MK3722 ICST | Alldatasheet
Document overview
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- PDF pages: 6
Technical content
Features
- Packaged in 16 pin TSSOP
- Replaces a VCXO and oscillator
- Operating voltage of 3.3V
- 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 Block Diagram Voltage Controlled Crystal Oscillator VIN
27 MHz
S2:S0 VDD GND PDTS
VCXO PLUS AUDIO CLOCK FOR STB Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com MK3722 Pin Assignment Pin Descriptions Audio Clock Select Table VDD NC VDD VIN VDD 27M GND GND GND ACLK PDTS 16 Pin 4.40mm body, 0.65mm pitch TSSOP S2 S1 S0 ACLK (MHz) 000 8 . 1 9 2 0 0 1 11.2896 0 1 0 12.288 0 1 1 16.9344 1 0 0 18.432 1 0 1 16.384 1 1 0 22.5792 1 1 1 24.576 Pin Number Pin Name Pin Type Pin Description 1 X2 Output Crystal connection. Connect to a 27MHz fundamental mode pullable crystal. 2 X1 Input Crystal connection. Connect to a 27MHz fundamental mode pullable crystal. 3 VDD Power Connect to +3.3 V. 4 VDD Power Connect to +3.3 V. 5 VIN Input Voltage input to VCXO. Zero to 3.3V signal which controls the VCXO frequency. 6 GND Power Connect to ground. 7 GND Power Connect to ground. 8P D T S Power Power Down Tri-state. This pin powers down entire chip and tri-states the outputs when low. Internal pull-up. 9 S2 Input Select input S2. Selects ACLK per table above. Internal pull-up. 10 ACLK Output Audio clock output per table above. 11 GND Power Connect to ground. 12 27M Output 27MHz reference clock output. 13 S0 Input Select input S0. Selects ACLK per table above. Internal pull-up. 14 VDD Power Connect to +3.3V. 15 NC -- No connect. Do not connect anything to this pin. 16 S1 Input Select input S1. Selects ACLK per table above. Internal pull-up.
VCXO PLUS AUDIO CLOCK FOR STB Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com MK3722 External Component Selection The MK3722 requires a minimum number of external components for proper operation. Decoupling Capacitors Decoupling capacitors of 0.01µF 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 MK3722 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 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 MK3722 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 MK3722 incorporates on-chip variable load capacitors that “pull” (change) the frequency of the crystal. The crystal specified for use with the MK3722 is designed to have zero frequency error when the total of on-chip + stray capacitance is 14pF. 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 MK3722. 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. 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 (C L). To determine the value of the crystal capacitors: 1. Connect VDD to 3.3V. 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 3.3V. Measure and record the frequency of the same output. To calculate the centering error: Where: f target = 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 25ppm 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 25ppm positive, add identical fixed centering capacitors from each crystal pin to ground. The value for each of these caps (in pF) is given by: Error 10 6x f3.3 3.0() V fte targ–() f0V fte targ–()+ fte targ
VCXO PLUS AUDIO CLOCK FOR STB Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com MK3722 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 ±25ppm). Absolute Maximum Ratings Stresses above the ratings listed below can cause permanent damage to the MK3722. 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. Recommended Operation Conditions VDD=3.3V ±5% , Ambient temperature 0 to +70°C, unless stated otherwise Item Rating Supply Voltage, VDD 7V All Inputs and Outputs -0.5V to VDD+0.5V Ambient Operating Temperature 0 to +70 °C Storage Temperature -65 to +150 °C Soldering Temperature 260 °C Parameter Min. Typ. Max. Units Ambient Operating Temperature 0 +70 °C Power Supply Voltage (measured in respect to GND) +3.15 +3.45 V Reference crystal parameters Refer to page 3 Parameter Symbol Conditions Min. Typ. Max. Units Operating Voltage VDD 3.15 3.45 V Output High Voltage V OH IOH = -12 mA 2.4 V Output Low Voltage V OL IOL = 12 mA 0.4 V Output High Voltage (CMOS Level) VOH IOH = -4 mA VDD-0.4 V Input High Voltage (S1:S0) V IH 2.0 V Input High Voltage (S2) V IH 2.5 V Input Low Voltage (S1:S0) V IL 0.8 V Input Low Voltage (S2) V IL 0.5 V
VCXO PLUS AUDIO CLOCK FOR STB Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com MK3722 VDD = 3.3V ±5% , Ambient Temperature 0 to +70° C, unless stated otherwise Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3. Thermal Characteristics Operating Supply Current IDD No load, 2 outputs 11 mA Short Circuit Current I OS ±50 mA VIN, VCXO Control Voltage V IA 03 . 3 V On Chip Pull-up Resistor, inputs R PU S0, S1, S2 150 k Ω Input Capacitance C IN S0, S1, S2 5 pF Nominal Output Impedance Z OUT 20 Ω Parameter Symbol Conditions Min. Typ. Max. Units Crystal Pullability f P 0V< VIN < 3.3V, Note 1 + 100 ppm VCXO Gain VIN = VDD/2 + 1V, Note 1 80 ppm/V Output Rise Time t OR 0.8 to 2.0V, CL=15pF 0.75 1.5 ns Output Fall Time t OF 2.0 to 0.8V, CL=15pF 0.75 1.5 ns Output Clock Duty Cycle t D Measured at 1.65V, CL=15pF 40 50 60 % Maximum Output Jitter, short term tJ C L=15pF + 150 ps Parameter Symbol Conditions Min. Typ. Max. Units Thermal Resistance Junction to Ambient θJA Still air 78 °C/W θJA 1 m/s air flow 70 °C/W θJA 3 m/s air flow 68 °C/W Thermal Resistance Junction to CaseθJC 37 °C/W Parameter Symbol Conditions Min. Typ. Max. Units
VCXO PLUS AUDIO CLOCK FOR STB Integrated Circuit Systems ● 525 Race Street, San Jose, CA 95126 ● tel (408) 295-9800 ● www.icst.com MK3722 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. 95
Ordering Information
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. Part / Order Number Marking Shipping packaging Package Temperature MK3722G MK3722G Tubes 16 pin TSSOP 0 to +70 ° C MK3722GTR MK3722G Tape and Reel 16 pin TSSOP 0 to +70 ° C INDEX AREA 1 2 D E1 E SEATING PLANE A AA e - C - b .10 (.004)C α c L Millimeters Inches Symbol Min Max Min Max A -- 1.20 -- 0.047 A1 0.05 0.15 0.002 0.006 A2 0.80 1.05 0.032 0.041 b 0.19 0.30 0.007 0.012 C 0.09 0.20 0.0035 0.008 D 4.90 5.1 0.193 0.201 E 6.40 BASIC 0.252 BASIC E1 4.30 4.50 0.169 0.177 e 0.65 Basic 0.0256 Basic L 0.45 0.75 0.018 0.030 α 0° 8° 0° 8°