SY87721LHI Micrel Inc, SY87721LHI Datasheet - Page 7

• Manufacturer Part Number: SY87721LHI
• Description: IC CLOCK/DATA RECOVERY 64-TQFP
• Manufacturer: Micrel Inc
• Type: Clock and Data Recovery (CDR)r

Specifications of SY87721LHI

• Input: Differential
• Output: Differential
• Frequency - Max: 340MHz
• Voltage - Supply: 3.15 V ~ 3.45 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-TQFP Exposed Pad, 64-eTQFP, 64-HTQFP, 64-VQFP
• Frequency-max: 340MHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Micrel, Inc.
General
circuit, capable of handling NRZ data rates from 28MHz
through to 2.7GHz. A reference PLL is used as a frequency
synthesizer, both to multiply a reference clock to the desired
transmit rate, and to train the recovery PLL in preparation
for actual data recovery.
Link Fault Algorithm
This circuit provides the following functions: Under Loss-of-
Lock (LOL) conditions, which can occur when the Carrier
Detect (CD) input is active HIGH, the output of the RCLK
approximates the output of the TCLK, within a lock range
as specified by the state of ALRSEL.
the Carrier Detect (CD) input to inactive logic LOW, the
output of the RCLK becomes an exact copy of the TCLK
output. This is the result of forcing the recovery PLL to lock
to the synthesized reference.
inactive logic LOW.
recover the clock of the incoming data stream. This
procedure is triggered either by a falling edge on CD, or by
the recovered clock PLL indicating a frequency error,
compared to the synthesized reference, of greater than
500ppm or 4,500ppm, as selected by ALRSEL. With the
CD input set active HIGH, the algorithm begins by phase
and frequency training the recovery PLL to the synthesized
Notes:
1. REFCLK multiplier of 1 or 2 is not allowed in this range.
2. REFCLK multiplier of 1 is not allowed in this range.
3. Combinations of VCOSEL and FREQSEL other then those in this table result in undefined behavior, and should not be used.
M9999-012508
[e-mail] or [phone]
DESCRIPTION
The SY87721L is a complete clock and data recovery
The SY87721L includes a Link Fault Detection circuit.
Under Loss-of-Signal (LOS) conditions, enabled by driving
Under LOL and LOS conditions, the LFIN output is an
SY87721L follows a prescribed procedure, to acquire and
VCOSEL1
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
VCOSEL2
0
0
0
0
0
1
0
1
1
1
1
1
1
1
1
Table 3
(3)
FREQSEL1
. Frequency Range Selection Truth Table
0
0
0
1
1
0
0
0
0
0
0
1
1
1
1
7
reference. Once the recovery PLL is within the specified
lock range, determined by the state of ALRSEL, the
SY87721L will switch from a phase-frequency comparison
with the synthesized reference, to a phase-only comparison
with the incoming data stream. When the recovery PLL is
locked to this incoming data stream (that is, after phase
step recovery), then data recovery may proceed and LFIN
asserts. Once locked and accepting data, the LFIN signal
may de-assert should the data input frequency deviate too
far from the synthesized reference frequency.
VCO Selection
on the application and the frequency range, any one of
these four perform data recovery.
general purpose VCOs each covering one of three frequency
ranges. However, to extend the range of the device, the
output of the VCO may be divided down.
VCOs (VCOSEL = 1, 0 or 0,1 ), this divisor is always set to
1. For the lowest frequency VCO, the FREQSEL pins select
which divisor, and hence, which range of frequencies the
VCO will work over.
narrow band, extremely low jitter PLL. It also uses the
FREQSEL divisor to choose the correct SONET/SDH
frequency.
FREQSEL2
SY87721L sports four complete VCO circuits. Depending
As indicated by the VCO selection table, there are three
In the case of the two highest frequency general purpose
In addition, for SONET/SDH applications, there is a
The valid modes of operation are shown in Table 3.
0
0
1
0
1
0
0
0
0
1
1
0
0
1
1
FREQSEL3
0
1
0
0
0
0
0
0
1
0
1
0
1
0
1
2488 (OC48)–2700
622 (OC12)–675
155 (OC3)–168
Range (MHz)
650–1300
1800–2700
1250–1800
325–650
1244-1350
311–337
163–325
109–216
82–162
55–108
41–81
28–54
(2)
(1)
SY87721L