ADN2819ACPZ-CML-RL Analog Devices Inc, ADN2819ACPZ-CML-RL Datasheet - Page 14

• Manufacturer Part Number: ADN2819ACPZ-CML-RL
• Description: IC,Clock/Data Recovery,LLCC,48PIN,CERAMIC
• Manufacturer: Analog Devices Inc
• Type: Clock and Data Recovery (CDR)r

Specifications of ADN2819ACPZ-CML-RL

• Output: CML
• Frequency - Max: 2.7GHz
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LFCSP
• Frequency-max: 2.7GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Input: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ADN2819
FUNCTIONAL DESCRIPTION
MULTIRATE CLOCK AND DATA RECOVERY
The ADN2819 will recover clock and data from serial bit
streams at OC-3, OC-12, OC-48, and GbE data rates as well as
the 15/14 FEC rates. The output of the 2.5 GHz VCO is divided
down in order to support the lower data rates. The data rate is
selected by the SEL[2..0] inputs (see Table 5).
Table 5. Data Rate Selection
SEL[2..0]
000
001
010
011
100
101
110
111
LIMITING AMPLIFIER
The limiting amplifier has differential inputs (PIN/NIN) that
are internally terminated with 50 Ω to an on-chip voltage
reference (VREF = 0.6 V typically). These inputs are normally
ac-coupled, although dc-coupling is possible as long as the input
common-mode voltage remains above 0.4 V (see Figure 26,
Figure 27, and Figure 28 in the Applications Information
section). Input offset is factory trimmed to achieve better than
4 mV typical sensitivity with minimal drift. The limiting
amplifier can be driven differentially or single-ended.
SLICE ADJUST
The quantizer slicing level can be offset by ±100 mV to mitigate
the effect of amplified spontaneous emission (ASE) noise by
applying a differential voltage input of ±0.8 V to SLICEP/N
inputs. If no adjustment of the slice level is needed, SLICEP/N
should be tied to VCC.
LOSS OF SIGNAL (LOS) DETECTOR
The receiver front end level signal detect circuit indicates when
the input signal level has fallen below a user adjustable
threshold. The threshold is set with a single external resistor
from Pin 1, THRADJ, to GND. The LOS comparator trip point
versus the resistor value is illustrated in Figure 4 (this is only
valid for SLICEP = SLICEN = VCC). If the input level to the
ADN2819 drops below the programmed LOS threshold,
SDOUT (Pin 45) will indicate the loss of signal condition with a
Logic 1. The LOS response time is ~300 ns by design, but it is
dominated by the RC time constant in ac-coupled applications.
If the LOS detector is used, the quantizer slice adjust pins must
both be tied to VCC. This is to avoid interaction with the LOS
threshold level.
Rate
OC-48
GbE
OC-12
OC-3
OC-48 FEC
GbE FEC
OC-12 FEC
OC-3 FEC
Frequency (MHz)
2488.32
1250.00
622.08
155.52
2666.06
1339.29
666.51
166.63
Rev. B | Page 14 of 24
Note that it is not expected to use both LOS and slice adjust at
the same time. Systems with optical amplifiers need the slice
adjust to evade ASE. However, a loss of signal in an optical link
that uses optical amplifiers causes the optical amplifier output
to be full-scale noise. Under this condition, the LOS would not
detect the failure. In this case, the loss of lock signal indicates
the failure because the CDR circuitry is unable to lock onto a
signal that is full-scale noise.
REFERENCE CLOCK
There are three options for providing the reference frequency to
the ADN2819: differential clock, single-ended clock, or crystal
oscillator. See Figure 17, Figure 18, and Figure 19 for example
configurations.
OSC
VCC
CLK
Figure 18. Single-Ended REFCLK Configuration
Figure 17. Differential REFCLK Configuration
OUT
VCC
VCC
VCC
VCC
VCC
VCC
REFCLKN
NC
REFCLKP
REFCLKP
REFCLKN
XO1
XO2
XO1
XO2
REFSEL
REFSEL
ADN2819
ADN2819
100kΩ
100kΩ
OSCILLATOR
OSCILLATOR
CRYSTAL
CRYSTAL
100kΩ
100kΩ
BUFFER
BUFFER
VCC/2
VCC/2