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MK3724
VCXO PLUS AUDIO CLOCK FOR STB
Description
The MK3724 is a low cost, low jitter, high performance VCXO and PLL clock synthesizer designed to replace expensive discrete VCXOs and multipliers. The patented on-chip Voltage Controlled Crystal Oscillator accepts a 0 to 3.3 V input voltage to cause the output clocks to vary by 115 ppm. Using ICS' analog/digital Phase-Locked Loop (PLL) techniques, the device uses an inexpensive 27 MHz pullable crystal input to produce a reference output and a selectable audio clock. ICS manufactures the largest variety of VCXO based timing devices for all applications. Consult ICS to eliminate VCXOs, crystals, and oscillators from your board. The frequency of the on-chip VCXO is adjusted by an external control voltage connected to VIN. Because VIN is a high impedance input, it can be driven directly from an PWM RC integrator circuit.
Features
* * * * * * * * * * *
Packaged in 16-pin TSSOP Available in Pb free packaging Replaces a VCXO and oscillator Operating voltage of 3.3 V Provides output of 27 MHz plus audio clock Uses an inexpensive 27 MHz pullable crystal On-chip patented VCXO with pull range of 230 ppm (minimum) VCXO tuning voltage of 0 to 3.3 V Advanced, low power, sub-micron CMOS process Industrial temperature range available For other standard audio frequencies see the MK3722
Block Diagram
VDD
3
S2:S0 VIN X1 27 MHz Pullable Crystal
3
PLL/Clock Synthesis Circuitry
ACLK
X2
Voltage Controlled Crystal Oscillator
3
27MHz
GND
PDTS
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525 Race Stre et, San Jo se, CA 9 5126
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MK3724 VCXO PLUS AUDIO CLOCK FOR STB
Pin Assignment
X2 X1 VDD VDD VIN GND GND PDTS 1 2 3 4 5 6 7 8 16-pin TSSOP 16 15 14 13 12 11 10 9 S1 NC VDD S0 27M GND ACLK S2
Audio Clock Select Table
S2
0 0 0 0 1 1 1 1
S1
0 0 1 1 0 0 1 1
S0
0 1 0 1 0 1 0 1
ACLK (MHz)
3.072 4.096 6.144 8.192 12.288 24.576 33.8688 73.728
Pin Descriptions
Pin Number
1 2 3 4 5 6 7 8 9 10 11 12 13
Pin Name
X2 X1 VDD VDD VIN GND GND PDTS S2 ACLK GND 27M S0
Pin Type
Output Input Power Power Input Power Power Power Input Output Power Output Input
Pin Description
Crystal connection. Connect to a 27 MHz fundamental mode pullable crystal. Crystal connection. Connect to a 27 MHz fundamental mode pullable crystal. Connect to +3.3 V. Connect to +3.3 V. Voltage input to VCXO. Changing the voltage between 0 to 3.3 V controls the VCXO frequency. Connect to ground. Connect to ground. Power Down Tri-state. This pin powers down entire chip and tri-states the outputs when low. Internal pull-up resistor. Select input S2. Selects ACLK per table above. Internal pull-up resistor. Audio clock output per table above. Connect to ground. 27 MHz reference clock output. Select input S0. Selects ACLK per table above. Internal pull-up resistor.
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MK3724 VCXO PLUS AUDIO CLOCK FOR STB
Pin Number
14 15 16
Pin Name
VDD NC S1
Pin Type
Power -Input Connect to +3.3 V.
Pin Description
No connect. Do not connect anything to this pin. Select input S1. Selects ACLK per table above. Internal pull-up resistor.
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MK3724 VCXO PLUS AUDIO CLOCK FOR STB
External Component Selection
The MK3724 requires a minimum number of external components for proper operation.
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 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 samples of the crystals which you plan to use in production. You will also need measured initial accuracy for each crystal at the specified crystal load capacitance (CL). To determine the value of the crystal capacitors: 1. Connect VDD to 3.3 V. Connect pin 5 to the second power supply. Adjust the voltage on pin 5 to 0V. Measure and record the frequency of the CLK output. 2. Adjust the voltage on pin 5 to 3.3 V. Measure and record the frequency of the same output. To calculate the centering error:
6 ( f 3.3 ( 3.0 )V - f t arg et ) + ( f 0V - f t arg et ) Error = 10 x ---------------------------------------------------------------------------------------- - error xtal f t arg et
Decoupling Capacitors
Decoupling capacitors of 0.01 F should be connected between VDD and GND on pins 3 and 4, pins 6 and 7, and pins 11 and 14 as close to the MK3724 as possible. For optimum device performance, the decoupling capacitors 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 traces between the clock outputs and the loads are over 1 inch, series termination should be used. To series terminate a 50 trace (a commonly used trace impedance), place a 33 resistor in series with the clock line, as close to the clock output pin as possible. The nominal impedance of the clock output is 20 .
Quartz Crystal
The MK3724 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 meeting ICS' recommended parameters must be used, and the layout guidelines discussed in the following section must be followed. See Application Note MAN05 for a full list of crystal parameters. The frequency of oscillation of a quartz crystal is determined by its "cut" and by the load capacitors connected to it. The MK3724 incorporates on-chip variable load capacitors that "pull" (change) the frequency of the crystal. The crystal specified for use with the MK3724 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 the MK3724. There should be no via's between the crystal pins and the X1 and X2 device pins. There should be no signal traces underneath or close to the crystal.
Where: ftarget = nominal crystal frequency errorxtal =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 ICS for details.) If the centering error is more than 25 ppm positive, add identical fixed centering capacitors from each crystal pin to ground. The value for each of these caps (in pF) is given by:
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MK3724 VCXO PLUS AUDIO CLOCK FOR STB
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 MK3724. These ratings, which are standard values for ICS 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 Ambient Operating Temperature, Industrial Storage Temperature Soldering Temperature 7V
Rating
-0.5 V to VDD+0.5 V 0 to +70C -40 to +85C -65 to +150C 260C
Recommended Operation Conditions
Parameter
Ambient Operating Temperature, Commercial Ambient Operating Temperature, Industrial Power Supply Voltage (measured in respect to GND) Reference crystal parameters
Min.
0 -40 +3.135
Typ.
Max.
+70 +85 +3.465
Units
C C V
Refer to page 3
DC Electrical Characteristics
VDD=3.3 V 5% , Ambient temperature -40 to +85C, unless stated otherwise
Parameter
Operating Voltage Output High Voltage Output Low Voltage Output High Voltage (CMOS Level) Output Low Voltage (CMOS Level)
Symbol
VDD VOH VOL VOH VOL
Conditions
IOH = -12 mA IOL = 12 mA IOH = -4 mA IOH = +4 mA
Min.
3.135 2.4
Typ.
Max.
3.465 0.4
Units
V V V V
VDD-0.4 0.375
V
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MK3724 VCXO PLUS AUDIO CLOCK FOR STB
Parameter
Input High Voltage (S1:S0) Input High Voltage (S2) Input Low Voltage (S1:S0) Input Low Voltage (S2) Input High Current Input Low Current Operating Supply Current Short Circuit Current VIN, VCXO Control Voltage On Chip Pull-up Resistor, inputs Input Capacitance Nominal Output Impedance
Symbol
VIH VIH VIL VIL IIH IIL IDD IOS VIA RPU CIN ZOUT
Conditions
Min.
2.0 2.5
Typ.
Max.
Units
V V
0.8 0.5 at 3.3V, Sx, PDTS at 0V, Sx, PDTS No load 0 Input selects Input selects 360 5 20 0.1 -8.5 11 50 3.3
V V A A mA mA V k pF
AC Electrical Characteristics
VDD = 3.3 V 5%, Ambient Temperature -40 to +85 C, unless stated otherwise
Parameter
Crystal Pullability VCXO Gain Output Rise Time Output Fall Time Output Clock Duty Cycle Maximum Output Jitter, short term Changing Frequency Setting Time Power-up time
Symbol
fP tOR tOF tD tJ
Conditions
0V< VIN < 3.3 V, Note 1 VIN = VDD/2 + 1 V, Note 1 20% to 80%, CL=15 pF 80% to 20%, CL=15 pF Measured at 1.65 V, CL=15 pF CL=15 pF
Min.
+ 100
Typ.
+ 150 150 1.2 1.2
Max. Units
ppm ppm/V 2.0 2.0 60 ns ns % ps 1 ms ms ms
40
50 +150
PLL lock time from power-up up to 1% of final frequency PDTS goes high until stable CLK output up to 1% of final frequency
10 2
Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3.
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MK3724 VCXO PLUS AUDIO CLOCK FOR STB
Thermal Characteristics
Parameter
Thermal Resistance Junction to Ambient
Symbol
JA JA JA JC
Conditions
Still air 1 m/s air flow 3 m/s air flow
Min.
Typ.
78 70 68 37
Max. Units
C/W C/W C/W C/W
Thermal Resistance Junction to Case
Marking Diagram
16 9
Notes: 1. ###### is the lot code. 2. YYWW is the last two digits of the year, and the week number that the part was assembled. 3. "L" designates Pb (lead) free. 4. Bottom mark denotes country of origin if not USA.
MK3724G ###### YYWW
1
Non Lead-Free
8
16
9
MK3724GL ###### YYWW
1
Lead-Free
8 9
16
MK3724IL ###### YYWW
1
Industrial Temp., Lead-Free
8
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MK3724 VCXO PLUS AUDIO CLOCK FOR STB
Package Outline and Package Dimensions (16-pin TSSOP, 4.40 mm Body, 0.65 mm Pitch)
Package dimensions are kept current with JEDEC Publication No. 95Ordering Information
16
Millimeters Symbol Min Max
Inches Min Max
E1 INDEX AREA
E
12 D
A A1 A2 b C D E E1 e L
-1.20 0.05 0.15 0.80 1.05 0.19 0.30 0.09 0.20 4.90 5.1 6.40 BASIC 4.30 4.50 0.65 Basic 0.45 0.75 0 8
-0.047 0.002 0.006 0.032 0.041 0.007 0.012 0.0035 0.008 0.193 0.201 0.252 BASIC 0.169 0.177 0.0256 Basic 0.018 0.030 0 8
A 2 A 1
A
c
-Ce
b SEATING PLANE L
.10 (.004)
C
Part / Order Number
MK3724G MK3724GTR MK3724GLF MK3724GLFTR MK3724GILF MK3724GILFTR
Marking
MK3724G MK3724G MK3724GL MK3724GL MK3724IL MK3724IL
Shipping packaging
Tubes Tape and Reel Tubes Tape and Reel Tubes Tape and Reel
Package
16-pin TSSOP 16-pin TSSOP 16-pin TSSOP 16-pin TSSOP 16-pin TSSOP 16-pin TSSOP
Temperature
0 to +70 C 0 to +70 C 0 to +70 C 0 to +70 C -40 to +85 C -40 to +85 C
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems (ICS) assumes no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in normal commercial applications. Any other applications such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements are not recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does not authorize or warrant any ICS product for use in life support devices or critical medical instruments.
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