PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer Description Features The ICS276 field programmable VCXO clock synthesizer generates up to three high-quality, high-frequency clock outputs including multiple reference clocks from a low-frequency crystal input. It is designed to replace crystals and crystal oscillators in most electronic systems. • • • • • • • • • • • Using ICS’ VersaClockTM software to configure PLLs and outputs, the ICS276 contains a One-Time Programmable (OTP) ROM for field programmability. Programming features include VCXO and eight selectable configuration registers. Each of the outputs are powered by a single VDDO voltage. VDDO may vary from 1.8 V to VDD. Packaged as 16-pin TSSOP Eight addressable registers Replaces multiple crystals and oscillators Output frequencies up to 200 MHz at 3.3 V Input crystal frequency of 5 to 27 MHz Up to three reference outputs Operating voltages of 3.3 V VDDO output control from 1.8 V to 3.3 V Controllable output drive levels Advanced, low-power CMOS process Available in Pb (lead) free packaging Using Phase-Locked Loop (PLL) techniques, the device runs from a standard fundamental mode, inexpensive crystal, or clock. It can replace VCXOs, multiple crystals and oscillators, saving board space and cost. The ICS276 is also available in factory programmed custom versions for high-volume applications. Block Diagram VDD S2:S0 3 OTP ROM with PLL Values 3 VDDO PLL1 CLK1 Divide Logic and Output Enable Control PLL2 VIN CLK2 PLL3 X1 CLK3 Voltage Controlled Crystal Oscillator Crystal X2 GND External capacitors are required. 2 PDTS 1 MDS 276 A Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 Revision 040805 ● tel (408) 297-1201 ● www.icst.com PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer Pin Assignment VIN VDDO CLK1 GND 1 2 3 4 5 6 7 16 15 14 13 12 11 10 X1/ICLK 8 9 S0 S1 VDD S2 VDD PDTS GND CLK3 CLK2 VDD X2 16 pin (173 mil) TSSOP Pin Descriptions Pin Number Pin Name Pin Type 1 VIN Input 2 S0 Input 3 S1 Input 4 VDD Power Select pin 1. Internal pull-up resistor. Connect to +3.3 V. 5 VDDO Power Power supply for outputs. 6 CLK1 Output Output clock 1. Weak internal pull-down when tri-state. 7 GND Power Connect to ground. 8 X1 XI Crystal input. Connect this pin to a crystal. 9 X2 XO Pin Description Voltage input to VCXO. Zero to 3.3 V signal which controls the VCXO frequency Select pin 0. Internal pull-up resistor. 10 VDD Power Crystal Output. Connect this pin to a crystal. Connect to +3.3 V. 11 CLK2 Output Output clock 2. Weak internal pull-down when tri-state. 12 CLK3 Output Output clock 3. Weak internal pull-down when tri-state. 13 GND Power Connect to ground. 14 PDTS Input 15 VDD Power Power-down tri-state. Powers down entire chip and tri-states clock outputs when low. Internal pull-up resistor. Connect to +3.3 V. 16 S2 Input Select pin 2. Internal pull-up resistor. 2 MDS 276 A Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 Revision 040805 ● tel (408) 297-1201 ● www.icst.com PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer External Components The ICS276 requires a minimum number of external components for proper operation. Series Termination Resistor Clock output traces over one inch should use series termination. 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. Decoupling Capacitors As with any high-performance mixed-signal IC, the ICS276 must be isolated from system power supply noise to perform optimally. Decoupling capacitors of 0.01µF must be connected between each VDD and the PCB ground plane. For optimum device performance, the decoupling capacitor should be mounted on the component side of the PCB. Avoid the use of vias on the decoupling circuit. Quartz Crystal The ICS276 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 (shown below) must be used, and the layout guidelines discussed in the following section shown 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 ICS276 incorporates on-chip variable load capacitors that “pull” (change) the frequency of the crystal. The crystal specified for use with the ICS276 is designed to have zero frequency error when the total of on-chip + stray capacitance is 14 pF. Recommended Crystal Parameters: Initial Accuracy at 25°C Temperature Stability Aging Load Capacitance Shunt Capacitance, C0 C0/C1 Ratio Equivalent Series Resistance 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 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, CL. To determine the value of the crystal capacitors: 1. Connect VDD of the ICS276 to 3.3 V. Connect pin 1 of the ICS276 to the second power supply. Adjust the voltage on pin 1 to 0V. Measure and record the frequency of the CLK output. 2. Adjust the voltage on pin 1 to 3.3 V. Measure and record the frequency of the same output. To calculate the centering error: 6 ( f3.0V – ft arg et ) + ( f0V – ft arg et ) Error = 10 x ----------------------------------------------------------------------- – errorxtal ft arg et Where: ftarget = nominal crystal frequency 3 MDS 276 A Integrated Circuit Systems, Inc. ±20 ppm ±30 ppm ±20 ppm 14 pf 7 pF Max 250 Max 35Ω Max 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 ICS276. 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. See application note MAN05. ● 525 Race Street, San Jose, CA 95126 Revision 040805 ● tel (408) 297-1201 ● www.icst.com PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer 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: 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). ICS276 Configuration Capabilities The architecture of the ICS276 allows the user to easily configure the device to a wide range of output frequencies, for a given input reference frequency. The frequency multiplier PLL provides a high degree of precision. The M/N values (the multiplier/divide values available to generate the target VCO frequency) can be set within the range of M = 1 to 1024 and N = 1 to 32,895. The ICS276 also provides separate output divide values, from 2 through 63, to allow the two output clock banks to support widely differing frequency values from the same PLL. Each output frequency can be represented as: OutputFreq = REFFreq ----⋅M N Output Drive Control The ICS271 has two output drive settings. For VDDO=VDD, low drive should be selected when outputs are less than 100 MHz. High drive should be selected when outputs are greater than 100 MHz. For VDDO<2.8V, high drive should be selected for all output frequencies. (Consult the AC Electrical Characteristics for output rise and fall times for each drive option.) ICS VersaClock Software ICS applies years of PLL optimization experience into a user friendly software that accepts the user’s target reference clock and output frequencies and generates the lowest jitter, lowest power configuration, with only a press of a button. The user does not need to have prior PLL experience or determine the optimal VCO frequency to support multiple output frequencies. VersaClock software quickly evaluates accessible VCO frequencies with available output divide values and provides an easy to understand, bar code rating for the target output frequencies. The user may evaluate output accuracy, performance trade-off scenarios in seconds. Absolute Maximum Ratings Stresses above the ratings listed below can cause permanent damage to the ICS276. 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. Parameter Condition Supply Voltage, VDD Referenced to GND Inputs Referenced to GND Clock Outputs Referenced to GND Typ. Max. Units 7 V -0.5 VDD+0.5 V -0.5 VDD+0.5 V 4 MDS 276 A Integrated Circuit Systems, Inc. Min. ● 525 Race Street, San Jose, CA 95126 Revision 040805 ● tel (408) 297-1201 ● www.icst.com PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer Parameter Condition Min. Storage Temperature Typ. Max. Units 150 °C 260 °C 125 °C -65 Soldering Temperature Max 10 seconds Junction Temperature Recommended Operation Conditions Parameter Min. Typ. Max. Units Ambient Operating Temperature (ICS276PG/PGLF) 0 +70 °C Ambient Operating Temperature (ICS276PGI/PGILF) -40 +85 °C Power Supply Voltage (measured in respect to GND) +3.135 +3.465 V 4 ms +3.3 Power Supply Ramp Time Reference crystal parameters Refer to page 3 DC Electrical Characteristics Unless stated otherwise, VDD = 3.3 V ±5%, Ambient Temperature -40 to +85°C Parameter Symbol Operating Voltage Conditions Min. VDD VDDO Voltage Typ. Max. Units 3.135 3.465 V 1.80 VDD V Config. Dependent - See VersaClockTM Estimates Operating Supply Current Input High Voltage IDD mA Three 33.3333 MHz outs, VDD=VDDO=3.3 V; PDTS = 1, no load, Note 1 20 mA 500 µA V Input High Voltage VIH PDTS = 0, no load, Note 1 S2:S0 Input Low Voltage VIL S2:S0 Input High Voltage, PDTS VIH Input Low Voltage, PDTS VIL Input High Voltage VIH ICLK Input Low Voltage VIL ICLK Output High Voltage (CMOS High) VOH IOH = -4 mA Output High Voltage VOH IOH = -8 mA (Low Drive); IOH = -12 mA (High Drive) Output Low Voltage VOL IOL = 8 mA (Low Drive); IOL = 12 mA (High Drive) Short Circuit Current IOS Low Drive ±40 High Drive ±70 mA 20 Ω Nom. Output Impedance 0.4 VDD-0.5 0.4 VDD/2+1 ● 525 Race Street, San Jose, CA 95126 V V VDD/2-1 V VDD-0.4 V 2.4 VDDO-0.4 V 0.4 ZO V V 5 MDS 276 A Integrated Circuit Systems, Inc. VDD/2+1 V Revision 040805 ● tel (408) 297-1201 ● www.icst.com PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer Parameter Symbol Conditions Min. Typ. Max. Units Internal pull-up resistor RPUS S2:S0, PDTS 190 kΩ Internal pull-down resistor RPD CLK outputs 120 kΩ Input Capacitance CIN Inputs 4 pF Note 1: Example with 25 MHz crystal input, three unloaded 33.3 MHz outputs and VDD = VDDO = 3.3 V. AC Electrical Characteristics Unless stated otherwise, VDD = 3.3 V ±5%, Ambient Temperature -40 to +85° C Parameter Symbol Input Frequency Conditions FIN Fundamental crystal Output Frequency Crystal Pullability Min. FP Max. Units 5 27 MHz VDDO=VDD 0.314 200 MHz 1.8 V<VDDO<2.8 0.314 150 MHz 0V< VIN < 3.3 V, Note 1, Config. Dependent VCXO Gain Typ. 100 ppm VIN = VDD/2 + 1 V, Note 1, Config. Dependent 120 ppm/V Output Rise/Fall Time tOF 80% to 20%, high drive, Note 2 1.0 ns Output Rise/Fall Time tOF 80% to 20%, low drive, Note 2 2.0 ns Duty Cycle Note 3 Power-up Time PLL lock-time from power-up One Sigma Clock Period Jitter Maximum Absolute Jitter tja 40 49-51 60 % 4 10 ms PDTS goes high until stable CLK output 0.6 2 ms Configuration Dependent 50 ps Deviation from Mean. Configuration Dependent +200 ps Note 1: External crystal device must conform with Pullable Crystal Specifications listed on page 3. Note 2: Measured with 15 pF load. Note 3: Duty Cycle is configuration dependent. Most configurations are min 45% / max 55%. 6 MDS 276 A Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 Revision 040805 ● tel (408) 297-1201 ● www.icst.com PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer Thermal Characteristics 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 Case θJC 37 °C/W Marking Diagrams Marking Diagrams (Pb free) 16 16 9 9 276PGL ###### YYWW 276PG ###### YYWW 1 8 1 8 16 9 16 9 276PGIL ###### YYWW 276PGI ###### YYWW 1 1 8 8 Notes: 1. ###### is the lot number. 2. YYWW is the last two digits of the year and week that the part was assembled. 3. “I” denotes industrial temperature range (if applicable). 4. “L” denotes Pb (lead) free package. 5. Bottom marking: country of origin. 7 MDS 276 A Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 Revision 040805 ● tel (408) 297-1201 ● www.icst.com PRELIMINARY INFORMATION ICS276 Triple PLL Field Programmable VCXO Clock Synthesizer Package Outline and Package Dimensions (16-pin TSSOP, 173 Mil. Body) Package dimensions are kept current with JEDEC Publication No. 95 24 Millimeters Symbol E1 INDEX AREA Min A A1 A2 b C D E E1 e L α E 1 2 D Inches Max Min — 1.20 0.05 0.15 0.80 1.05 0.19 0.30 0.09 0.20 4.90 5.10 6.40 BASIC 4.30 4.50 0.65 Basic 0.45 0.75 0° 8° Max — .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 .018 .030 0° 8° A A2 A1 c - Ce SEATING PLANE b .10 (.004) L C Ordering Information Part / Order Number Marking Shipping Packaging Package Temperature Tubes 16-pin TSSOP 0 to +70°C ICS276PG ICS276PGI See page 7 Tubes 16-pin TSSOP -40 to +85°C ICS276PGLF Tubes 16-pin TSSOP 0 to +70°C ICS276PGILF Tubes 16-pin TSSOP -40 to +85°C Parts that are ordered with a "LF" suffix to the part number are the Pb-Free configuration and are RoHS compliant. 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. VersaClockTM is a trademark of Integrated Circuit Systems, Inc. All rights reserved. 8 MDS 276 A Integrated Circuit Systems, Inc. ● 525 Race Street, San Jose, CA 95126 Revision 040805 ● tel (408) 297-1201 ● www.icst.com