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NBC12439 3.3 V/5 V Programmable PLL Synthesized Clock Generator
50 MHz to 800 MHz
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The NBC12439 is a general purpose, PLL based synthesized clock source. The VCO will operate over a frequency range of 400 MHz to 800 MHz. The VCO frequency is sent to the N-output divider, where it can be configured to provide division ratios of 1, 2, 4 or 8. The VCO and output frequency can be programmed using the parallel or serial interfaces to the configuration logic. The PLL loop filter is fully integrated and does not require any external components.
MARKING DIAGRAMS
1 28
NBC12439 PLCC-28 FN SUFFIX CASE 776 AWLYYWW
* * * * * * * * * * *
Best-in-Class Output Jitter Performance, 20 ps Peak-to-Peak 50 MHz to 800 MHz Programmable Differential PECL Outputs Fully Integrated Phase-Lock-Loop with Internal Loop Filter Parallel Interface for Programming Counter and Output Dividers During Power-Up Minimal Frequency Overshoot Serial 3-Wire Programming Interface Crystal Oscillator Interface Operating Range: VCC = 3.135 V to 5.25 V CMOS and TTL Compatible Control Inputs Pin Compatible with Motorola MC12439 Power-Down of PECL Outputs (B16)
NBC12439 LQFP-32 FA SUFFIX CASE 873A AWLYYWW 32 1 A WL YY WW = Assembly Location = Wafer Lot = Year = Work Week
ORDERING INFORMATION
Device NBC12439FN NBC12439FNR2 NBC12439FA NBC12439FAR2 Package PLCC-28 PLCC-28 LQFP-32 LQFP-32 Shipping 37 Units/Rail 500 Tape & Reel 250 Units/Tray 2000 Tape & Reel
(c) Semiconductor Components Industries, LLC, 2003
1
May, 2003 - Rev. 2
Publication Order Number: NBC12439/D
NBC12439
PWR_DOWN 2 FREF +3.3 or 5.0 V 1 PLL_VCC
B2 XTAL_SEL FREF_EXT 15 3 4 10-20MHz 5 OE S_LOAD P_LOAD 6 28 7
PHASE DETECTOR VCO
POWER DOWN VCC BN (1, 2, 4, 8) 21, 25 24 23
+3.3 or 5.0 V
XTAL1 OSC XTAL2
7-BIT B M COUNTER
B2
FOUT FOUT
400-800 MHz
20 LATCH LATCH
TEST
LATCH 0 1 0 1
S_DATA S_CLOCK
27 7- BIT SR 26
2- BIT SR
3- BIT SR
8 14 7 M[6:0]
17, 18 2 N[1:0]
22, 19
Table 1. Output Division
N [1:0] 00 01 10 11 Output Division 2 4 8 1
Table 2. XTAL_SEL and OE
Input PWR_DOWN XTAL_SEL OE 0 FOUT FREF_EXT Disabled 1 FOUT B 16 XTAL Enabled
Figure 1. NBC12439 Block Diagram (28-Lead PLCC)
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NBC12439
FOUT FOUT TEST
20
GND
25
24
23
22
21
19 18
S_CLOCK S_DATA S_LOAD PLL_VCC PWR_DOWN FREF_EXT XTAL1
GND
VCC
VCC
26
N[1] N[0] NC XTAL_SEL M[6] M[5] M[4]
27
17
28
16
1
15
2
14
3
13
4 5 6 7 8 9 10 11
12
M[0]
M[1]
M[2] TEST
26
XTAL2
Figure 2. 28-Lead PLCC (Top View)
FOUT
FOUT
P_LOAD
GND
32
31
30
29
28
27
GND
25 24 23 22 21 20 19 18 17
VCC
VCC
VCC
M[3] N/C N[1] N[0] NC XTAL_SEL M[6] M[5] M[4]
S_CLOCK S_DATA S_LOAD PLL_VCC PLL_VCC PWR_DOWN FREF_EXT XTAL1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
OE
M[0]
M[1]
M[2]
XTAL2
P_LOAD
M[3]
Figure 3. 32-Lead LQFP (Top View)
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N/C
OE
NBC12439
The following gives a brief description of the functionality of the NBC12439 Inputs and Outputs. Unless explicitly stated, all inputs are CMOS/TTL compatible with either pull-up or pulldown resistors. The PECL outputs are capable of driving two series terminated 50 W transmission lines on the incident edge.
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Pin Name Function Description INPUTS XTAL1, XTAL2 S_LOAD* Crystal Inputs CMOS/TTL Serial Latch Input (Internal Pulldown Resistor) CMOS/TTL Serial Data Input (Internal Pulldown Resistor) CMOS/TTL Serial Clock Input (Internal Pulldown Resistor) CMOS/TTL Parallel Latch Input (Internal Pullup Resistor) These pins form an oscillator when connected to an external series-resonant crystal. 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. This pin acts as the data input to the serial configuration shift registers. This pin serves to clock the serial configuration shift registers. Data from S_DATA is sampled on the rising edge. This pin loads the configuration latches with the contents of the parallel inputs .The latches will be transparent when this signal is LOW; therefore, the parallel data must be stable on the LOW-to-HIGH transition of P_LOAD for proper operation. These pins are used to configure the PLL loop divider. They are sampled on the LOW-to-HIGH transition of P_LOAD. M[8] is the MSB, M[0] is the LSB. These pins are used to configure the output divider modulus. They are sampled on the LOW-to-HIGH transition of P_LOAD. Active HIGH Output Enable. The Enable is synchronous to eliminate possibility of runt pulse generation on the FOUT output. This pin can be used as the PLL Reference This pin selects between the crystal and the FREF_EXT source for the PLL reference signal. A HIGH selects the crystal input. PWR_DOWN forces the FOUT outputs to synchronously reduce frequency by a factor of 16. S_DATA* S_CLOCK* P_LOAD** M[6:0]** N[1:0]** OE** FREF_EXT* XTAL_SEL** PWR_DOWN OUTPUTS FOUT, FOUT TEST POWER VCC PLL_VCC GND Positive Supply for the Logic Positive Supply for the PLL Negative Power Supply The positive supply for the internal logic and output buffer of the chip, and is connected to +3.3 V or +5.0 V. This is the positive supply for the PLL and is connected to +3.3 V or +5.0 V. These pins are the negative supply for the chip and are normally all connected to ground. PECL Differential Outputs CMOS/TTL Output These differential, positive-referenced ECL signals (PECL) are the outputs of the synthesizer. The function of this output is determined by the serial configuration bits T[2:0]. CMOS/TTL PLL Loop Divider Inputs (Internal Pullup Resistor) CMOS/TTL Output Divider Inputs (Internal Pullup Resistor) CMOS/TTL Output Enable Input (Internal Pullup Resistor) CMOS/TTL Input (Internal Pulldown Resistor) CMOS/TTL Input (Internal Pullup Resistor) CMOS/TTL Input (Internal Pulldown Resistor) * When left Open, these inputs will default LOW. ** When left Open, these inputs will default HIGH.
PIN FUNCTION DESCRIPTION
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NBC12439
ATTRIBUTES
Characteristics Internal Input Pulldown Resistor Internal Input Pullup Resistor ESD Protection Human Body Model Machine Model Charged Device Model PLCC LQFP Oxygen Index: 28 to 34 Value 75 kW 37.5 kW > 2 kV > 150 V > 1 kV Level 1 Level 2
Moisture Sensitivity (Note 1) Flammability Rating Transistor Count Meets or exceeds JEDEC Spec EIA/JESD78 IC Latchup Test 1. For additional information, see Application Note AND8003/D.
UL 94 V-0 @ 0.125 in 2269
MAXIMUM RATINGS (Note 2)
Symbol VCC VI Iout TA Tstg qJA qJC qJA qJC Tsol Positive Supply Input Voltage Output Current Operating Temperature Range Storage Temperature Range Thermal Resistance (Junction to Ambient) Thermal Resistance (Junction to Case) Thermal Resistance (Junction to Ambient) Thermal Resistance (Junction to Case) Wave Solder Parameter Condition 1 GND = 0 V GND = 0 V Continuous Surge 0 LFPM 500 LFPM std bd 0 LFPM 500 LFPM std bd < 3 sec @ 248C VI VCC 28 PLCC 28 PLCC 28 PLCC 32 LQFP 32 LQFP 32 LQFP Condition 2 Rating 6 6 50 100 0 to +70 -65 to +150 63.5 43.5 22 to 26 80 55 12 to 17 265 Units V V mA mA C C C/W C/W C/W C/W C/W C/W C
2. Maximum Ratings are those values beyond which device damage may occur.
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NBC12439
DC CHARACTERISTICS (VCC = 3.3 V 5%)
0C Symbol VIH LVCMOS/ LVTTL VIL LVCMOS/ LVTTL IIN VOH VOL VOH PECL VOL PECL ICC Characteristic Input HIGH Voltage Condition VCC = 3.3 V Min 2.0 Typ Max Min 2.0 25C Typ Max Min 2.0 70C Typ Max Unit V
Input LOW Voltage
VCC = 3.3 V
-
-
0.8
-
-
0.8
-
-
0.8
V
Input Current Output HIGH Voltage TEST Output LOW Voltage TEST Output HIGH Voltage FOUT FOUT Output LOW Voltage FOUT FOUT Power Supply Current VCC PLL_VCC IOH = -0.8 mA IOL = 0.8 mA VCC = 3.3 V (Notes 3, 4) VCC = 3.3 V (Notes 3, 4)
2.5 2.155
-
1.0 0.4 2.405
2.5 2.155
-
1.0 0.4 2.405
2.5 2.155
-
1.0 0.4 2.405
mA V V V
1.355
-
1.675
1.355
-
1.675
1.355
-
1.675
V
44 19
56 23
80 28
44 19
58 23
80 28
44 19
61 23
80 28
mA mA
3. FOUT/FOUT output levels will vary 1:1 with VCC variation. 4. FOUT/FOUT outputs are terminated through a 50 W resistor to VCC - 2.0 volts.
DC CHARACTERISTICS (VCC = 5.0 V 5%)
0C Symbol VIH CMOS/ TTL VIL CMOS/ TTL IIN VOH VOL VOH PECL VOL PECL ICC Characteristic Input HIGH Voltage Condition VCC = 5.0 V Min 2.0 Typ Max Min 2.0 25C Typ Max Min 2.0 70C Typ Max Unit V
Input LOW Voltage
VCC = 5.0 V
-
-
0.8
-
-
0.8
-
-
0.8
V
Input Current Output HIGH Voltage TEST Output LOW Voltage TEST Output HIGH Voltage FOUT FOUT Output LOW Voltage FOUT FOUT Power Supply Current VCC PLL_VCC IOH = -0.8 mA IOL = 0.8 mA VCC = 5.0 V (Notes 5, 6) VCC = 5.0 V (Notes 5, 6)
2.5 3.855
-
1.0 0.4 4.105
2.5 3.855
-
1.0 0.4 4.105
2.5 3.855
-
1.0 0.4 4.105
mA V V V
3.055
-
3.305
3.055
-
3.305
3.055
-
3.305
V
47 19
58 24
85 28
47 19
60 24
85 28
47 19
64 24
85 28
mA mA
5. FOUT/FOUT output levels will vary 1:1 with VCC variation. 6. FOUT/FOUT outputs are terminated through a 50 W resistor to VCC - 2.0 volts.
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NBC12439
AC CHARACTERISTICS (VCC = 3.135 V to 5.25 V 5%; TA = 0 to 70C) (Note 8)
Symbol FMAXI Characteristic Maximum Input Frequency S_CLOCK Xtal Oscillator FREF_EXT VCO (Internal) FOUT (Note 7) Condition Min 10 10 400 50 (Note 10) 1000 Cycles 20 20 20 20 20 20 50 50 47.5 FOUT 20%-80% 175 Max 10 20 Note 9 800 800 10 "20 52.5 425 Unit MHz
FMAXO tLOCK tjitter ts
Maximum Output Frequency Maximum PLL Lock Time
MHz ms ps ns
Cycle-to-Cycle Jitter (Peak-to-Peak) Setup Time
S_DATA to S_CLOCK S_CLOCK to S_LOAD M, N to P_LOAD S_DATA to S_CLOCK S_CLOCK to S_LOAD M, N to P_LOAD S_LOAD P_LOAD
th
Hold Time
ns
tpwMIN DCO tr, tf
Minimum Pulse Width Output Duty Cycle Output Rise/Fall
ns % ps
7. 10 MHz is the maximum frequency to load the feedback divide registers. S_CLOCK can be switched at higher frequencies when used as a test clock in TEST_MODE 6. 8. FOUT/FOUT outputs are terminated through a 50 W resistor to VCC - 2.0 V. 9. Maximum frequency on FREF_EXT is a function of setting the appropriate M counter value, 25 MHz v M v 50 MHz, for the VCO to operate within the valid range of 400 MHz v fVCO v 800 MHz. The internal phase detector can handle up to 100 MHz on its input. 10. See applications information section.
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NBC12439
FUNCTIONAL DESCRIPTION The internal oscillator uses the external quartz crystal as the basis of its frequency reference. The output of the reference oscillator is divided by 16 before being sent to the phase detector. With a 2 MHz crystal, this provides a reference frequency of 8 MHz. Although this data sheet illustrates functionality only for a 16 MHz crystal, Table 3, any crystal in the 10-20 MHz range can be used, Table 5. The VCO within the PLL operates over a range of 400 to 800 MHz. Its output is scaled by a divider, M 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 the loop filter 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 N 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 the 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 into 50 W to VCC-2.0 V. The positive reference for the output driver and the internal logic is separated from the power supply for the phase-locked loop to minimize noise induced jitter. 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 upon 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 logic is implemented with a fourteen bit shift register scheme. The 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. With P_LOAD held high, 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.
Table 3. Programming VCO Frequency Function Table with 16 MHz Crystal
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VCO Frequency (MHz) 400 416 432 448 * * * 64 32 16 8 4 2 1 M Count 25 26 27 28 * * * M6 0 0 0 0 * * * M5 0 0 0 0 * * * M4 1 1 1 1 * * * M3 1 1 1 1 * * * M2 0 0 0 1 * * * M1 0 1 1 0 * * * M0 1 0 1 0 * * * 752 768 784 800 47 48 49 50 0 0 0 0 1 1 1 1 0 1 1 1 1 0 0 0 1 0 0 0 1 0 0 1 1 0 1 0
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NBC12439
PROGRAMMING INTERFACE Programming the NBC12439 is accomplished by properly configuring the internal dividers to produce the desired frequency at the outputs. The output frequency can by represented by this formula:
FOUT + (FXTAL B 2) 2M B N
(eq. 1)
The input frequency and the selection of the feedback divider M is limited by the VCO frequency range and fXTAL. M must be configured to match the VCO frequency range of 400 to 800 MHz in order to achieve stable PLL operation.
M min + fVCOmin B FXTAL and
(eq. 4) (eq. 5)
This can be simplified to:
FOUT + FXTALxM B N
(eq. 2)
M max + fVCOmax B FXTAL
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 16 MHz input reference. See Table 5. Assuming that a 16 MHz reference frequency is used the above equation reduces to:
FOUT + 16M B N
(eq. 3)
Substituting the four values for N (1, 2, 4, 8) yields:
Table 4. Programmable Output Divider Function Table
N1 1 0 0 1
N0 1 0 1 0
N Divider B1 B2 B4 B8
FOUT
Output Frequency Range (MHz)* 400-800 200-400 100-200 50-100
M
16 8 4 2
M M M
*For crystal frequency of 16 MHz.
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- 800 MHz, 200- 400 MHz, 100- 200 MHz and 50- 100 MHz, respectively. From these ranges, the user will establish the value of N required. The value of M can then be calculated based on equation 1. For example, if an output frequency of 384 MHz was desired, the following steps would be taken to identify the appropriate M and N values. 384 MHz falls within the frequency range set by an N value of 2; thus, N [1:0] = 00. For N = 2, FOUT = 8M and M = FOUT B 8. Therefore, M = 384 B 8 = 48, so M[6:0] = 0110000. Following this same procedure, a user can generate a selected frequency. The size of the programmable frequency steps of FOUT will be equal to FXTAL / N. For input reference frequencies other than 16 MHz, see Table 5, which shows the usable VCO frequency and M divider range.
The value for M falls within the constraints set for PLL stability. If the value for M fell outside of the valid range, a different N value would be selected 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 nine bits of the data stream on the S_DATA input. For each register, the most significant bit is loaded first (T2, N1, and M6). The HIGH to LOW transition on the S_LOAD input will latch the new divide values into the counters. A pulse on the S_LOAD pin after the shift register is fully loaded will transfer the divide values into the counters. Figures 4 and 5 illustrate the timing diagram for both a parallel and a serial load of the NBC12439 synthesizer. M[6:0] and N[1:0] are normally specified after power-up through the parallel interface, and then possibly, fine tuned again through the serial interface. This approach allows the application to ramp 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 configuration stream. It is not configurable through the parallel interface. 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.
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NBC12439
Table 5. NBC12439 Frequency Operating Range
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M 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 VCO Frequency (MHz) Range for a Crystal Frequency (MHz) of: M[6:0] 10 12 14 16 0010100 0010101 0010110 0010111 0011000 0011001 400 0011010 416 0011011 432 0011100 448 0011101 406 464 0011110 420 480 0011111 434 496 0100000 448 512 0100001 462 528 0100010 408 476 544 0100011 420 490 560 0100100 432 504 576 0100101 444 518 592 0100110 456 532 608 0100111 468 546 624 0101000 400 480 560 640 0101001 410 492 574 656 0101010 420 504 588 672 0101011 430 516 602 688 0101100 440 528 616 704 0101101 450 540 630 720 0101110 460 552 644 736 0101111 470 564 658 752 0110000 480 576 672 768 0110001 490 588 686 784 0110010 500 600 700 800 0110011 510 612 714 0110100 520 624 728 0110101 530 636 742 0110110 540 648 756 0110111 550 660 770 0111000 560 672 784 0111001 570 684 798 0111010 580 696 0111011 590 708 0111100 600 720 0111101 610 732 0111110 620 744 0111111 630 756 1000000 640 768 1000001 650 780 1000010 660 792 1000011 670 1000100 680 1000101 690 1000110 700 1000111 710 1001000 720 1001001 730 1001010 740 1001011 750 1001100 760 1001101 770 1001110 780 1001111 790 1010000 800 Output Frequency (MHz) for fXTAL = 16 MHz and for N = 18 414 432 450 468 486 504 522 540 558 576 594 612 630 648 666 684 702 720 738 756 774 792 20 400 420 440 460 480 500 520 540 560 580 600 620 640 660 680 700 720 740 760 780 800
B1
B2
B4
B8
400 416 432 448 464 480 496 512 528 544 560 576 592 608 624 640 656 672 688 704 720 736 752 768 784 800
200 208 216 224 232 240 248 256 264 272 280 288 296 304 312 320 328 336 344 352 360 368 376 384 392 400
100 104 108 112 116 120 124 128 132 136 140 144 148 152 156 160 164 168 172 176 180 184 188 192 196 200
50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86 88 90 92 94 96 98 100
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NBC12439
Most of the signals available on the TEST output pin are useful only for performance verification of the NBC12439 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 NBC12439 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. Figure 6 shows the functional setup of the PLL bypass mode. Because the S_CLOCK is a CMOS level the input frequency is limited to 250 MHz or less. This means the fastest the FOUT pin can be toggled via the S_CLOCK is 250 MHz 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.
T2 0 0 0 0 1 1 1 1 T1 0 0 1 1 0 0 1 1 T0 0 1 0 1 0 1 0 1 TEST OUTPUT SHIFT REGISTER OUT HIGH FREF M COUNTER OUT FOUT LOW PLL BYPASS FOUT B 4
M[8:0] N[1:0] P_LOAD
M, N
Figure 4. Parallel Interface Timing Diagram
S_CLOCK
S_DATA
T2 T1 First Bit
T0
N1
N0
M6
M5
M4
M3
M2
M1
M0 Last Bit
S_LOAD
Figure 5. Serial Interface Timing Diagram
FREF_EXT MCNT SCLOCK M COUNTER PLL 12439
VCO_CLK 0 1 SEL_CLK FDIV4 MCNT LOW FOUT MCNT FREF HIGH NB (1, 2, 4, 8) FOUT (VIA ENABLE GATE)
7 TEST MUX 0 TEST
LATCH SDATA Reset SHIFT REG T0 12- BIT T1 T2 SLOAD PLOAD DECODE
T2=T1=1, T0=0: Test Mode SCLOCK is selected, MCNT is on TEST output, SCLOCK B N is on FOUT pin. PLOAD acts as reset for test pin latch. When latch reset, T2 data is shifted out TEST pin.
* *
Figure 6. Serial Test Clock Block Diagram
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NBC12439
APPLICATIONS INFORMATION
Using the On-Board Crystal Oscillator Power Supply Filtering
The NBC12439 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 NBC12439 as possible to avoid any board level parasitics. To facilitate co-location, surface mount crystals are recommended, but not required. Because the series resonant design is affected by capacitive loading on the crystal terminals, loading variation introduced by crystals from different vendors could be a potential issue. For crystals with a higher shunt capacitance, it may be required to place a resistance across the terminals to suppress the third harmonic. Although typically not required, it is a good idea to layout the PCB with the provision of adding this external resistor. The resistor value will typically be between 500 W and 1 KW. 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 NBC12439 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 inaccuracy). Table 6 below specifies the performance requirements of the crystals to be used with the NBC12439.
Table 6. Crystal Specifications
Parameter Crystal Cut Resonance Frequency Tolerance Frequency/Temperature Stability Operating Range Shunt Capacitance Equivalent Series Resistance (ESR) Correlation Drive Level Aging Value Fundamental AT Cut Series Resonance* 75 ppm at 25C 150 ppm 0 to 70C 0 to 70C 5-7 pF 50 to 80 W 100 mW 5 ppm/Yr (First 3 Years)
The NBC12439 is a mixed analog/digital product and as such, it exhibits some sensitivities that would not necessarily 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 NBC12439 provides separate power supplies for the digital circuitry (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 of the 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 NBC12439. Figure 7 illustrates a typical power supply filter scheme. The NBC12439 is most susceptible to noise with spectral content in the 1 KHz to 1 MHz 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 NBC12439. From the data sheet, the PLL_VCC current (the current sourced through the PLL_VCC pin) is typically 23 mA (28 mA maximum). Assuming that a minimum of 2.8 V must be maintained on the PLL_VCC pin, very little DC voltage drop can be tolerated when a 3.3 V VCC supply is used. The resistor shown in Figure 7 must have a resistance of 10-15 W 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 20 KHz. 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.
* See accompanying text for series versus parallel resonant discussion.
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NBC12439
3.3 V or 5.0 V 3.3 V or 5.0 V
RS = 10-15 W PLL_VCC NBC12439 VCC 0.01 mF 22 mF 0.01 mF
L=1000 mH R=15 W
Figure 7. Power Supply Filter
A higher level of attenuation can be achieved by replacing the resistor with an appropriate valued inductor. Figure 7 shows a 1000 mH choke. This value choke will show a significant impedance at 10 KHz 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 15 W). Generally, the
resistor/capacitor filter will be cheaper, easier to implement, and provide an adequate level of supply filtering. The NBC12439 provides sub-nanosecond output edge rates and therefore a good power supply bypassing scheme is a must. Figure 8 shows a representative board layout for the NBC12439. There exists many different potential board layouts and the one pictured is but one. The important aspect of the layout in Figure 8 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 NBC12439 outputs. It is imperative that low inductance chip capacitors are used. It is equally important that the board layout not introduce any 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.
C1
R1
1 C3 C2 R1 = 10-15 W C1 = 0.01 mF C2 = 22 mF C3 = 0.1 mF Xtal
Figure 8. PCB Board Layout for NBC12439 (28 PLCC)
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 ensure a stable, jitter free interface between the crystal and the on-board oscillator. Note the provisions for
placing a resistor across the crystal oscillator terminals as discussed in the crystal oscillator section of this data sheet. Although the NBC12439 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.
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EE EE
EEE EEE EEE EEE
C1 = VCC = GND = Via
EEE EEE EEE EEE
EE EE
NBC12439
Jitter Performance of the NBC12439
Jitter is a common parameter associated with clock generation and distribution. Clock jitter can be defined as the deviation in a clock's output transition from its ideal position. Cycle-to-Cycle Jitter (short-term) is the period variation between adjacent periods over a defined number of observed cycles. The number of cycles observed is application dependent but the JEDEC specification is 1000 cycles. See Figure 9.
T0
T1 TJITTER(cycle- cycle) = T1 - T0
Figure 9. Cycle-to-Cycle Jitter
Random Peak-to-Peak Jitter is the difference between the highest and lowest acquired value and is represented as the width of the Gaussian base. See Figure 10.
RMS or one Sigma Jitter
Time* *1,000 - 10,000 Cycles
Typical Gaussian Distribution
Figure 10. Random Peak-to-Peak and RMS Jitter
There are different ways to measure jitter and often they are confused with one another. An earlier method of measuring jitter is to look at the timing signal with an oscilloscope and observe the variations in period-to-period or cycle-to-cycle. If the scope is set up to trigger on every rising or falling edge, set to infinite persistence mode and allowed to trace sufficient cycles, it is possible to determine the maximum and minimum periods of the timing signal. Digital scopes can 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. These scopes can also store a finite number of period durations and post-processing software can analyze the data to find the maximum and minimum periods. Recent hardware and software developments have resulted in advanced jitter measurement techniques. The Tektronix TDS-series oscilloscopes have superb jitter analysis capabilities on non-contiguous clocks with their histogram and statistics capabilities. The Tektronix TDSJIT2/3 Jitter Analysis software provides many key timing parameter measurements and will extend that capability by making jitter measurements on contiguous clock and data cycles from single-shot acquisitions. M1 by Amherst was used as well and both test methods correlated. These test processes can be correlated to earlier test methods and are more accurate. All of the jitter data reported on the NBC12439 was collected in this manner. Figure 11 shows the RMS jitter performance as a function of the VCO frequency range. The general trend is that as the VCO frequency is increased, the RMS output jitter will decrease. Figure 12 illustrates the RMS jitter performance versus the output frequency. Note 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. Long-Term Period Jitter is the maximum jitter observed at the end of a period's edge when compared to the position of the perfect reference clock's edge and is specified by the number of cycles over which the jitter is measured. The number of cycles used to look for the maximum jitter varies by application but the JEDEC spec is 10,000 observed cycles. The NBC12439 exhibits long term and cycle-to-cycle jitter, which rivals that of SAW based oscillators. This jitter performance comes with the added flexibility associated with a synthesizer over a fixed frequency oscillator. 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.
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Peak-to-Peak Jitter
Jitter Amplitude
NBC12439
25 25
20 RMS JITTER (ps) 600 700 800 RMS JITTER (ps)
20
15
15
10
N=8
10
N=4
5 N=1 0 400 N=2 500 VCO FREQUENCY (MHz)
5 0 100 200 300 400 500 600 700 800 OUTPUT FREQUENCY (MHz)
Figure 11. Cycle-to-Cycle RMS Jitter vs. VCO Frequency
Figure 12. Cycle-to-Cycle RMS Jitter vs. Output Frequency
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NBC12439
S_DATA
S_CLOCK tHOLD
tSET- UP
Figure 13. Set-Up and Hold
S_DATA tHOLD
S_LOAD
tSET- UP
Figure 14. Set-Up and Hold
M[8:0]
N[1:0]
P_LOAD tSET- UP tHOLD
Figure 15. Set-Up and Hold
FOUT
FOUT Pulse Width tPERIOD DCO + tpw tPERIOD
Figure 16. Output Duty Cycle
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NBC12439
FOUT Driver Device FOUT 50 W 50 W D
D Receiver Device
V TT V TT = V CC - 2.0 V
Figure 17. Typical Termination for Output Driver and Device Evaluation (See Application Note AND8020 - Termination of ECL Logic Devices.)
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NBC12439
PACKAGE DIMENSIONS
PLCC-28 FN SUFFIX PLASTIC PLCC PACKAGE CASE 776-02 ISSUE E
B -NY BRK U D Z -L-M0.007 (0.180)
M
T L-M
M
S
N
S S
0.007 (0.180)
T L-M
N
S
W
28 1
D
X VIEW D-D
G1
0.010 (0.250)
S
T L-M
S
N
S
V
A Z R C
0.007 (0.180) 0.007 (0.180)
M M
T L-M T L-M
S S
N N
S S
H
0.007 (0.180)
M
T L-M
S
N
S
E G G1 0.010 (0.250)
S
K1 0.004 (0.100)
J
-TVIEW S
SEATING PLANE
K F VIEW S 0.007 (0.180)
M
T L-M
S
N
S
T L-M
S
N
S
NOTES: 1. DATUMS -L-, -M-, AND -N- DETERMINED WHERE TOP OF LEAD SHOULDER EXITS PLASTIC BODY AT MOLD PARTING LINE. 2. DIMENSION G1, TRUE POSITION TO BE MEASURED AT DATUM -T-, SEATING PLANE. 3. DIMENSIONS 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).
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 ---
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NBC12439
PACKAGE DIMENSIONS
LQFP-32 FA SUFFIX PLASTIC LQFP PACKAGE CASE 873A-02 ISSUE A
-T-, -U-, -ZAE P V AE
8 17
A
32
4X 25
A1
0.20 (0.008) AB T-U Z
1
-TB B1 DETAIL Y
-U-
V1
DETAIL Y
BASE METAL
9
-Z9 S1 S
F
D
8X
M_ R
J
G -ABSEATING PLANE
DETAIL AD CE
SECTION AE-AE
-AC0.10 (0.004) AC 0.250 (0.010) H W X DETAIL AD K Q_
GAUGE PLANE
NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DATUM PLANE -AB- IS LOCATED AT BOTTOM OF LEAD AND IS COINCIDENT WITH THE LEAD WHERE THE LEAD EXITS THE PLASTIC BODY AT THE BOTTOM OF THE PARTING LINE. 4. DATUMS -T-, -U-, AND -Z- TO BE DETERMINED AT DATUM PLANE -AB-. 5. DIMENSIONS S AND V TO BE DETERMINED AT SEATING PLANE -AC-. 6. DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. ALLOWABLE PROTRUSION IS 0.250 (0.010) PER SIDE. DIMENSIONS A AND B DO INCLUDE MOLD MISMATCH AND ARE DETERMINED AT DATUM PLANE -AB-. 7. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. DAMBAR PROTRUSION SHALL NOT CAUSE THE D DIMENSION TO EXCEED 0.520 (0.020). 8. MINIMUM SOLDER PLATE THICKNESS SHALL BE 0.0076 (0.0003). 9. EXACT SHAPE OF EACH CORNER MAY VARY FROM DEPICTION.
DIM A A1 B B1 C D E F G H J K M N P Q R S S1 V V1 W X
MILLIMETERS MIN MAX 7.000 BSC 3.500 BSC 7.000 BSC 3.500 BSC 1.400 1.600 0.300 0.450 1.350 1.450 0.300 0.400 0.800 BSC 0.050 0.150 0.090 0.200 0.500 0.700 12_ REF 0.090 0.160 0.400 BSC 1_ 5_ 0.150 0.250 9.000 BSC 4.500 BSC 9.000 BSC 4.500 BSC 0.200 REF 1.000 REF
INCHES MIN MAX 0.276 BSC 0.138 BSC 0.276 BSC 0.138 BSC 0.055 0.063 0.012 0.018 0.053 0.057 0.012 0.016 0.031 BSC 0.002 0.006 0.004 0.008 0.020 0.028 12_ REF 0.004 0.006 0.016 BSC 1_ 5_ 0.006 0.010 0.354 BSC 0.177 BSC 0.354 BSC 0.177 BSC 0.008 REF 0.039 REF
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0.20 (0.008)
0.20 (0.008) AC T-U Z
M
4X
EE EE EE EE
N
AC T-U Z
NBC12439
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer.
PUBLICATION ORDERING INFORMATION
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NBC12439/D

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