SEMICONDUCTOR TECHNICAL DATA The MC12439 is a general purpose synthesized clock source targeting applications that require both serial and parallel interfaces. Its internal VCO will operate over a range of frequencies from 400 to 800MHz. The differential PECL output can be configured to be the VCO frequency divided by 1, 2, 4, or 8. With the output configured to divide the VCO frequency by 1, and with a 16.66MHz external quartz crystal used to provide the reference frequency, the output frequency can be specified in 16.66MHz steps. HIGH FREQUENCY PLL CLOCK GENERATOR • • • • • • • • • 50 to 800MHz Differential PECL Outputs ±25ps Typical Peak–to–Peak Output Jitter Minimal Frequency Over–Shoot Synthesized Architecture Serial 3–Wire Interface Parallel Interface for Power–Up FN SUFFIX 28–LEAD PLCC PACKAGE CASE 776–02 Quartz Crystal Interface 28–Lead PLCC Package Operates from 3.3V or 5.0V Power Supply Functional Description The internal oscillator uses the external quartz crystal as the basis of its frequency reference. The output of the reference oscillator is sent directly to the phase detector. With a 16.66MHz crystal, this provides a reference frequency of 16.66MHz. Although this data sheet illustrates functionality only for a 16MHz and 16.66MHz crystal, any crystal in the 10–20MHz range can be used. In addition to the crystal, an LVCMOS input can also be used as the PLL reference. The reference is selected via the XTAL_SEL input pin. The VCO within the PLL operates over a range of 400 to 800MHz. Its output is scaled by a divider that is configured by either the serial or parallel interfaces. The output of this loop divider is also applied to the phase detector. The phase detector and loop filter attempt to force the VCO output frequency to be M times the reference frequency by adjusting the VCO control voltage. Note that for some values of M (either too high or too low) the PLL will not achieve loop lock. The output of the VCO is also passed through an output divider before being sent to the PECL output driver. This output divider is configured through either the serial or the parallel interfaces, and can provide one of four division ratios (1, 2, 4, or 8). This divider extends performance of the part while providing a 50% duty cycle. The output driver is driven differentially from the output divider, and is capable of driving a pair of transmission lines terminated in 50Ω to VCC – 2.0. The configuration logic has two sections: serial and parallel. The parallel interface uses the values at the M[6:0] and N[1:0] inputs to configure the internal counters. Normally, on system reset, the P_LOAD input is held LOW until sometime after power becomes valid. On the LOW–to–HIGH transition of P_LOAD, the parallel inputs are captured. The parallel interface has priority over the serial interface. Internal pullup resistors are provided on the M[6:0] and N[1:0] inputs to reduce component count in the application of the chip. The serial interface centers on a twelve bit shift register. The shift register shifts once per rising edge of the S_CLOCK input. The serial input S_DATA must meet setup and hold timing as specified in the AC Characteristics section of this document. The configuration latches will capture the value of the shift register on the HIGH–to–LOW edge of the S_LOAD input. See the programming section for more information. The TEST output reflects various internal node values, and is controlled by the T[2:0] bits in the serial data stream. See the programming section for more information. The PWR_DOWN pin, when asserted, will synchronously divide the FOUT by 16. The power down sequence is clocked by the PLL reference clock, thereby causing the frequency reduction to happen relatively slowly. Upon de–assertion of the PWR_DOWN pin, the FOUT input will step back up to its programmed frequency in four discrete increments. 1/97 Motorola, Inc. 1997 1 REV 3 MC12439 VCC FOUT 25 24 FOUT GND 23 22 VCC 21 TEST GND 20 19 S_CLOCK 26 18 N[1] S_DATA 27 17 N[0] N[1:0] Output Division S_LOAD 28 16 NC PLL–VCC 1 15 XTAL_SEL 00 01 10 11 2 4 8 1 PWR_DOWN 2 14 M[6] FREF_EXT 3 13 M[5] XTAL1 4 12 M[4] 5 XTAL2 6 7 8 OE P_LOAD M[0] 9 10 11 M[1] M[2] M[3] Input 0 1 PWR_DOWN XTAL_SEL OE FOUT FREF_EXT Disabled FOUT/16 XTAL Enabled Figure 1. 28–Lead Pinout (Top View) PIN DESCRIPTIONS Pin Name Type Function Inputs XTAL1, XTAL2 — These pins form an oscillator when connected to an external series–resonant crystal. S_LOAD Int. Pulldown This pin loads the configuration latches with the contents of the shift registers. The latches will be transparent when this signal is HIGH, thus the data must be stable on the HIGH–to–LOW transition of S_LOAD for proper operation. S_DATA Int. Pulldown This pin acts as the data input to the serial configuration shift registers. S_CLOCK Int. Pulldown This pin serves to clock the serial configuration shift registers. Data from S_DATA is sampled on the rising edge. P_LOAD Int. Pullup This pin loads the configuration latches with the contents of the parallel inputs .The latches will be transparent when this signal is LOW, thus the parallel data must be stable on the LOW–to–HIGH transition of P_LOAD for proper operation. M[6:0] Int. Pullup These pins are used to configure the PLL loop divider. They are sampled on the LOW–to–HIGH transition of P_LOAD. M[6] is the MSB, M[0] is the LSB. N[1:0] Int. Pullup These pins are used to configure the output divider modulus. They are sampled on the LOW–to–HIGH transition of P_LOAD. OE Int. Pullup Active HIGH Output Enable. Outputs FOUT, FOUT — These differential positive–referenced ECL signals (PECL) are the output of the synthesizer. TEST — The function of this output is determined by the serial configuration bits T[2:0]. VCC — This is the positive supply for the chip, and is connected to +3.3V or 5.0V (VCC = PLL_VCC). PLL_VCC — This is the positive supply for the PLL, and should be as noise–free as possible for low–jitter operation. This supply is connected to +3.3V or 5.0V (VCC = PLL_VCC). GND — These pins are the negative supply for the chip and are normally all connected to ground. Power Other PWR_DOWN Int. Pulldown LVCMOS input that forces the FOUT output to synchronously reduce its frequency by a factor of 16. FREF_EXT Int. Pulldown LVCMOS input which can be used as the PLL reference frequency. XTAL_SEL Int. Pullup MOTOROLA LVCMOS input that selects between the XTAL and FREF_EXT PLL reference inputs. A HIGH selects the XTAL input. 2 TIMING SOLUTIONS BR1333 — Rev 6 MC12439 XTAL_SEL PWR_DOWN 15 +3.3 or 5.0V 2 PLL_VCC FREF_EXT 3 0 PHASE DETECTOR 1 4 16.66MHz +3.3 or 5.0V VCO VCC0 25 XTAL1 7–BIT DIV M COUNTER OSC 5 POWER DOWN 400–800 MHz XTAL2 24 23 DIV N (1, 2, 4, 8) 20 OE S_LOAD P_LOAD 6 LATCH S_CLOCK FOUT TEST LATCH 28 LATCH 7 0 S_DATA FOUT 27 1 0 7–BIT SR 1 2–BIT SR 3–BIT SR 26 VCC1 21 8 → 14 +3.3 or 5.0V 17, 18 22, 19 7 2 M[6:0] N[1:0] Figure 2. MC12439 Block Diagram PROGRAMMING INTERFACE FOUT = 16M, FOUT = 8M, FOUT = 4M and FOUT = 2M for 25 < M < 50 Programming the device amounts to properly configuring the internal dividers to produce the desired frequency at the outputs. The output frequency can by represented by this formula: FOUT = FXTAL x M ÷ N The user can identify the proper M and N values for the desired frequency from the above equations. The four output frequency ranges established by N are 400–800MHz, 200–400MHz, 100–200MHz and 50–100MHz respectively. From these ranges the user will establish the value of N required, then the value of M can be calculated based on the appropriate equation above. For example if an output frequency of 384MHz was desired the following steps would be taken to identify the appropriate M and N values. 384MHz falls within the frequency range set by an N value of 2 so N [1:0] = 00. For N = 2 FOUT = 8M and M = FOUT ÷ 8. Therefore M = 384 ÷ 8 = 48, so M[8:0] = 0110000. (1) Where FXTAL is the crystal frequency, M is the loop divider modulus, and N is the output divider modulus. Note that it is possible to select values of M such that the PLL is unable to achieve loop lock. To avoid this, always make sure that M is selected to be 25 ≤ M ≤ 50 for a 16MHz input reference. For input references other than 16MHz, the valid M values can be calculated from the valid VCO range of 400–800MHz. Assuming that a 16MHz reference frequency is used the above equation reduces to: For input reference frequencies other than 16MHz the set of appropriate equations can be deduced from equation 1. For computer applications another useful frequency base would be 16.666MHz. From this reference one can generate a family of output frequencies at multiples of the 33.333MHz PCI clock. As an example to generate a 533.333MHz clock FOUT = 16 x M ÷ N Substituting the four values for N (1, 2, 4, 8) yields: TIMING SOLUTIONS BR1333 — Rev 6 3 MOTOROLA MC12439 configuration stream. It is not configurable through the parallel interface. Although it is possible to select the node that represents FOUT, the CMOS output may not be able to toggle fast enough for some of the higher output frequencies. The T2, T1 and T0 control bits are preset to ‘000’ when P_LOAD is LOW so that the PECL FOUT outputs are as jitter–free as possible. Any active signal on the TEST output pin will have detrimental affects on the jitter of the PECL output pair. In normal operations, jitter specifications are only guaranteed if the TEST output is static. The serial configuration port can be used to select one of the alternate functions for this pin. from a 16.666MHz reference the following M and N values would be used: FOUT = 16.666 x M ÷ N Let N = 1, M = 533.333 ÷ 16.666 = 32 The value for M falls within the constraints set for PLL stability (400÷16.666 ≤ M ≤ 800÷16.666; 24 ≤ M ≤ 48), therefore N[1:0] = 11 and M[6:0} = 0100000. If the value for M fell outside of the valid range a different N value would be selected to try to move M in the appropriate direction. The M and N counters can be loaded either through a parallel or serial interface. The parallel interface is controlled via the P_LOAD signal such that a LOW to HIGH transition will latch the information present on the M[6:0] and N[1:0] inputs into the M and N counters. When the P_LOAD signal is LOW the input latches will be transparent and any changes on the M[6:0] and N[1:0] inputs will affect the FOUT output pair. To use the serial port the S_CLOCK signal samples the information on the S_DATA line and loads it into a 12 bit shift register. Note that the P_LOAD signal must be HIGH for the serial load operation to function. The Test register is loaded with the first three bits, the N register with the next two and the M register with the final eight bits of the data streeam on the S_DATA input. For each register the most significant bit is loaded first (T2, N1 and M6). A pulse on the S_LOAD pin after the shift register is fully loaded will transfer the divide values into the counters. The HIGH to LOW transition on the S_LOAD input will latch the new divide values into the counters. NO TAG illustrates the timing diagram for both a parallel and a serial load of the MC12439 synthesizer. Most of the signals available on the TEST output pin are useful only for performance verification of the MC12439 itself. However the PLL bypass mode may be of interest at the board level for functional debug. When T[2:0] is set to 110 the MC12439 is placed in PLL bypass mode. In this mode the S_CLOCK input is fed directly into the M and N dividers. The N divider drives the FOUT differential pair and the M counter drives the TEST output pin. In this mode the S_CLOCK input could be used for low speed board level functional test or debug. Bypassing the PLL and driving FOUT directly gives the user more control on the test clocks sent through the clock tree. NO TAG shows the functional setup of the PLL bypass mode. Because the S_CLOCK is a CMOS level the input frequency is limited to 250MHz or less. This means the fastest the FOUT pin can be toggled via the S_CLOCK is 250MHz as the minimum divide ratio of the N counter is 1. Note that the M counter output on the TEST output will not be a 50% duty cycle due to the way the divider is implemented. M[6:0] and N[1:0] are normally specified once at power–up through the parallel interface, and then possibly again through the serial interface. This approach allows the application to come up at one frequency and then change or fine–tune the clock as the ability to control the serial interface becomes available. The TEST output provides visibility for one of the several internal nodes as determined by the T[2:0] bits in the serial T2 T1 T0 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 TEST (Pin 20) SHIFT REGISTER OUT HIGH FREF M COUNTER OUT FOUT LOW PLL BYPASS FOUT/4 S_CLOCK S_DATA T2 S_LOAD First Bit M[6:0] N[1:0] T1 T0 N1 N0 M6 M5 M4 M3 M2 M1 M0 Last Bit M, N P_LOAD Figure 3. Timing Diagram MOTOROLA 4 TIMING SOLUTIONS BR1333 — Rev 6 MC12439 FREF VCO_CLK PLL 12439 MCNT 0 SCLOCK FOUT (VIA ENABLE GATE) N DIVIDE (1, 2, 4, 8) 1 SEL_CLK M COUNTER FDIV4 MCNT LOW FOUT MCNT FREF HIGH Shift Reg Out LATCH SDATA SHIFT REG 12–BIT Reset SLOAD T0 T1 T2 PLOADB 7 TEST MUX TEST 0 DECODE • T2=T1=1, T0=0: Test Mode • SCLOCK is selected, MCNT is on TEST output, SCLOCK DIVIDE BY N is on FOUT pin PLOADB acts as reset for test pin latch. When latch reset T2 data is shifted out TEST pin. Figure 4. Serial Test Clock Block Diagram DC CHARACTERISTICS (TA = 0 to 70°C; VCC = 3.3 to 5.0V ±5%) Symbol 1. 2. 3. 4. Characteristic VIH Input HIGH Voltage VIL Input LOW Voltage IIN Min Typ Max 2.0 Unit Condition V VCC = 3.3 to 5.0V 0.8 V VCC = 3.3 to 5.0V Input Current 1.0 mA IOH Output HIGH Current (Note 1.) (FOUT/FOUT Only) 50 VOH Output HIGH Voltage TEST VOL Output LOW Voltage TEST VOH Output HIGH Voltage FOUT FOUT VOL Output LOW Voltage FOUT FOUT ICC Power Supply Current 2.5 mA Continuous Current V IOH = –0.8mA, (Note 2.) 0.4 V IOL = 0.8mA, (Note 2.) 2.27 2.47 V VCC = 3.3V (Notes 3., 4.) 1.49 1.68 V VCC = 3.3V (Notes 3., 4.) 110 20 mA VCC PLL_VCC 90 15 Maximum IOH spec implies the device can drive 25Ω impedance with the PECL outputs. See Applications Information section for output level versus frequency information. Output levels will vary 1:1 with VCC variation. 50Ω to VCC – 2.0V pulldown. TIMING SOLUTIONS BR1333 — Rev 6 5 MOTOROLA MC12439 AC CHARACTERISTICS (TA = 0 to 70°C; VCC = 3.3 to 5.0V ±5%) Symbol FMAXI Characteristic Maximum Input Frequency Min Max Unit S_CLOCK Xtal Oscillator FREF_EXT 10 20 Note 5. MHz 10 10 VCO (Internal) FOUT 400 50 900 800 MHz 1 10 ms ±25 ±65 ps Condition FMAXO Maximum Output Frequency tLOCK Maximum PLL Lock Time tjitter Cycle–to–Cycle Jitter (Peak–to–Peak) (Note 6.) ts Setup Time S_DATA to S_CLOCK S_CLOCK to S_LOAD M, N to P_LOAD 20 20 20 ns th Hold Time S_DATA to S_CLOCK M, N to P_LOAD 20 20 ns tpwMIN Minimum Pulse Width S_LOAD P_LOAD 50 50 ns Note 7. tr, tf Output Rise/Fall Time ps Note 7. 300 800 N = 2,4,8; Note 7. N = 1; Note 7. 5. Maximum frequency on FREF_EXT is a function of the internal M counter limitations. The phase detector can handle up to 100MHz on the input, but the M counter must remain in the valid range of 25 ≤ M ≤ 50. See the programming section in this data sheet for more details. 6. See Applications Information section for additional information. 7. 50Ω to VCC – 2.0V pulldown. MOTOROLA 6 TIMING SOLUTIONS BR1333 — Rev 6 MC12439 APPLICATIONS INFORMATION Using the On–Board Crystal Oscillator The MC12439 features a fully integrated on–board crystal oscillator to minimize system implementation costs. The oscillator is a series resonant, multivibrator type design as opposed to the more common parallel resonant oscillator design. The series resonant design provides better stability and eliminates the need for large on chip capacitors. The oscillator is totally self contained so that the only external component required is the crystal. As the oscillator is somewhat sensitive to loading on its inputs the user is advised to mount the crystal as close to the MC12439 as possible to avoid any board level parasitics. To facilitate co–location surface mount crystals are recommended, but not required. be seen on a fully digital product. Analog circuitry is naturally susceptible to random noise, especially if this noise is seen on the power supply pins. The MC12439 provides separate power supplies for the digital ciruitry (VCC) and the internal PLL (PLL_VCC) of the device. The purpose of this design technique is to try and isolate the high switching noise digital outputs from the relatively sensitive internal analog phase–locked loop. In a controlled environment such as an evaluation board this level of isolation is sufficient. However, in a digital system environment where it is more difficult to minimize noise on the power supplies a second level of isolation may be required. The simplest form of isolation is a power supply filter on the PLL_VCC pin for the MC12439. Figure 5 illustrates a typical power supply filter scheme. The MC12439 is most susceptible to noise with spectral content in the 1KHz to 1MHz range. Therefore the filter should be designed to target this range. The key parameter that needs to be met in the final filter design is the DC voltage drop that will be seen between the VCC supply and the PLL_VCC pin of the MC12439. From the data sheet the IPLL_VCC current (the current sourced through the PLL_VCC pin) is typically 15mA (20mA maximum), assuming that a minimum of 3.0V must be maintained on the PLL_VCC pin very little DC voltage drop can be tolerated when a 3.3V VCC supply is used. The resistor shown in Figure 5 must have a resistance of 10–15Ω to meet the voltage drop criteria. The RC filter pictured will provide a broadband filter with approximately 100:1 attenuation for noise whose spectral content is above 20KHz. As the noise frequency crosses the series resonant point of an individual capacitor it’s overall impedance begins to look inductive and thus increases with increasing frequency. The parallel capacitor combination shown ensures that a low impedance path to ground exists for frequencies well above the bandwidth of the PLL. The oscillator circuit is a series resonant circuit and thus for optimum performance a series resonant crystal should be used. Unfortunately most crystals are characterized in a parallel resonant mode. Fortunately there is no physical difference between a series resonant and a parallel resonant crystal. The difference is purely in the way the devices are characterized. As a result a parallel resonant crystal can be used with the MC12439 with only a minor error in the desired frequency. A parallel resonant mode crystal used in a series resonant circuit will exhibit a frequency of oscillation a few hundred ppm lower than specified, a few hundred ppm translates to kHz inaccuracies. In a general computer application this level of inaccuracy is immaterial. Table 1 below specifies the performance requirements of the crystals to be used with the MC12439. Table 1. Crystal Specifications Parameter Value Crystal Cut Fundamental AT Cut Resonance Series Resonance* Frequency Tolerance ±75ppm at 25°C Frequency/Temperature Stability ±150pm 0 to 70°C Operating Range 0 to 70°C Shunt Capacitance 5–7pF Equivalent Series Resistance (ESR) 50 to 80Ω Correlation Drive Level 100µW Aging 5ppm/Yr (First 3 Years) 3.3V or 5.0V RS=10–15Ω PLL_VCC 22µF * See accompanying text for series versus parallel resonant discussion. VCC 0.01µF Power Supply Filtering The MC12439 is a mixed analog/digital product and as such it exhibits some sensitivities that would not necessarily TIMING SOLUTIONS BR1333 — Rev 6 0.01µF MC12439 Figure 5. Power Supply Filter 7 MOTOROLA MC12439 ensure a stable, jitter free interface between the crystal and the on–board oscillator. Although the MC12439 has several design features to minimize the susceptibility to power supply noise (isolated power and grounds and fully differential PLL) there still may be applications in which overall performance is being degraded due to system power supply noise. The power supply filter and bypass schemes discussed in this section should be adequate to eliminate power supply noise related problems in most designs. A higher level of attenuation can be acheived by replacing the resistor with an appropriate valued inductor. A 1000µH choke will show a significant impedance at 10KHz frequencies and above. Because of the current draw and the voltage that must be maintained on the PLL_VCC pin a low DC resistance inductor is required (less than 15Ω). Generally the resistor/capacitor filter will be cheaper, easier to implement and provide an adequate level of supply filtering. The MC12439 provides sub–nanosecond output edge rates and thus a good power supply bypassing scheme is a must. Figure 6 shows a representaive board layout for the MC12439. There exists many different potential board layouts and the one pictured is but one. The important aspect of the layout in Figure 6 is the low impedance connections between VCC and GND for the bypass capacitors. Combining good quality general purpose chip capacitors with good PCB layout techniques will produce effective capacitor resonances at frequencies adequate to supply the instantaneous switching current for the 12439 outputs. It is imperative that low inductance chip capacitors are used; it is equally important that the board layout does not introduce back all of the inductance saved by using the leadless capacitors. Thin interconnect traces between the capacitor and the power plane should be avoided and multiple large vias should be used to tie the capacitors to the buried power planes. Fat interconnect and large vias will help to minimize layout induced inductance and thus maximize the series resonant point of the bypass capacitors. ÉÉÉ ÉÉÉ ÉÉÉ ÉÉÉ C1 ÉÉ ÉÉ Jitter Performance of the MC12439 The MC12439 exhibits long term and cycle–to–cycle jitter which rivals that of SAW based oscillators. This jitter performance comes with the added flexibility one gets with a synthesizer over a fixed frequency oscillator. 25 RMS Jitter (ps) ÉÉÉ ÉÉÉ ÉÉÉ ÉÉÉ 500 600 700 800 VCO Frequency (MHz) Figure 7. RMS PLL Jitter versus VCO Frequency C1 NO TAG illustrates the RMS jitter performance of the MC12439 across its specified VCO frequency range. Note that the jitter is a function of both the output frequency as well as the VCO frequency, however the VCO frequency shows a much stronger dependence. The data presented has not been compensated for trigger jitter, this fact provides a measure of guardband to the reported data. In addition the data represents long term period jitter, the cycle–to–cycle jitter could not be measured to the level of accuracy required with available test equipment but certainly will be smaller than the long term period jitter. C2 R1 = 10–15Ω C1 = 0.01µF C2 = 22µF C3 = 0.1µF The most commonly specified jitter parameter is cycle–to–cycle jitter. Unfortunately with today’s high performance measurement equipment there is no way to measure this parameter for jitter performance in the class demonstrated by the MC12439. As a result different methods are used which approximate cycle–to–cycle jitter. The typical method of measuring the jitter is to accumulate a large number of cycles, create a histogram of the edge placements and record peak–to–peak as well as standard deviations of the jitter. Care must be taken that the measured edge is the edge immediately following the trigger edge. The oscilloscope cannot collect adjacent pulses, rather it collects pulses from a very large sample of pulses. It is safe to assume that collecting pulse information in this mode will produce period jitter values somewhat larger than if consecutive cycles (cycle–to–cycle jitter) were measured. All of the jitter data reported on the MC12439 was collected in this manner. ÉÉ ÉÉ = VCC = GND = Via Figure 6. PCB Board Layout for MC12439 Note the dotted lines circling the crystal oscillator connection to the device. The oscillator is a series resonant circuit and the voltage amplitude across the crystal is relatively small. It is imperative that no actively switching signals cross under the crystal as crosstalk energy coupled to these lines could significantly impact the jitter of the device. Special attention should be paid to the layout of the crystal to MOTOROLA 10 0 400 1 Xtal 15 5 R1 C3 N=2 N=4 N=8 20 8 TIMING SOLUTIONS BR1333 — Rev 6 MC12439 25 140 15 Peak–to–Peak Jitter (ps) RMS Jitter (ps) 20 6.25ps Reference 10 5 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 Spec Limit N=1 100 80 60 40 400 Output Frequency (MHz) 500 600 700 800 Output Frequency (MHz) Figure 8. RMS Jitter versus Output Frequency Figure 9. Peak–to–Peak Jitter versus Output Frequency NO TAG shows the jitter as a function of the output frequency. For the 12439 this information is probably of more importance. The flat line represents an RMS jitter value that corresponds to an 8 sigma ±25ps peak–to–peak long term period jitter. The graph shows that for output frequencies from 87.5 to 400MHz the jitter falls within the ±25ps peak–to–peak specification. The general trend is that as the output frequency is decreased the output edge jitter will increase. The jitter data presented should provide users with enough information to determine the effect on their overall timing budget. The jitter performance meets the needs of most system designs while adding the flexibility of frequency margining and field upgrades. These features are not available with a fixed frequency SAW oscillator. The jitter data from NO TAG and NO TAG do not include the performance of the 12439 when the output is in the divide by 1 mode. In divide by one mode the output signal is a digitally doubled version of the VCO output. The period of the outputs of the digital doubler is dependent on the duty cycle of the VCO output. Since the VCO output duty cycle cannot be guaranteed to be always 50% the resulting 12439 output in divide by one mode will be bimodal at times. Since a bimodal distribution cannot be acurately represented with an rms value, peak–to–peak values of jitter for the divide by one mode are presented. Output Voltage Swing vs Frequency In the divide by one mode the output rise and fall times will limit the peak to peak output voltage swing. For a 400MHz output the peak to peak swing of the 12439 output will be approximately 700mV. This swing will gradually degrade as the output frequency increases, at 800MHz the output swing will be reduced to approximately 500mV. For a worst case analysis it would be safe to assume that the 12439 output will always generate at least a 400mV output swing. Note that most high speed ECL receivers require only a few hundred millivolt input swings for reliable operation. As a result the output generated by the 12439 will, under all conditions, be sufficient for clocking standard ECL devices. Note that if a larger swing is desired the 12439 could drive a single gate ECLinPS Lite amplifier like the MC100LVEL16. The LVEL16 will speed up the output edge rates and produce a full swing ECL output at 800MHz. Figure 9 shows the peak–to–peak jitter of the 12439 output in divide by one mode as a function of output frequency. Notice that as with the other modes the jitter improves with increasing frequency. The ±65ps shown in the data sheet table represents a conservative value of jitter, especially for the higher vco, and thus output frequencies. TIMING SOLUTIONS BR1333 — Rev 6 120 9 MOTOROLA MC12439 OUTLINE DIMENSIONS FN SUFFIX PLASTIC PLCC PACKAGE CASE 776–02 ISSUE D 0.007 (0.180) B Y BRK –N – T L –M M U 0.007 (0.180) X G1 M S N T L –M S S N S D Z –L – –M – D W 28 V 1 C A 0.007 (0.180) M R 0.007 (0.180) M T L –M S T L –M S T L –M S N S S N S H 0.007 (0.180) M T L –M N S S K1 0.004 (0.100) G J –T – K SEATING PLANE F VIEW S G1 T L –M S N 0.007 (0.180) M T L –M S N S VIEW S S NOTES: 1. DATUMS –L–, –M–, AND –N– DETERMINED WHERE TOP OF LEAD SHOULDER EXITS PLASTIC BODY AT MOLD PARTING LINE. 2. DIM G1, TRUE POSITION TO BE MEASURED AT DATUM –T–, SEATING PLANE. 3. DIM R AND U DO NOT INCLUDE MOLD FLASH. ALLOWABLE MOLD FLASH IS 0.010 (0.250) PER SIDE. 4. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 5. CONTROLLING DIMENSION: INCH. 6. THE PACKAGE TOP MAY BE SMALLER THAN THE PACKAGE BOTTOM BY UP TO 0.012 (0.300). DIMENSIONS R AND U ARE DETERMINED AT THE OUTERMOST EXTREMES OF THE PLASTIC BODY EXCLUSIVE OF MOLD FLASH, TIE BAR BURRS, GATE BURRS AND INTERLEAD FLASH, BUT INCLUDING ANY MISMATCH BETWEEN THE TOP AND BOTTOM OF THE PLASTIC BODY. 7. DIMENSION H DOES NOT INCLUDE DAMBAR PROTRUSION OR INTRUSION. THE DAMBAR PROTRUSION(S) SHALL NOT CAUSE THE H DIMENSION TO BE GREATER THAN 0.037 (0.940). THE DAMBAR INTRUSION(S) SHALL NOT CAUSE THE H DIMENSION TO BE SMALLER THAN 0.025 (0.635). MOTOROLA N E S S VIEW D–D Z 0.010 (0.250) 0.010 (0.250) 10 DIM A B C E F G H J K R U V W X Y Z G1 K1 INCHES MIN MAX 0.485 0.495 0.485 0.495 0.165 0.180 0.090 0.110 0.013 0.019 0.050 BSC 0.026 0.032 0.020 — 0.025 — 0.450 0.456 0.450 0.456 0.042 0.048 0.042 0.048 0.042 0.056 — 0.020 2° 10° 0.410 0.430 0.040 — MILLIMETERS MIN MAX 12.32 12.57 12.32 12.57 4.20 4.57 2.29 2.79 0.33 0.48 1.27 BSC 0.66 0.81 0.51 — 0.64 — 11.43 11.58 11.43 11.58 1.07 1.21 1.07 1.21 1.07 1.42 — 0.50 2° 10° 10.42 10.92 1.02 — TIMING SOLUTIONS BR1333 — Rev 6 MC12439 Motorola reserves the right to make changes without further notice to any products herein. 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How to reach us: USA / EUROPE / Locations Not Listed: Motorola Literature Distribution; P.O. Box 5405; Denver, Colorado 80217. 303–675–2140 or 1–800–441–2447 JAPAN: Nippon Motorola Ltd.; Tatsumi–SPD–JLDC, 6F Seibu–Butsuryu–Center, 3–14–2 Tatsumi Koto–Ku, Tokyo 135, Japan. 81–3–3521–8315 Mfax: [email protected] – TOUCHTONE 602–244–6609 INTERNET: http://www.mot.com/sps/ ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park, 51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852–26629298 TIMING SOLUTIONS BR1333 — Rev 6 ◊ 11 *MC12439/D* MC12439/D MOTOROLA