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PI6C3421A
27MHz Spread Spectrum Clock Synthesizer
Product Features
* 14.318 MHz input frequency, (crystal or external reference) * Two High Precision outputs: --27.000 MHz SSC clock output --27.000 MHz clock output * Four Down-Spread options: -- Down-spread: -0.25%, -0.5%, -0.75% and -1.0% typical at 14.318MHz input * Single 3.3V Power Supply * Modulation Rate: Fin /448 * Industrial and commercial temperature supported * Packaging ( Pb-Free and Green): -- SOTinyTM 6-pin SOT-23 (T) Applications The PI6C3421A can be used in most multimedia applications and embedded systems including but not limited to the following: * PDAs * DSCs * Printers/ MFPs * Media players * Portable-TVs * Embedded digital video devices * CD-ROM, VCD and DVD players * LCD Panel Modules * Automotive components * Networking devices Benefits * Reduction in EMI * System cost saving * Reduced system complexity * Faster time to market
Description
The PI6C3421A is a Spread Spectrum Clock Synthesizer and part of the Pericom SSCG product family. The part generates one high precision 27.000 MHz spread spectrum clock output from a single clock source or a crystal and one 27.000 MHz un-modulated clock output, and is designed to reduce electromagnetic interference (EMI) by spreading the clock. This reduction in EMI can result in significant system cost saving and less design complexity by reducing the number of circuit board layers ferrite beads and shielding. In the absence of a spread spectrum clock, other EMI-reducing components are required in order to comply with regulatory agency requirements. The spreading ratio is selectable using the selection pins. The PI6C3421A provides -0.25%, -0.5%, -0.75% and -1.0% spread modulation through external logic stage setting. The variety and the reduced size of the package outlines can save precious board space and make layout easier. PI6C3421A is one of the clock products provided by Pericom. If your application needs a clock product with a different specification not currently provided, please contact us for further information or custom design.
Block Diagram
Pin Configuration
REFIN/X1 X2 S0 S1
27M Clock Synthesizer 27M_SSC
X1/REFIN GND 27M_SSC/S0 6-Pin SOT-23
X2/S1 VDD 27M
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PI6C3421A 27MHz Spread Spectrum Clock Synthesizer
Pin Description
Pin Name X1/REFIN GND 27M_SSC/S0 Pin No 1 2 3 I/O Type I Ground I/O Description Crystal or reference clock input Ground 27M_SSC/SO is a multi-functional pin. S0 is active during power on for spreading ratio selection then switches to 27MHz SSC clock output. 27MHz clock output. Power Supply X2/S1 is a multiple function pin. S1 is active during power on selection of SSC spread then switches to crystal input.
27M VDD X2/S1
4 5 6
O Power I/O
Spread Ration Configuration
(VDD = 3.3V 10%, Ambient Temperature = 25C, fOUT = 27 MHz) S0 0 0 1 1 S1 0 1 0 1 Down - Spread(%) -0.25 -0.5 -0.75 -1.0
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Electrical Specifications
Maximum Ratings(1)
Supply Voltage to Ground ....................................................................... 5.5V All Inputs and Outputs ..................................................... -0.5V to VDD+0.5V Storage Temperature .............................................................-65C to +150C Operating Temperature ............................................................... -40 to +85C Junction Temperature ............................................................................150C Soldering Temperature ..........................................................................260C
Note: 1. Stresses greater than those listed under MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
DC Characteristics (VDD = 3.3V 10%, Ambient Temperature -40C to +85oC, fIN = 14.318 MHz)
Symbol VDD VIH VIL VOH VOH VOL VOL IDD ZOUT_UP CIN Parameter Operating Voltage Input High Voltage Input Low Voltage Output High Voltage Output High Voltage Output Low Voltage Output Low Voltage Supply Current Nominal Output Impedance Input Capacitance Conditions Min. +3.0 2 2.4 2.0 0.4 0.6 55 65 40 6 Typ.(1) +3.3 Max. +3.6 0.8 IOH = -4 mA IOH = -6 mA IOL = 4 mA IOL = 6 mA All outputs active with CL = 15pF load High side buffer Input pins Unit V V V V V V V mA pF
ZOUT_LOW Nominal Output Impedance Low side buffer
AC Characteristics (VDD = 3.3V 10%, Ambient Temperature -40C to +85oC)
Parameter Conditions REFIN Input Frequency REFIN Clock Input Clock Output Frequency Multiplication factor (fIN/fOUT = 1.885715) Output Clock Rise Time From 0.4V to 2.4V, CL = 15pF load Output Clock Fall Time From 2.4V to 0.4V, CL = 15pF load TJ_SHORT Short term jitter Cycle-to-cycle jitter (fOUT = 27 MHz) Input Clock Duty Cycle REFIN/X1, Measured @ VDD/2 (fOUT = 27 MHz) TIDC Output Clock Duty Measured @ VDD/2 (fOUT = 27 MHz) TODC Cycle / Actual mean frequency Input frequency = 14.31818 MHz, Output freerror versus target quency = 27 MHz
Note: 1. Typical conditions are at 3.3V for room temperature at 25C
Symbol fIN fOUT tRISE tFALL
Min. 8 15.1
20 45
Typ.(1) 14.318 27 3 2.7 250 50 50 0
Max. 24.5 46.2
350 80 55
Unit MHz MHz ns ns ps % % ppm
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Application Information
Decoupling Capacitor Two decoupling capacitors of 0.1uF and 1nF must be connected in parallel between VDD and GND. To optimize device performance and to lower output noise, the coupling capacitors should be placed on the component side of the board as close to these pins as possible. There should be no vias placed between the decoupling capacitors and VDD pin. The PCB trace to VDD pin should be as short as possible, and no vias should be placed between VDD and the capacitors in the decoupling circuit. 10k to 50k pull-up or pull-down resistors, depending on the application, should be used on S0 and S1 to select the logical state and corresponding spreading ratio.
VDD
0.1uF 1nF 0.1uF 1nF
VDD
VDD
S0/ S1
Connect to low
S0/ S1
Connect to high
1. PI6C3421A can accept a 14.31818 MHz reference clock or crystal clock. 2. Power supply pin decoupling capacitors should be placed as close as possible to VDD pin. Via's at the VDD pin should be avoided. 3. Spread select pin's (S0 and S1): Pin 3 (27M_SSC/S0) and Pin 6 (X2/S1) provide logic state strapping function. When strapping resistor connects to VDD, S0 and S1 are set to logic HIGH. When strapping resistor connects to Ground, S0 or S1 will set to logic LOW. 4. Refer to "Spread Spectrum Selection Table", for more details on the strapping logic.
Crystal Load Capacitors
If a crystal is used with the device, the external trim capacitors CLtrim are used to adjust the effective capacitance to match the required crystal load capacitance. The CLtrim value can be derived from formula CLtrim = 2*CL - (Cs + Ci). Typical CLtrim = 28pF when crystal load = 18pF, stray capacitance Cs = 3pF and XTAL pins capacitance = 5pF.
Xtal
X1 CLtrim
X2 CLtrim
Series Termination Resistor
For optimal performance, a series termination resistor should be used, when the PCB trace between the clock output and the load is over 1 inch. A 10 resistor should be used to series terminate a 50 trace, a typical trace impedance found on PCB boards. The series termination resistor should be placed in series and as close to the clock output as possible. The nominal impedance measured at the clock output of the part is 40.
PCB Layout Recommendation
To optimize device performance, all components should be placed on the same side of the board and, therefore, no vias are used through other signal layers. The part should be kept away from other signal traces including ones just underneath the part or on layers adjacent to the ground plane layer used by the part. The PCB trace from the part to the ground via should be kept as short as possible
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PI6C3421A 27MHz Spread Spectrum Clock Synthesizer Recommended Crystal Specification Pericom recommends SRX7316-E Crystal for optimum performance. Parameter Value Mode of oscillation, and cut Fundamental AT Frequency 14.318 Frequency Tolerance 20 Temperature 30 Load Cap 18 Equivalent series resistance 40 Drive to level 100 Aging Stability 5 Size (Length x Width x Height) 11.18(.440) x 4.65(.83) x 13.46(.53)
Units MHz PPM PPM pF W PPM/YR mm(inch)
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PI6C3421A 27MHz Spread Spectrum Clock Synthesizer Packaging Mechanical: 6-Pin, SOT23
0.075 1.90 BSC
DOCUMENT CONTROL NO. PD - 1912 REVISION: C DATE: 03/09/05 4
0.059 1.50 0.068 1.75 0.102 2.60 0.118 3.00 0 - 10 Datum "A"
6
5
2
3
0.037 0.95 BSC
0.004 0.10 0.023 0.60 0.014 0.35 0.019 0.50
0.110 2.80 0.118 3.00
0.057 1.45 MAX. SEATING PLANE 0.000 0.00 0.005 0.15 X.XX DENOTES DIMENSIONS X.XX IN MILLIMETERS
Notes: 1) Controlling dimensions in millimeters 2) Ref: EIAJ SC-74A 3) Foot length is measured at flat portion of foot, reference to Datum "A"
Pericom Semiconductor Corporation 3545 N. 1st Street, San Jose, CA 95134 1-800-435-2335 * www.pericom.com
DESCRIPTION: 6-Pin Small Outline Transistor Plastic Package, SOT-23 PACKAGE CODE: T
Ordering Information(1-3)
Ordering Code PI6C3421ATE PI6C3421AITE Package Code T T PackageType Pb-free & Green, 6-Pin SOT-23 Pb-free & Green, 6-Pin SOT-23
Notes: 1. Thermal characteristics and package top marking information can be found at http://www.pericom.com/packaging/ 2. I= Industrial Temperature (-40~+85C) 3. E=Pb-free and Green package 4. Adding an X suffix=Tape/Reel
Pericom Semiconductor Corporation * 1-800-435-2336 * www.pericom.com
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Disclaimer The information contained herein is subject to change without notice. While the information presented herein has been checked for both accuracy and reliability, Pericom Semiconductor Corporation (PSC) 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. PSC products are not warranted nor intended to be used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with PSC. Furthermore, PSC does not authorize its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of PSC products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies PSC against all charges.
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