TRU050
Complete VCXO based Phase-Locked Loop
Features
•
Output Frequencies to 65.536 MHz
•
5.0 V or 3.3Vdc Operation
•
Tri-State Output
•
Holdover on Loss of Signal Alarm
•
VCXO with CMOS Outputs
•
0/70° or –40/85°C Temperature Range
•
Ceramic SMD Package
•
RoHS/Lead Free Compliant
The TRU050, VCXO based PLL
Description
The VI TRU050 is a user-configurable crystal-
based PLL integrated circuit. It includes a digital
phase detector, op-amp, VCXO and additional
integrated functions for use in digital
synchronization applications. Loop filter software
is available as well SPICE models for circuit
simulation.
Applications
•
Frequency Translation
•
Clock Smoothing
•
NRZ Clock Recovery
•
DSLAM, ADM, ATM, Aggregation, Optical
Switching/Routing, Base Station
•
Low Jitter PLL’s
Figure 1. TRU050 Block Diagram
Vectron International, 267 Lowell Rd, Hudson NH 03051-4916
Page 1 of 14
Tel: 1-88-VECTRON-1
•
Web:
www.vectron.com
Rev : 06Jan2006
TRU050, VCXO Based PLL
Performance Characteristics
Table 1. Electrical Performance
Parameter
Output Frequency (ordering
option)
Out 1, 5V option
Out 1, 3.3V option
Supply Voltage
1
+5
+3.3
Supply Current
Output Logic Levels
Output Logic High
2
Output Logic Low
2
Output Transition Times
Rise Time
2
Fall Time
2
Input Logic Levels
Output Logic High
2
Output Logic Low
2
Loss of Signal Indication
Output Logic High
2
Output Logic Low
2
Nominal Frequency on Loss of Signal
Output 1
Output 2
Symmetry or Duty Cycle
3
Out 1
Out 2
RCLK
Absolute Pull Range,
ordering option
o
ver operating temp, aging, power supply
variations
Symbol
Min
1.000
1.000
Typical
Maximum
65.636
51.840
Units
MHz
MHz
V
V
mA
V
V
ns
ns
V
V
V
V
ppm
ppm
%
%
%
ppm
V
DD
4.5
3.0
I
DD
V
OH
V
OL
t
R
t
F
V
IH
V
IL
V
OH
V
OL
2.0
0.5
2.5
0.5
±75
±75
SYM1
SYM2
RCLK
APR
40/60
45/55
40/60
±50
±80
±100
0.5
0.3
Positive
0.53
0.35
0/70 or –40/85
I
VCXO
±1
rad/V
rad/V
°C
uA
2.5
0.5
5
5
5.0
3.3
5.5
3.6
65
Test Conditions for APR (+5V option)
Test Conditions for APR (+3.3V option)
Gain Transfer
Phase Detector Gain
+5V option
+3.3V Option
Operating temperature,
ordering option
Control Voltage Leakage Current
V
C
V
C
4.5
3.0
V
V
1. A good quality 0.01uF in parrallel with a 0.1 uf capacitor should be located as close to pin 16 to ground as possible.
2. Figure 1 defines these parameters. Figure 2 illustrates the equivalent five-gate TTL load and operating conditions under which
these parameters are tested and specified. Loads greater than 15 pF will adversely effect rise/fall time and duty cycle.
3. Symmetry is defined as (ON TIME/PERIOD with Vs=-1.4 V for both 5V and 3.3V operation.
T
R
80
%
T
F
I
DD
16
V
DD
+
-
650Ω
1.4V
20
%
.
1µF
.01µF
I
C
V
C
1
+
-
3
15pF
1.8k
On Time
Period
Figure 2. Output Waveform
Figure 3. OUT1, OUT2, RDATA and RCLK
Test Conditions (25±5°C)
Tel: 1-88-VECTRON-1
•
Web:
www.vectron.com
Rev : 06Jan2006
Vectron International, 267 Lowell Rd, Hudson NH 03051-4916
Page 2 of 14
TRU050, VCXO Based PLL
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings can permanently damage the device. Functional
operation is not implied at these or any other conditions in excess of conditions represented in the
operational sections of this data sheet. Exposure to absolute maximum ratings for extended periods may
adversely affect device reliability.
Table 2. Absolute Maximum Ratings
Parameter
Power Supply
Storage Temperature
Soldering Temperature/Duration
Clock and Data Input Range
Symbol
V
DD
Tstorage
T
PEAK
/ t
P
CLKIN, DATAIN
Ratings
7
-55/125
260 / 40
Gnd-0.5 to V
DD
+0.5
Unit
Vdc
°C
°C/sec
V
Reliability
The TRU050 is capable of meeting the following qualification tests.
Table 3. Environmental Compliance
Parameter
Mechanical Shock
Mechanical Vibration
Solderability
Gross and Fine Leak
Resistance to Solvents
Conditions
MIL-STD-883, Method 2002
MIL-STD-883, Method 2007
MIL-STD-883, Method 2003
MIL-STD-883, Method 1014, 100% Tested
MIL-STD-883, Method 2016
Handling Precautions
Although ESD protection circuitry has been designed into the the TRU050, proper precautions should be
taken when handling and mounting. VI employs a human body model and a charged-device model
(CDM) for ESD susceptibility testing and design protection evaluation. ESD thresholds are dependent on
the circuit parameters used to define the model.
Table 4. ESD Ratings
Model
Human Body Model
Charged Device Model
Minimum
1500V
1000V
MIL-STD 3015
JESD 22-C101
Vectron International, 267 Lowell Rd, Hudson NH 03051-4916
Page 3 of 14
Tel: 1-88-VECTRON-1
•
Web:
www.vectron.com
Rev : 06Jan2006
TRU050, VCXO Based PLL
TRU050 Theory of Operation
Phase Detector
The phase detector has two buffered inputs, DATAIN and CLKIN, which are designed to switch at 1.4
volts. DATAIN is designed to accept an NRZ data stream but may also be used for clock signals which
have about a 50% duty cycle. CLKIN is connected to OUT1 or OUT2, or a divided version of one of these
outputs. CLKIN and DATAIN and are protected by ESD diodes and should not exceed the power supply
voltage or ground by more than a few hundred millivolts.
The phase detector is basically a latched flip flop/exclusive-or gate/differential amplifier filter design to
produce a DC signal proportional to the phase between the CLKIN and DATAIN signals, see figure 4 for a
block diagram and figure 5 for a open loop transfer curve. This simplies the PLL design as the designer
does not have to filter narrow pulse signal to a DC level. Under locked conditions the rising edge CLKIN
will be centered in the middle of the DATAIN signal, see figure 6.
The phase detector gain is 0.53V/rad x data density for 5volt operation, and 0.35V/rad x data density for
3.3 volt operation. Data density = 1.0 for clock signals and is system dependent on coding and design
for NRZ signals, but 0.25 could be used as a starting point for data density.
The phase detector output is a DC signal for DATAIN frequencies greater than 1MHz but produces
signficant ripple when inputs are less than 200kHz. Additional filtering is required for low input frequency
applications such as 8kHz frequency translation, see figures 8 and 9.
Under closed loop conditions the active filter has a blocking capacitor which provides a very high DC
gain, so under normal locked conditions and input frequencies >1MHz, PHO will be about V
DD
/2 and will
not vary signifigantly with changes in input frequency (within lock range). The control (voltage pin 1) will
vary according to the input frequency offset, but PHO will remain relatively constant.
Data In
(pin 7)
D
Clock In
(pin 9)
Q
1
30 kΩ
20 kΩ
D
Q
2
PHO
(pin 6)
Gain = 5 V / 2π
Gain = 2 / 3
Figure 4. Simplified Phase Detector Block Diagram
Vectron International, 267 Lowell Rd, Hudson NH 03051-4916
Page 4 of 14
Tel: 1-88-VECTRON-1
•
Web:
www.vectron.com
Rev : 06Jan2006
TRU050, VCXO Based PLL
V
DD
−π
V
d
V
DD
/2
0
+π
Relative
Phase (θ
e
)
0V
Gain Slope = V
DD
/ 2π
Figure 5. Open Loop Phase Detector Transfer Curve
Recovered Clock and Data Alignment Outputs
The TRU050 is designed to recover an imbedded clock from an NRZ data signal and retime it with a data
pattern. In this application, the VCXO frequency is exactly the same frequency as the NRZ data rate and
the outputs are taken off Pin 11, RCLK, and Pin 12, RDATA. Under locked conditions, the falling edge of
RCLK is centered in the RDATA pattern. Also, there is a 1.5 clock cyle delay between DATAIN and
RDATA. Figure 6 shows the relationship between the DATAIN, CLKIN, RDATA and RCLK.
Data In
Data1
Clock In
Recovered
Data
Recovered Clock
Data1
Figure 6. Clock and Data Timing Relationships for the NRZ data
Other RZ encoding schemes such as Manchester or AMI can be accomidated by using a TRU050 at
twice the baud rate.
Loss of Signal, LOS and LOSIN
The LOS circuit provides an output alarm flag when the DATAIN input signal is lost. The LOS output is
normally a logic low and is set to a logic high after 256 consecutive clock periods on CLKIN with no
detected DATAIN transitions. This signal can be used to either flag external alarm circuits and/or drive the
TRU050’s LOSIN input. When LOSIN is set to a logic high, the VCXO control voltage (pin 1) is switched
to an internal voltage which centers OUT1 and OUT2 to center frequency +/-75ppm. Also, LOS
automatically closes the op amp feedback which means the op-amp is a unity gain buffer and will
produce a DC voltage equal to the +op amp voltage (pin 4), usually VDD/2.
Vectron International, 267 Lowell Rd, Hudson NH 03051-4916
Page 5 of 14
Tel: 1-88-VECTRON-1
•
Web:
www.vectron.com
Rev : 06Jan2006
Analog electronics
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