DATASHEET
LOW PHASE NOISE VCXO AND MULTIPLIER
Description
The MK2732-06 is a low-cost, low-jitter, high-performance
VCXO and PLL clock synthesizer designed to replace
expensive discrete VCXOs and multipliers. The on-chip
Voltage Controlled Crystal Oscillator (VCXO) accepts a 0 to
3 V input voltage to cause the output clocks to vary by ±100
ppm. Using IDT’s patented VCXO and analog
Phase-Locked Loop (PLL) techniques, the device uses an
inexpensive 10 MHz to 14 MHz pullable crystal input to
produce up to three output clocks.
IDT manufactures the largest variety of clocks for Set-top
boxes and Communications. Consult IDT to eliminate
VCXOs, crystals, oscillators andbuffers from your board.
MK2732-06
Features
•
•
•
•
•
•
•
Packaged in 16-pin TSSOP
Pb (lead) free package
For xDSL chipsets
For MPEG2 decoders
Replaces VCXO and multiplier
Uses an inexpensive pullable crystal
On-chip patented VCXO with pull range of 200 ppm
(±100 ppm) minimum
•
VCXO tuning voltage of 0 to 3 V
•
Zero ppm synthesis error in all clocks
•
Full CMOS output swings with 25 mA output drive
capability at TTL levels
•
Advanced, low-power, sub-micron CMOS process
•
5 V operating voltage for core, ability to run output clocks
at 3.3 V or 5 V for easy interface.
•
Available in commercial and industrial temperature
versions
Block Diagram
VDD5
VDDIO
S1, S0
2
PLL/Clock
Synthesis
Circuitry
CLK1
VIN
10 - 14 MHz X1
pullable
crystal
X2
Voltage
Controlled
Crystal
Oscillator
CLK2
REFCLK
OE (all outputs)
IDT™
LOW PHASE NOISE VCXO AND MULTIPLIER
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MK2732-06
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MK2732-06
LOW PHASE NOISE VCXO AND MULTIPLIER
VCXO AND SYNTHESIZER
Pin Assignment
X1
VDD5
VDD5
VIN
GND
GND
S1
OE
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
X2
REFCLK
NC
GND
CLK2
VDDIO
S0
CLK1
Clock Select Table
S1
S0
Input
CLK1
CLK2
REFCLK
16-pin (173 mil) TSSOP
0
0
0
M
M
M
1
1
1
0
M
1
0
M
1
0
M
1
13.248
13.248
13.248
13.248
13.5
13.5
13.5
Test mode
13.5
52.992
13.248
13.248
52.992
54
54
27
—
27
35.238
35.238
35.238
35.238
27
27
54
—
27
OFF
OFF
ON
ON
OFF
ON
ON
—
ON
0 = connect directly to ground
M=leave unconnected (floating)
1 = connect directly to VDDIO
off=output stopped low
Pin Descriptions
Pin
Number
1
2,3
4
5, 6, 13
7
8
9
10
11
12
14
15
16
Pin
Name
X1
VDD5
VIN
GND
S1
OE
CLK1
S0
VDDIO
CLK2
NC
REFCLK
X2
Pin
Type
XI
Power
VI
Power
TI
Input
Output
TI
Power
Output
—
Output
XO
Pin Description
Crystal connection. Connect to a pullable crystal of 10 to 14.318 MHz.
Core VDD. Connect to +5 V.
Voltage input to VCXO. Zero to 3 V signal which controls the frequency of the
VCXO.
Connect to ground.
Select input #1. Selects the outputs per table above. Do not exceed VDDIO.
Output Enable. Tri-states outputs when low. Do not exceed VDDIO.
Clock output #1 per table above. Amplitude = VDDIO.
Select input #0. Selects the outputs per table above. Do not exceed VDDIO.
Input and output VDD. Connect to 3.3. V or 5 V. Clock amplitude matches this
voltage.
Clock output #2 per table above. Amplitude = VDDIO.
Nothing connected internally to this pin.
Buffered crystal VCXO clock.
Crystal connection. Connect to a pullable crystal of 10 to 14 MHz.
Key: TI = tri-level input; VI = analog voltage input; XI, XO = crystal pins
IDT™
LOW PHASE NOISE VCXO AND MULTIPLIER
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LOW PHASE NOISE VCXO AND MULTIPLIER
VCXO AND SYNTHESIZER
External Component Selection
The MK2732-06 requires a minimum number of external
components for proper operation.
PCB is optional. The need for these capacitors is
determined at system prototype evaluation, and is
influenced by the particular crystal used (manufacture and
frequency) and by PCB layout. The typical required
capacitor value is 1 to 4 pF.
To determine the need for and value of the crystal
adjustment capacitors, you will need a PC board of your final
layout, a frequency counter capable of about 1 ppm
resolution and accuracy, two power supplies, and some
samples of the crystals which you plan to use in production,
along with measured initial accuracy for each crystal at the
specified crystal load capacitance, C
L
.
To determine the value of the crystal capacitors:
1. Connect VDD of the MK2732-06 to 3.3 V. Connect pin 3
of the MK2732-06 to the second power supply. Adjust the
voltage on pin 3 to 0V. Measure and record the frequency of
the CLK output.
2. Adjust the voltage on pin 3 to 3.3 V. Measure and record
the frequency of the same output.
To calculate the centering error:
Decoupling Capacitor
A decoupling capacitor of 0.01
µF
and 0.1
µF
must be
connected between VDD5 and GND on pins 2, 3 and 5, 6,
and VDDIO and GND on pins 11 and 13, as close to the
device as possible. For optimum device performance, the
decoupling capacitor should be mounted on the component
side of the PCB. Avoid the use of vias in the decoupling
circuit.
Series Termination Resistor
When the PCB trace between the clock outputs and the
loads are over 1 inch, series termination should be used. To
series terminate a 50Ω trace (a commonly used trace
impedance) place a 33Ω resistor in series with the clock line,
as close to the clock output pin as possible. The nominal
impedance of the clock output is 20Ω
.
Quartz Crystal
The MK2732-06 VCXO function consists of the external
crystal and the integrated VCXO oscillator circuit. To assure
the best system performance (frequency pull range) and
reliability, a crystal device with the recommended
parameters (as described in application note MAN05) must
be used, and the layout guidelines discussed in the following
section must be followed.
The frequency of oscillation of a quartz crystal is determined
by its “cut” and by the load capacitors connected to it. The
MK2732-06 incorporates on-chip variable load capacitors
that “pull” (change) the frequency of the crystal. The crystal
specified for use with the MK2732-06 is designed to have
zero frequency error when the total of on-chip + stray
capacitance is 14 pF.
The external crystal must be connected as close to the chip
as possible and should be on the same side of the PCB as
theMK2732-06. There should be no vias between the
crystal pins and the X1 and X2 device pins. There should be
no signal traces underneath or close to the crystal.
6
(
f
3.0V
–
f
t arg et
)
+
(
f
0V
–
f
t arg et
)
Error = 10 x ------------------------------------------------------------------------------
–
error
xtal
f
t arg et
Where:
f
target
= nominal crystal frequency
error
xtal
=actual initial accuracy (in ppm) of the crystal being
measured
If the centering error is less than ±25 ppm, no adjustment is
needed. If the centering error is more than 25 ppm negative,
the PC board has excessive stray capacitance and a new
PCB layout should be considered to reduce stray
capacitance. (Alternately, the crystal may be re-specified to
a higher load capacitance. Contact IDT for details.) If the
centering error is more than 25 ppm positive, add identical
Crystal Tuning Load Capacitors
The crystal traces should include pads for small fixed
capacitors, one between X1 and ground, and another
between X2 and ground. Stuffing of these capacitors on the
IDT™
LOW PHASE NOISE VCXO AND MULTIPLIER
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LOW PHASE NOISE VCXO AND MULTIPLIER
VCXO AND SYNTHESIZER
fixed centering capacitors from each crystal pin to ground.
The value for each of these caps (in pF) is given by:
External Capacitor =
2 x (centering error)/(trim sensitivity)
Trim sensitivity is a parameter which can be supplied by your
crystal vendor. If you do not know the value, assume it is 30
ppm/pF. After any changes, repeat the measurement to
verify that the remaining error is acceptably low (typically
less than ±25 ppm).
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK2732-06. These ratings, which are
standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at these
or any other conditions above those indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical
parameters are guaranteed only over the recommended operating temperature range.
Item
Supply Voltage, VDD
All Inputs and Outputs
Ambient Operating Temperature, Commercial version
Ambient Operating Temperature, Industrial version
Storage Temperature
Junction Temperature
Soldering Temperature
7V
Rating
-0.5 V to VDD+0.5 V
0 to +70
°
C
-40 to +85
°
C
-65 to +150
°
C
125
°
C
260
°
C
Recommended Operation Conditions
Parameter
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Reference crystal parameters
Min.
0
+4.75
Typ.
Max.
+70
+5.25
Units
°
C
V
Refer to MAN05
IDT™
LOW PHASE NOISE VCXO AND MULTIPLIER
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MK2732-06
REV H 051310
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