for
transmit path) are set respectively, the interrupts on the INT pin may
occur. The jitter attenuation can be limited by setting the LIMIT (b0, T1/
J1-013H for receive path and b0, T1/J1-01BH for transmit path) to keep
the FIFO 1 UI away from being full or empty,. Thus, the DPLL will track
the jitter of the input reference clock by increasing or decreasing the fre-
quency of the output smoothed clock to prevent the FIFO being empty or
full. The FIFO can also self-center its read pointer by setting the CENT
(b4, T1/J1-013H for receive path and b4, T1/J1-01BH for transmit path).
The FIFO can be set to be bypassed by the FIFOBYP (b7, T1/J1-000H
for receive path and b7, T1/J1-004H for transmit path).
bypassed.
3.19.2.1
jitter attenuation while generating minimal residual jitter. It can accom-
modate up to 45 UI of input jitter at jitter frequencies above 12 Hz. For jit-
ter frequencies below 9 Hz, which can be correctly called wander, the
Functional Description
Two Jitter Attenuators are provided independently in the receive
The Jitter Attenuator integrates a FIFO and a DPLL. The smoothed
The FIFO is 48 bits deep. If data is still written into the FIFO when
However, in the Transmit Clock Master mode, the TJAT should be
Each Jitter Attenuator block provides excellent jitter tolerance and
T1/J1 MODE
Jitter Characteristics
86
tolerance increases 20 dB per decade. In most applications the each Jit-
ter Attenuator block will limit jitter tolerance at lower jitter frequencies
only. For high frequency jitter, above 10 kHz for example, other factors
such as clock and data recovery circuitry may limit jitter tolerance and
must be considered. For low frequency wander, below 10 Hz for exam-
ple, other factors such as slip buffer hysteresis may limit wander toler-
ance and must be considered. The Jitter Attenuator blocks meet the low
frequency jitter tolerance requirements AT&T TR 62411 for T1.
cies below 7 Hz, and attenuates jitter at frequencies above 7 Hz by 20
dB per decade. In most applications the Jitter Attenuator blocks will
determine jitter attenuation for higher jitter frequencies only. Wander,
below 10 Hz for example, will essentially be passed unattenuated
through DJAT. Jitter, above 10 Hz for example, will be attenuated as
specified, however, outgoing jitter may be dominated by the generated
residual jitter in cases where incoming jitter is insignificant. This gener-
ated residual jitter is directly related to the use of 24X (37.056 MHz) dig-
ital phase locked loop for transmit clock generation.
TR 62411. The block allows to meet the implied jitter attenuation require-
ments for a TE or NT1 given in ANSI Standard T1.408, and the implied
jitter attenuation requirements for a type II customer interface given in
ANSI T1.403.
3.19.2.2
frequency that a device can accept without exceeding its linear operat-
ing range, or corrupting data. For the Jitter Attenuator, the input jitter tol-
erance is 48 UIpp with no frequency offset. The frequency offset is the
difference between the frequency of XCK divided by 24 and that of the
input reference clock.
3.19.2.3
0.1 dB greater than the input jitter. Jitter frequencies above 7 Hz are
attenuated at a level of 6 dB per octave, as shown in Figure - 66.
3.19.2.4
overrunning or under running, the tracking range is 1.48 to 1.608 MHz.
The guaranteed linear operating range is 1.544 MHz ± 963 Hz (for T1)
with no jitter or XCK frequency offset.
The Jitter Attenuator exhibits negligible jitter gain for jitter frequen-
The Jitter Attenuator meets the jitter transfer requirements of AT&T
Jitter tolerance is the maximum input phase jitter at a given jitter
Refer to Figure - 65 for the Jitter Tolerance.
The output jitter for jitter frequencies from 0 to 7 Hz is no more than
In the non-attenuating mode, that is, when the FIFO is within 1 UI of
Jitter Tolerance
Jitter Transfer
Frequency Range
T1 / E1 / J1 OCTAL FRAMER
March 5, 2009