CS61310 Cirrus Logic, Inc., CS61310 Datasheet - Page 10

• Manufacturer Part Number: CS61310
• Description: Long Haul T1 Line Interface Unit
• Manufacturer: Cirrus Logic, Inc.

2.4.3
The receiver jitter tolerance is shown in Figure 7.
The CS61310 jitter tolerance exceeds AT&T
62411 for synchronizers.
2.5
Jitter attenuation can be implemented in either the
transmit (JASEL low) or receive (JASEL high)
paths, or it can be eliminated from the circuit by
setting the XTALIN pin high. The jitter attenuator
on the CS61310 does not require a crystal. It is ac-
tivated when XTALIN is either connected to
ground or left open; connecting to ground is the
preferred method.
The jitter attenuator corner frequency is set at 4 Hz,
with attenuation increasing at a 20 dB per decade
rate above 4 Hz. A typical jitter attenuation graph
is shown in Figure 9.
10
PEAK-TO-PEAK
Figure 7. Minimum Input Jitter Tolerance of Receiver
(unit intervals)
JITTER
RCLK
LATN
Jitter Attenuator
Jitter Tolerance
300
138
100
28
10
.4
.1
1
1
AT&T 62411
10
1
JITTER FREQUENCY
Minimum
Performance
100
LATN = 1 RCLK, 7.5 dB of Attenuation
300
2
700
LATN = 2 RCLK, 15 dB of Attenuation
1k
Figure 8. LATN Pulse Width encoding
3
(Hz)
10k
LATN = 3 RCLK, 22.5 dB of Attenuation
4
100k
LATN = 4 RCLK, 0 dB of Attenuation
5
2.6
The LATN pin outputs a coded signal that repre-
sents the signal level at the input of the receiver. As
shown in Figure 8, the LATN output is measured
against RCLK to provide the signal level in 7.5 dB
increments. In host mode, the receive input signal
level can be read from the Equalizer Gain register,
address 0x12, to greater resolution, dividing the in-
put range into 20 steps of 2 dB increments.
2.7
The receiver will indicate loss of signal by setting
the LOS pin high in hardware mode (CR1.0 = 1 in
host mode). LOS is active on power up, reset, when
receiver gain is maximized, upon receiving 175+/-
15 consecutive zeros, or when the received signal
power falls below below the signal level, “Loss of
Signal Threshold” listed under Analog Specifica-
tions. Received zeros are counted based on recov-
ered clock cycles. While in the LOS state, received
Figure 9. Typical Jitter Transfer Function
Receiver Line Attenuation Indication
Receiver Loss of Signal
10
20
30
40
50
60
0
1
Maximum
Attenuation
Limit
10
Minimum Attenuation Limit
Frequency in Hz
100
62411 Requirements
Measured Performance
1 k
CS61310
10 k
DS440PP2