LTC6930-X.XX 32.768kHz to 8.192MHz Precision Power Oscillators FEATURES n n n n n n n n n n DESCRIPTION Frequency Error <0.09% Max at 25C Start-Up Time <110s at All Frequencies 1.7V to 5.5V Single Supply Operation 105A Typical Supply Current at 32kHz, V+ = 3V 490A Typical Supply Current at 8MHz, V+ = 3V Typical RMS Period Jitter <0.15% at V+ = 3V No External Components to Set Frequency 5 Options Cover 32.768kHz to 8.192MHz: LTC6930-4.19: 4.194304MHz / N LTC6930-5.00: 5.000000MHz / N LTC6930-7.37: 7.372800MHz / N LTC6930-8.00: 8.000000MHz / N LTC6930-8.19: 8.192000MHz / N Where N = 1, 2, 4, 8, 16, 32, 64, 128 (N Determined by State of DIVA, DIVB, DIVC Pins) -40C to 125C Operating Temperature Range Tiny 2mm x 3mm DFN or MS8 Package APPLICATIONS n n n n Digitally Controlled Oscillator Microprocessor Clock Power Supply Clock Portable and Battery Operated Devices The LTC(R)6930 series is a family of very low power precision silicon oscillators with a frequency error less than 0.09%. For each oscillator, the user can select one of 8 frequencies between 32.768kHz and 8.192MHz. Based on a fixed master oscillator frequency, internal frequency dividers between 1 and 128 provide the 8 different frequencies. The LTC6930 requires no external components other than power supply bypass capacitors. Requiring only a single 1.7V to 5.5V supply enables operation from a single Li-Ion cell or 2 AA alkaline cells. The LTC6930 features a proprietary control architecture that allows for ultralow power operation while maintaining industry leading accuracy and jitter specifications. The exceptionally fast start-up time, combined with the low power consumption, is ideal for battery operated applications with frequent power-up cycles. Any frequency from 32.768kHz to 8.192MHz can be provided by the factory. Minimum order sizes apply for custom frequencies. Please consult LTC Marketing for details. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6342817, 6614313. TYPICAL APPLICATION 4MHz Micropower Clock Generator Typical Frequency Error Distribution 70 V+ = 1.7V TO 5.5V IS = 325A AT 3VDC TA = 25C V+ = 3V 60 DIV = 0 1045 UNITS 50 0.1F V+ DIVA OUT LTC6930-8.00 DIVB 4MHz 40 30 20 DIVC GND UNITS V+ 10 GND 6930 TA01a 0 -0.10 -0.05 0 0.05 FREQUENCY ERROR (%) 0.10 6930 TA01b 6930fd 1 LTC6930-X.XX ABSOLUTE MAXIMUM RATINGS (Note 1) Total Supply Voltage (V+ to GND).............................................. -0.3V to 6V Any Input Pin to GND (DIV Pins).......................................-0.3V to V+ + 0.3V Operating Temperature Range (Note 2) LTC6930C............................................. -40C to 85C LTC6930I.............................................. -40C to 85C LTC6930H........................................... -40C to 125C Specified Temperature Range (Note 3) LTC6930C................................................. 0C to 70C LTC6930I.............................................. -40C to 85C LTC6930H........................................... -40C to 125C Storage Temperature Range.................... -65C to 150C Lead Temperature (Soldering, 10 sec)................... 300C PIN CONFIGURATION TOP VIEW V+ 1 GND 2 DIVA 3 TOP VIEW 8 V+ 9 V+ GND DIVA DIVB 7 OUT 6 GND 5 DIVC DIVB 4 1 2 3 4 8 7 6 5 V+ OUT GND DIVC MS8 PACKAGE 8-LEAD PLASTIC MSOP DCB PACKAGE 8-LEAD (2mm x 3mm) PLASTIC DFN TJMAX = 125C, JA = 64C/W EXPOSED PAD (PIN 9) MUST BE SOLDERED TO GND TJMAX = 150C, JA = 300C/W (SINGLE-LAYER BOARD) ORDER INFORMATION Lead Free Finish TAPE AND REEL (MINI) TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION LTC6930CDCB-4.19#TRMPBF LTC6930CDCB-4.19#TRPBF LCKT 8-Lead (2mm x 3mm) Plastic DFN 0C to 70C LTC6930IDCB-4.19#TRMPBF LTC6930IDCB-4.19#TRPBF 8-Lead (2mm x 3mm) Plastic DFN -40C to 85C LCKT TEMPERATURE RANGE LTC6930HDCB-4.19#TRMPBF LTC6930HDCB-4.19#TRPBF LCKT 8-Lead (2mm x 3mm) Plastic DFN -40C to 125C LTC6930CDCB-5.00#TRMPBF LTC6930CDCB-5.00#TRPBF LCKV 8-Lead (2mm x 3mm) Plastic DFN 0C to 70C LTC6930IDCB-5.00#TRMPBF LTC6930IDCB-5.00#TRPBF 8-Lead (2mm x 3mm) Plastic DFN -40C to 85C LCKV LTC6930HDCB-5.00#TRMPBF LTC6930HDCB-5.00#TRPBF LCKV 8-Lead (2mm x 3mm) Plastic DFN -40C to 125C LTC6930CDCB-7.37#TRMPBF LTC6930CDCB-7.37#TRPBF LCKW 8-Lead (2mm x 3mm) Plastic DFN 0C to 70C LTC6930IDCB-7.37#TRMPBF LTC6930IDCB-7.37#TRPBF 8-Lead (2mm x 3mm) Plastic DFN -40C to 85C LCKW LTC6930HDCB-7.37#TRMPBF LTC6930HDCB-7.37#TRPBF LCKW 8-Lead (2mm x 3mm) Plastic DFN -40C to 125C LTC6930CDCB-8.00#TRMPBF LTC6930CDCB-8.00#TRPBF LCKX 8-Lead (2mm x 3mm) Plastic DFN 0C to 70C LTC6930IDCB-8.00#TRMPBF LTC6930IDCB-8.00#TRPBF 8-Lead (2mm x 3mm) Plastic DFN -40C to 85C LCKX LTC6930HDCB-8.00#TRMPBF LTC6930HDCB-8.00#TRPBF LCKX 8-Lead (2mm x 3mm) Plastic DFN -40C to 125C LTC6930CDCB-8.19#TRMPBF LTC6930CDCB-8.19#TRPBF LCKY 8-Lead (2mm x 3mm) Plastic DFN 0C to 70C LTC6930IDCB-8.19#TRMPBF LTC6930IDCB-8.19#TRPBF 8-Lead (2mm x 3mm) Plastic DFN -40C to 85C LCKY LTC6930HDCB-8.19#TRMPBF LTC6930HDCB-8.19#TRPBF LCKY 8-Lead (2mm x 3mm) Plastic DFN -40C to 125C TRM = 500 pieces. 6930fd 2 LTC6930-X.XX ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC6930CMS8-4.19#PBF LTC6930CMS8-4.19#TRPBF LTCKZ 8-Lead Plastic MSOP 0C to 70C LTC6930IMS8-4.19#PBF LTC6930IMS8-4.19#TRPBF LTCKZ 8-Lead Plastic MSOP -40C to 85C LTC6930HMS8-4.19#PBF LTC6930HMS8-4.19#TRPBF LTCKZ 8-Lead Plastic MSOP -40C to 125C LTC6930CMS8-5.00#PBF LTC6930CMS8-5.00#TRPBF LTCLB 8-Lead Plastic MSOP 0C to 70C LTC6930IMS8-5.00#PBF LTC6930IMS8-5.00#TRPBF LTCLB 8-Lead Plastic MSOP -40C to 85C LTC6930HMS8-5.00#PBF LTC6930HMS8-5.00#TRPBF LTCLB 8-Lead Plastic MSOP -40C to 125C LTC6930CMS8-7.37#PBF LTC6930CMS8-7.37#TRPBF LTCLC 8-Lead Plastic MSOP 0C to 70C LTC6930IMS8-7.37#PBF LTC6930IMS8-7.37#TRPBF LTCLC 8-Lead Plastic MSOP -40C to 85C LTC6930HMS8-7.37#PBF LTC6930HMS8-7.37#TRPBF LTCLC 8-Lead Plastic MSOP -40C to 125C LTC6930CMS8-8.00#PBF LTC6930CMS8-8.00#TRPBF LTCLD 8-Lead Plastic MSOP 0C to 70C LTC6930IMS8-8.00#PBF LTC6930IMS8-8.00#TRPBF LTCLD 8-Lead Plastic MSOP -40C to 85C LTC6930HMS8-8.00#PBF LTC6930HMS8-8.00#TRPBF LTCLD 8-Lead Plastic MSOP -40C to 125C LTC6930CMS8-8.19#PBF LTC6930CMS8-8.19#TRPBF LTCLF 8-Lead Plastic MSOP 0C to 70C LTC6930IMS8-8.19#PBF LTC6930IMS8-8.19#TRPBF LTCLF 8-Lead Plastic MSOP -40C to 85C LTC6930HMS8-8.19#PBF LTC6930HMS8-8.19#TRPBF LTCLF 8-Lead Plastic MSOP -40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges.*Temperature grades are identified by a label on the shipping container. Consult LTC Marketing for information on lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ AC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. Unless otherwise noted, specifications apply over the full range of operating supply voltage and frequency output: V+ = 1.7V to 5.5V and all DIV settings with CLOAD = 5pF, RLOAD = . SYMBOL fi f PARAMETER CONDITIONS Initial Frequency Accuracy DIVA = DIVB = DIVC = 0, TA Frequency Accuracy (Note 4) V+ = 3V - 3.6V f/T Frequency Drift Over Temperature f/V Frequency Drift Over Supply Long-Term Frequency Stability MIN = 25C, V+ = 3V TYP MAX UNITS 0.08 0.09 % LTC6930C LTC6930I LTC6930H l l l 0.1 0.1 0.1 0.45 0.65 1 % % % V+ = 2V - 3.6V LTC6930C LTC6930I LTC6930H l l l 0.1 0.1 0.1 0.52 0.65 1.1 % % % V+ = 1.7V - 5.5V LTC6930C LTC6930I LTC6930H l l l 0.1 0.1 0.1 0.8 0.95 1.3 % % % MS8 Package DCB Package l l 0.0001 0.001 %/C %/C l 0.07 %/V l 30 (Note 5) ppm/kHr 6930fd 3 LTC6930-X.XX AC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. Unless otherwise noted, specifications apply over the full range of operating supply voltage and frequency output: V+ = 1.7V to 5.5V and all DIV settings with CLOAD = 5pF, RLOAD = . SYMBOL PARAMETER CONDITIONS RMS Period Jitter DIVA = DIVB = DIVC = 0, V+ = 3V LTC6930-4.19 (4.194304MHz) MIN TYP MAX 320 1.7 225 1.2 180 0.97 130 0.8 130 0.8 LTC6930-5.00 (5.000000MHz) LTC6930-7.37 (7.372800MHz) LTC6930-8.00 (8.000000MHz) LTC6930-8.19 (8.192000MHz) UNITS ps RMS nsP-P ps RMS nsP-P ps RMS nsP-P ps RMS nsP-P ps RMS nsP-P DC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. Unless otherwise noted, specifications apply over the full range of operating supply voltage and frequency output: V+ = 1.7V to 5.5V and all DIV settings with CLOAD = 5pF, RLOAD = . SYMBOL VS IS,DC IS,DC VIH PARAMETER Supply Voltage Applied Between V+ and GND V+ Combined Supply Current V+ Combined Supply Current Minimum High Level Input Voltage, All Digital Input Pins CONDITIONS l MIN 1.7 TYP MAX 5.5 UNITS V LTC6930-4.19 DIVA = DIVB = DIVC = 0, V+ = 1.7V DIVA = DIVB = DIVC = 0, V+ = 3V DIVA = DIVB = DIVC = 0, V+ = 5.5V DIVA = DIVB = DIVC = 1, V+ = 1.7V DIVA = DIVB = DIVC = 1, V+ = 3V DIVA = DIVB = DIVC = 1, V+ = 5.5V l l l l l l 170 260 490 80 105 130 290 420 750 160 190 355 A A A A A A LTC6930-5.00 DIVA = DIVB = DIVC = 0, V+ = 1.7V DIVA = DIVB = DIVC = 0, V+ = 3V DIVA = DIVB = DIVC = 0, V+ = 5.5V DIVA = DIVB = DIVC = 1, V+ = 1.7V DIVA = DIVB = DIVC = 1, V+ = 3V DIVA = DIVB = DIVC = 1, V+ = 5.5V l l l l l l 201 307 579 95 124 154 430 570 960 176 212 375 A A A A A A LTC6930-7.37 DIVA = DIVB = DIVC = 0, V+ = 1.7V DIVA = DIVB = DIVC = 0, V+ = 3V DIVA = DIVB = DIVC = 0, V+ = 5.5V DIVA = DIVB = DIVC = 1, V+ = 1.7V DIVA = DIVB = DIVC = 1, V+ = 3V DIVA = DIVB = DIVC = 1, V+ = 5.5V l l l l l l 296 453 853 139 183 226 480 660 1310 220 273 440 A A A A A A LTC6930-8.00 DIVA = DIVB = DIVC = 0, V+ = 1.7V DIVA = DIVB = DIVC = 0, V+ = 3V DIVA = DIVB = DIVC = 0, V+ = 5.5V DIVA = DIVB = DIVC = 1, V+ = 1.7V DIVA = DIVB = DIVC = 1, V+ = 3V DIVA = DIVB = DIVC = 1, V+ = 5.5V l l l l l l 321 491 926 151 198 246 520 740 1380 240 295 475 A A A A A A LTC6930-8.19 DIVA = DIVB = DIVC = 0, V+ = 1.7V DIVA = DIVB = DIVC = 0, V+ = 3V DIVA = DIVB = DIVC = 0, V+ = 5.5V DIVA = DIVB = DIVC = 1, V+ = 1.7V DIVA = DIVB = DIVC = 1, V+ = 3V DIVA = DIVB = DIVC = 1, V+ = 5.5V l l l l l l 310 500 880 150 190 210 490 760 1400 270 325 540 A A A A A A l 1.25 1.4 V 6930fd 4 LTC6930-X.XX DC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. Unless otherwise noted, specifications apply over the full range of operating supply voltage and frequency output: V+ = 1.7V to 5.5V and all DIV settings with CLOAD = 5pF, RLOAD = . SYMBOL VIL IIN ROUT VOH VOL PARAMETER Maximum Low Level Input Voltage, All Digital Input Pins Digital Input Leakage Current, All Digital Input Pins Output Resistance High Level Output Voltage Low Level Output Voltage CONDITIONS l 0 < VIN < V+ MIN 0.7 TYP 1.25 1 l OUT Pin, V+ = 3V DIVA = DIVB = DIVC = 0, No Load V+ = 5.5V V+ = 3V V+ = 2V V+ = 1.7V DIVA = DIVB = DIVC = 0, 1k Load to GND V+ = 5.5V V+ = 3V V+ = 2V V+ = 1.7V DIVA = DIVB = DIVC = 0, No Load V+ = 5.5V V+ = 3V V+ = 2V V+ = 1.7V DIVA = DIVB = DIVC = 0, 1k Load to V+ V+ = 5.5V V+ = 3V V+ = 2V V+ = 1.7V MAX UNITS V A 40 l l l 5.4 2.9 1.8 5.5 3 2 1.7 V V V V l l l 5 2.6 1.5 5.2 2.7 1.6 1.5 V V V V l l l 0 0 0 0 0.1 0.1 0.1 V V V V l l l 0.3 0.3 0.3 0.3 0.7 0.5 0.35 V V V V TIMING CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. Unless otherwise noted, specifications apply over the full range of operating supply voltage and frequency output: V+ = 1.7V to 5.5V and fOUT = 32.768kHz to 8.192MHz with CLOAD = 5pF, RLOAD = . SYMBOL PARAMETER trf Output Rise/Fall Time (10% to 90%) V+ = 3V CONDITIONS MIN DCY Duty Cycle DDIV DIV to FOUT Delay Edge of DIV Signal to 1st Accurate Output Cycle Power On Delay V+ > 1.7V to 1st Accurate Output Cycle DIVA = DIVB = DIVC = 0 DIVA or DIVB or DIVC 0 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: LTC6930C is guaranteed functional over the operating range of -40C to 85C. Note 3: The LTC6930C is guaranteed to meet specified performance from 0C to 70C. The LTC6930C is designed, characterized and expected to meet specified performance from -40C to 85C but is not tested or QA sampled at these temperatures. The LTC6930I is guaranteed to meet specified performance from -40C to 85C. The LTC6930H is guaranteed to meet specified performance from -40C to 125C. Note 4: Frequency accuracy and frequency drift are defined as deviation from the nominal frequency or the nominal frequency divided by the integer set through the DIV pins for each part. The nominal frequency for MAX 3 DIVA = DIVB = DIVC = 0; V+ = 2V to 5.5V DPON TYP l l l 35 35 48 50 50 50 ns 65 70 52 1 l UNITS % % % Cycle 110 s the LTC6930 family of parts are defined as follows: LTC6930-4.19 fNOM = 4.194304MHz LTC6930-5.00 fNOM = 5.000000MHz LTC6930-7.37 fNOM = 7.372800MHz LTC6930-8.00 fNOM = 8.000000MHz LTC6930-8.19 fNOM = 8.192000MHz Note 5: Long-term drift of silicon oscillators is primarily due to the movement of ions and impurities within the silicon and is tested at 30C under otherwise nominal operating conditions. Long-term drift is specified as ppm/kHr due to the typically non-linear nature of the drift. To calculate drift for a set time period, translate that time into thousands of hours, take the square root and multiply by the typical drift number. For instance, a year is 8.77kHr and would yield a drift of 89ppm at 30ppm/kHr. Drift without power applied to the device may be approximated as 1/10th of the drift with power, or 3ppm/kHr for a 30ppm/kHr device. 6930fd 5 LTC6930-X.XX TYPICAL PERFORMANCE CHARACTERISTICS Frequency Error vs Temperature, MS8 Package 0.25 0.60 TA = 25C 0.20 Frequency Error vs Temperature, DFN Package 0.60 V+ = 3V 8.19MHz 0.10 0.05 4.19MHz 0 -0.05 -0.10 -0.15 V+ = 3V 0.40 FREQUENCY ERROR (%) 0.40 0.15 FREQUENCY ERROR (%) 0.20 0 -0.20 -0.40 0.20 0 -0.20 -0.40 -0.20 -0.25 1.7 -0.60 -45 -25 -5 2.7 3.7 4.7 SUPPLY VOLTAGE (V) 15 35 55 75 TEMPERATURE (C) 95 115 125 4216 G01 2000 TA = 25C 8.192MHz, 1.7V 8.192MHz, 3V 200 100 4.194MHz, 3V 1 4.194MHz, 1.7V 10 DIV SETTING (LOG) 100 1400 1200 POWER SUPPLY CURRENT (A) 1000 DIVIDE = 1 900 TA = 25C DIV = 16 DIV = 32 DIV = 64 DIV = 128 1000 800 600 800 600 500 300 200 100 6930 G04 0 10 20 30 40 50 LOAD CAPACITANCE (pF) 60 4.194MHz 400 200 0 8.192MHz 700 400 0 1.7 2.2 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 4216 G05 Typical Supply Current vs Temperature 700 Typical Supply Current vs Supply Voltage V+ = 3V TA = 25C DIV = 1 DIV = 2 DIV = 4 DIV = 8 1600 SUPPLY CURRENT (A) SUPPLY CURRENT (A) 500 0 LTC6930-8.19 1800 300 95 115 125 4216 G03 Typical Supply Current vs Load Capacitance 400 15 35 55 75 TEMPERATURE (C) 4216 G02 Typical Supply Current vs DIV Setting 600 -0.60 -45 -25 -5 SUPPLY CURRENT (A) FREQUENCY ERROR (%, NORMALIZED TO 3V) Typical Frequency Error vs Supply Voltage 5.2 4216 G06 Typical Output Spectrum, 8MHz Typical Output Waveform, 8MHz CLOAD = 5pF 600 500 400 3V, 8.192MHz 0.45V/DIV 10dB/DIV 3V, 4.19MHz 300 200 100 0 -45 400kHz/DIV 1.7V, 32kHz 5 55 TEMPERATURE (C) 105 6930 G08 LTC6930-8.00 CLOAD = 12pF 40ns/DIV 6930 G09 4216 G07 6930fd 6 LTC6930-X.XX TYPICAL PERFORMANCE CHARACTERISTICS Typical Jitter vs Supply in Divide by 1 Mode 0.30 Typical Period Jitter Histogram 400 TA = 25C LTC6930-8.19 0.25 0.12 8.192MHz JITTER (% RMS) 0.15 200 0.10 100 2.2 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 0 -450 5.2 -300 -150 0 150 PERIOD ERROR (ps) 300 4.194MHz 0.06 8.192MHz Typical Output Rise/Fall Time vs Supply Typical Output Resistance vs Supply Voltage 100 CLOAD = 5pF TA = 25C 4.0 OUTPUT RESISTANCE () 3.5 RISE TIME 3.0 2.5 2.0 FALL TIME 1.5 1.0 0.5 0 1.7 2.2 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 5.2 56 70 54 60 50 40 30 50 48 DIVIDE BY >1 44 42 4216 G13 5.2 4MHz, DIVIDE BY 1 46 10 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 8MHz, DIVIDE BY 1 52 20 2.2 40 1.7 2.2 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) Typical Frequency Error vs Time (Long-Term Drift) 10 5.2 4216 G15 4216 G14 Typical Frequency Settling from Power-Up 100 6930 G12 58 80 0 1.7 10 DIV SETTING (LOG) 60 TA = 25C 90 1 Typical Output Duty Cycle vs Supply and Divide Ratio DUTY CYCLE (%) 4.5 0 450 4216 G11 4216 G10 OUTPUT RISE/FALL TIME (ns) 0.08 0.02 0 1.7 Typical Output Waveform at DIV Pin Change 500 25 PARTS SHOWN 400 TA = 30C 5 0 DELTA FREQUENCY (ppm) FREQUENCY ERROR (%) 0.10 0.04 0.05 -5 -10 -15 -20 -25 -30 V+ = 3V TA = 25C 0.14 300 0.20 SAMPLES JITTER (% RMS) 4.194MHz Typical Jitter vs Divider Setting 0.16 V+ = 3V TA = 25C DIVIDE = 1 300 200 100 0 -100 -200 -300 400ns/DIV -400 0 50 100 150 TIME SINCE POWER APPLIED (s) 200 4216 G16 -500 0 500 1000 1500 2000 TIME (HOURS) 2500 6930 G18 3000 4216 G17 6930fd 7 LTC6930-X.XX PIN FUNCTIONS V+ (Pins 1, 8): Positive Supply Pins. Each supply pin should be bypassed directly to the neighboring GND pin with a 0.1F ceramic capacitor, and must be externally connected to the other V+ pin (see recommended layout). GND (Pins 2, 6): Ground Pins. Each should be connected to a low inductance ground plane and must be connected to the other GND pin and on the DFN package, Pin 9. DIVA, DIVB, DIVC (Pins 3, 4, 5): Output Prescaler. Selects divide ratio of master oscillator frequency used to generate the output. See frequency setting Table 1 for function. These are standard CMOS logic inputs with a typical threshold of 1.25V OUT (Pin 7): Oscillator Output. Drives up to 50pF capacitive or 1k resistive load (Refer to Supply Current vs Load Capacitance in Typical Performance Characteristics section). Typical series resistance is less than 80 at 1.7V and less than 40 at 3V supply. The output trace should be isolated as much as possible from Pin 1 and Pin 2. The OUT pin is held low during start-up, and remains free from glitches and runt pulses during DIV pin switching. Exposed Pad (Pin 9, DFN Only): The Exposed Pad must be soldered to a PCB plane connected to GND. APPLICATIONS INFORMATION Theory of Operation Output Driver and Loading The LTC6930 is an entirely self contained all silicon oscillator which consists of a master oscillator, a control loop and an output frequency divider. The master oscillator operates between 4.2MHz and 8.2MHz and is factory programmed. The master oscillator frequency is accurately maintained over temperature and environmental extremes by a proprietary switched capacitor feedback loop. The output of the LTC6930 is a low series resistance 40 CMOS driver with controlled rise/fall times to limit RF interference and power supply spikes generated by the output while preserving the ability to drive low impedance loads. Especially at high frequencies, the capacitive loading of the output of the LTC6930 may cause the majority of the power supply dissipation of the part. Each LTC6930 oscillator has an output frequency divider which is controlled via the DIVA, DIVB and DIVC inputs. The divider divides the master frequency by 2N, where N is an integer from 0 to 7 (divider ranges from 1 to 128). See Table 1 for the full range of frequencies covered by the LTC6930 family. The LTC6930 supply current is specified at an output load of 5pF, which is equivalent to two standard HC logic inputs. The portion of the power supply current needed to drive a capacitive load may be calculated as: The presence of two sets of supply pins and careful internal layout reduce interference between the oscillator output and the control loop. This allows the LTC6930 to provide a clean output frequency with very little deterministic jitter, even in cases of heavy output loading and noisy operating environments. The supply voltage of the LTC6930 is internally regulated to maintain a very low frequency drift over supply. ISUPPLY = CLOAD * VSWING * fOSC where CLOAD is the 5pF load capacitance, VSWING is the voltage swing, in this case up to 5.5V, and fOSC is the frequency of the oscillator output. Driving a 5.5V swing into a 5pF load at 8MHz takes an average of 220A. To calculate the portion of the supply current needed for a 50pF load, simply substitute 50pF for CLOAD in the same equation: 50pF * 5.5V * 8MHz = 2.2mA The majority of this power is expended during the rise and fall time of the output signal, not while it is in a steady 6930fd 8 LTC6930-X.XX APPLICATIONS INFORMATION state. The 2ns rise and fall times of the LTC6930 mean that the instantaneous power supply current required during the rise and fall portions of the waveform is much greater than the average. The instantaneous power supply current may be calculated by a similar formula: 1 IPEAK = CLOAD * VSWING * tr f where trf is the rise/fall time of the signal. In this case, 14mA spikes are generated by driving 5.5V into a 5pF load. Power is supplied to the output driver of the LTC6930 from the V+ and GND pins on each side of the output pin (Pins 6 and 8). Allowances must be made in the design to provide for output load related supply current spikes, especially in high accuracy applications. A 0.1F ceramic capacitor connected between V+ and GND (Pins 6 and 8) as close as possible to the device will decouple the rest of the circuit from spikes caused by powering a capacitive output load of up to 50pF. See Figure 1. C1 0.1F V+ OUT Start-Up Time The start-up time of the LTC6930 is typically 50s from the time that valid power is applied to the first output pulse. The output is held low for the first 50s to prevent any glitches, runt pulses, or invalid frequency output during start-up. Long-Term Drift Long-term stability of silicon oscillators is specified in ppm/kHr, which is typical of other silicon devices such as operational amplifiers and voltage references. Because drift in silicon-based oscillators is generated primarily by movement of ions in the silicon, most of the drift is accomplished early in the life of the device and the drift can be expected to level off in the long term. The ppm/kHr unit models this time variant decay. Crystal oscillators are often specified with drift measured in ppm/year because their drift mechanism is different. A comparison of various drift rates over a five year time period is shown in Figure 2. When calculating the amount of drift to be expected, it is important to consider the entire time in the calculation, because the relationship to time is not linear. The drift for C2 0.1F 0.045 0.040 GND 0.035 DRIFT (%) 0.030 GND 6930 F01 Figure 1. Recommended Layout 60ppm/kHr 0.025 0.020 0.015 30ppm/kHr 0.010 0.005 10ppm/kHr 0 Switching the DIV Pins The LTC6930 is designed to quickly and cleanly respond to the digital inputs. The output will respond to the DIV pins within a single clock cycle without introducing any sliver or runt pulses. 0 20 40 MONTHS 60 80 6930 F02 Figure 2. 5 Year Drift at Various Rates 6930fd 9 LTC6930-X.XX APPLICATIONS INFORMATION 5 years is not 5 times the drift for one year. A sample calculation for drift over 5 years at 30ppm/kHr is as follows: 5 years * 365.25 days/year * 24 hours/day = 43,830 hours = 43.830kHr 43.830kHr = 6.62kHr 6.62kHr * 30ppm/kHr = 0.0198% over 5 years. Drift calculations assume that the part is in continuous operation during the entire time period of the calculation. The movement of ions which results in drift is usually aided by electric fields in the operating parts, and the typical drift spec applies while the part is powered up. Conservative calculations would use a tenth of the drift specification for time when power is not applied to the part. Setting the Frequency The output frequency of the LTC6930 is chosen from the values in Table 1 and set using the DIV pins, as noted in the table. Master oscillator frequency is preset in the factory, and the DIV pins select an internal binary divider of up to 128. For example, if the desired oscillator output frequency is 2.5MHz, finding 2.5MHz in Table 1 shows that the LTC6930-5.00 should be ordered, having a master oscillator frequency of 5MHz, and a DIV value of [001] should be used. This would equate to grounding DIVC and DIVB, while connecting DIVA to the positive supply. Frequencies other than those shown in Table 1 may be requested. Table 1. Frequency Setting and Available Frequencies DIV Pin Settings [DIVC][DIVB][DIVA] LTC6930-4.19 /1 /2 /4 /8 /16 /32 /64 /128 000 001 010 011 100 101 110 111 524.288kHz 262.144kHz 131.072kHz 65.536kHz 32.768kHz 4.194304MHz 2.097152MHz 1.048576MHz LTC6930-5.00 5.000MHz 2.500MHz 1.250MHz 625.0kHz 312.5kHz 156.25kHz 78.125kHz 39.0625kHz LTC6930-7.37 7.3728MHz 3.6864MHz 1.8432MHz 921.6kHz 460.8kHz 230.4kHz 115.2kHz 57.6kHz LTC6930-8.00 8.000MHz 4.000MHz 2.000MHz 1000kHz 500.0kHz 250.0kHz 125.0kHz 62.5kHz LTC6930-8.19 8.192MHz 4.096MHz 2.048MHz 1024kHz 512.0kHz 256.0kHz 128.0kHz 64.0kHz 6930fd 10 LTC6930-X.XX PACKAGE DESCRIPTION DCB Package 8-Lead Plastic DFN (2mm x 3mm) (Reference LTC DWG # 05-08-1718 Rev A) 0.70 0.05 1.35 0.05 3.50 0.05 1.65 0.05 2.10 0.05 PACKAGE OUTLINE 0.25 0.05 0.45 BSC 1.35 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 2.00 0.10 (2 SIDES) R = 0.05 TYP R = 0.115 TYP 5 0.40 0.10 8 1.35 0.10 1.65 0.10 3.00 0.10 (2 SIDES) PIN 1 NOTCH R = 0.20 OR 0.25 x 45 CHAMFER PIN 1 BAR TOP MARK (SEE NOTE 6) (DCB8) DFN 0106 REV A 4 0.200 REF 1 0.23 0.05 0.45 BSC 0.75 0.05 1.35 REF 0.00 - 0.05 BOTTOM VIEW--EXPOSED PAD NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 6930fd 11 LTC6930-X.XX PACKAGE DESCRIPTION MS8 Package 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1660 Rev F) 3.00 0.102 (.118 .004) (NOTE 3) 0.889 0.127 (.035 .005) 5.23 (.206) MIN 0.254 (.010) 7 6 5 0.52 (.0205) REF 3.00 0.102 (.118 .004) (NOTE 4) 4.90 0.152 (.193 .006) DETAIL "A" 0 - 6 TYP GAUGE PLANE 3.20 - 3.45 (.126 - .136) 0.53 0.152 (.021 .006) DETAIL "A" 0.42 0.038 (.0165 .0015) TYP 8 0.65 (.0256) BSC 1 1.10 (.043) MAX 2 3 4 0.86 (.034) REF 0.18 (.007) RECOMMENDED SOLDER PAD LAYOUT NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX SEATING PLANE 0.22 - 0.38 (.009 - .015) TYP 0.65 (.0256) BSC 0.1016 0.0508 (.004 .002) MSOP (MS8) 0307 REV F 6930fd 12 LTC6930-X.XX REVISION HISTORY (Revision history begins at Rev C) REV DATE DESCRIPTION PAGE NUMBER C 1/11 Revised the option for LTC6930-7.37 under Features. 1 D 2/11 Added LTC6930CMS8-4.19 to the Order Information section. 3 6930fd Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 13 LTC6930-X.XX TYPICAL APPLICATION Dual, Matched, Digitally Programmable, Lowpass Filter, 2kHz to 256kHz VIN1 3.48k IN+ OUT 2 IN- V+ 3 2k 5V 1 1F VIN2 3.48k 2k 4 DIVA DIVB V - DIV/CLK IN+ OUT 2 IN- V+ 4 1 0.1F RX LTC1569-7 1 3 1F GND 2 3 4 GND RX LTC1569-7 V- DIV/CLK V+ V+ GND OUT DIVA GND LTC6930-8.192 DIVB DIVC 8 7 VOUT1 5V 0.1F 6 Amplitude Response 5 8 7 0 5V 0.1F 6 5 8 fCUTOFF 32kHz 128kHz -60 -100 fOSC 7 -40 fCUTOFF = 8kHz -80 5V 0.1F 1 10 100 FREQUENCY (kHz) 1000 6 5 6930 TA02 DIVC DIVC, DIVB, DIVA -20 VOUT2 GAIN (dB) 5V 000 001 010 011 100 101 110 111 256kHz 128kHz 64kHz 32kHz 16kHz 8kHz 4kHz 2kHz RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1799 1kHz to 33MHz ThinSOTTM Oscillator, Resistor Set Wide Frequency Range LTC6900 1kHz to 20MHz ThinSOT Oscillator, Resistor Set Low Power, Wide Frequency Range LTC6902 Multiphase Oscillator with Spread Spectrum Modulation 2-, 3- or 4-Phase Outputs LTC6903/LTC6904 1kHz to 68MHz Serial Port Programmable Oscillator 0.1% Frequency Resolution, I2C or SPI Interface LTC6905 17MHz to 170MHz ThinSOT Oscillator, Resistor Set High Frequency, 100s Start-Up, 7ps RMS Jitter LTC6905-XXX Fixed Frequency ThinSOT Oscillator Family, Up to 133MHz No Trim Components Required LTC6906 Micropower 10kHz to 1MHz ThinSOT Oscillator, Resistor Set 12A Supply Current at 100kHz, 0.65% Frequency Accuracy LTC6907 Micropower 40kHz to 4MHz ThinSOT Oscillator, Resistor Set 36A Supply Current at 400kHz, 0.65% Frequency Accuracy LTC6908 Multiphase Oscillator with Spread Spectrum Modulation 2 Outputs Shifted by Either 180 or 90 6930fd 14 Linear Technology Corporation LT 0211 REV D * PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear.com LINEAR TECHNOLOGY CORPORATION 2008