LTC6930-X.XX 32.768kHz to 8.192MHz Precision µPower Oscillators FEATURES DESCRIPTION n The LTC®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. n n n n n n n n n Frequency Error <0.09% Max at 25°C Startup Time <110μs at All Frequencies 1.7V to 5.5V Single Supply Operation 105μA Typical Supply Current at 32kHz, V+ = 3V 490μA 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: 7.373800MHz ÷ 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) –40°C to 125°C Operating Temperature Range Tiny 2mm × 3mm DFN or MS8 Package 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. APPLICATIONS n n n n The LTC6930 features a proprietary control architecture that allows for ultra-low 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. Digitally Controlled Oscillator Microprocessor Clock Power Supply Clock Portable and Battery Operated Devices L, LT, LTC and LTM are registered trademarks 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 V+ = 1.7V TO 5.5V 70 TA = 25°C V+ = 3V 60 DIV = 0 1045 UNITS 50 IS = 325μA AT 3VDC 0.1μF V+ UNITS V+ DIVA OUT LTC6930-8.00 DIVB 4MHz 40 30 20 DIVC GND 10 GND 0 –0.10 6930 TA01a –0.05 0 0.05 FREQUENCY ERROR (%) 0.10 6930 TA01b 6930fa 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 ............................................ –40°C to 85°C LTC6930I.............................................. –40°C to 85°C LTC6930H .......................................... –40°C to 125°C Specified Temperature Range (Note 3) LTC6930C ................................................ 0°C to 70°C LTC6930I.............................................. –40°C to 85°C LTC6930H .......................................... –40°C to 125°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) .................. 300°C PIN CONFIGURATION TOP VIEW V+ 1 GND 2 TOP VIEW 8 V+ 9 V+ 1 7 OUT DIVA 3 6 GND DIVB 4 5 DIVC GND 2 DIVA 3 DIVB 4 8 7 6 5 V+ OUT GND DIVC MS8 PACKAGE 8-LEAD PLASTIC MSOP TJMAX = 150°C, θJA = 300°C/W (SINGLE-LAYER BOARD) DCB PACKAGE 8-LEAD (2mm s 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 64°C/W EXPOSED PAD (PIN 9) IS V–, MUST BE SOLDERED TO PCB 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 × 3mm) Plastic DFN 0°C to 70°C LTC6930IDCB-4.19#TRMPBF LTC6930IDCB-4.19#TRPBF 8-Lead (2mm × 3mm) Plastic DFN –40°C to 85°C LCKT TEMPERATURE RANGE LTC6930HDCB-4.19#TRMPBF LTC6930HDCB-4.19#TRPBF LCKT 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LTC6930CDCB-5.00#TRMPBF LTC6930CDCB-5.00#TRPBF LCKV 8-Lead (2mm × 3mm) Plastic DFN 0°C to 70°C LTC6930IDCB-5.00#TRMPBF LTC6930IDCB-5.00#TRPBF 8-Lead (2mm × 3mm) Plastic DFN –40°C to 85°C LCKV LTC6930HDCB-5.00#TRMPBF LTC6930HDCB-5.00#TRPBF LCKV 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LTC6930CDCB-7.37#TRMPBF LTC6930CDCB-7.37#TRPBF LCKW 8-Lead (2mm × 3mm) Plastic DFN 0°C to 70°C LTC6930IDCB-7.37#TRMPBF LTC6930IDCB-7.37#TRPBF 8-Lead (2mm × 3mm) Plastic DFN –40°C to 85°C LCKW LTC6930HDCB-7.37#TRMPBF LTC6930HDCB-7.37#TRPBF LCKW 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LTC6930CDCB-8.00#TRMPBF LTC6930CDCB-8.00#TRPBF LCKX 8-Lead (2mm × 3mm) Plastic DFN 0°C to 70°C LTC6930IDCB-8.00#TRMPBF LTC6930IDCB-8.00#TRPBF 8-Lead (2mm × 3mm) Plastic DFN –40°C to 85°C LCKX LTC6930HDCB-8.00#TRMPBF LTC6930HDCB-8.00#TRPBF LCKX 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C LTC6930CDCB-8.19#TRMPBF LTC6930CDCB-8.19#TRPBF LCKY 8-Lead (2mm × 3mm) Plastic DFN 0°C to 70°C LTC6930IDCB-8.19#TRMPBF LTC6930IDCB-8.19#TRPBF 8-Lead (2mm × 3mm) Plastic DFN –40°C to 85°C LCKY LTC6930HDCB-8.19#TRMPBF LTC6930HDCB-8.19#TRPBF LCKY 8-Lead (2mm × 3mm) Plastic DFN –40°C to 125°C TRM = 500 pieces. 6930fa 2 LTC6930-X.XX ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC6930IMS8-4.19#PBF LTC6930IMS8-4.19#TRPBF LTCKZ LTC6930HMS8-4.19#PBF LTC6930HMS8-4.19#TRPBF LTCKZ 8-Lead Plastic MSOP –40°C to 125°C LTC6930CMS8-5.00#PBF LTC6930CMS8-5.00#TRPBF LTCLB 8-Lead Plastic MSOP 0°C to 70°C LTC6930IMS8-5.00#PBF LTC6930IMS8-5.00#TRPBF LTCLB 8-Lead Plastic MSOP –40°C to 85°C LTC6930HMS8-5.00#PBF LTC6930HMS8-5.00#TRPBF LTCLB 8-Lead Plastic MSOP –40°C to 125°C LTC6930CMS8-7.37#PBF LTC6930CMS8-7.37#TRPBF LTCLC 8-Lead Plastic MSOP 0°C to 70°C LTC6930IMS8-7.37#PBF LTC6930IMS8-7.37#TRPBF LTCLC 8-Lead Plastic MSOP –40°C to 85°C LTC6930HMS8-7.37#PBF LTC6930HMS8-7.37#TRPBF LTCLC 8-Lead Plastic MSOP –40°C to 125°C LTC6930CMS8-8.00#PBF LTC6930CMS8-8.00#TRPBF LTCLD 8-Lead Plastic MSOP 0°C to 70°C LTC6930IMS8-8.00#PBF LTC6930IMS8-8.00#TRPBF LTCLD 8-Lead Plastic MSOP –40°C to 85°C LTC6930HMS8-8.00#PBF LTC6930HMS8-8.00#TRPBF LTCLD 8-Lead Plastic MSOP –40°C to 125°C LTC6930CMS8-8.19#PBF LTC6930CMS8-8.19#TRPBF LTCLF 8-Lead Plastic MSOP 0°C to 70°C LTC6930IMS8-8.19#PBF LTC6930IMS8-8.19#TRPBF LTCLF 8-Lead Plastic MSOP –40°C to 85°C 8-Lead Plastic MSOP –40°C to 85°C LTC6930HMS8-8.19#PBF LTC6930HMS8-8.19#TRPBF LTCLF 8-Lead Plastic MSOP *Temperature grades are identified by a label on the shipping container. Consult LTC Marketing for parts specified with wider operating temperature ranges. 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/ –40°C to 125°C AC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. 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 Δfi Initial Frequency Accuracy DIVA = DIVB = DIVC = 0, TA = 25°C, V+ = 3V Frequency Accuracy (Note 4) V+ = 3V – 3.6V Δf Δf/ΔT Δf/ΔV Frequency Drift Over Temperature 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 l 0.07 l 30 Frequency Drift Over Supply Long-Term Frequency Stability MIN (Note 5) %/°C %/°C %/V ppm/√kHr 6930fa 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 = 25°C. 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 ps RMS nsP-P ps RMS nsP-P ps RMS nsP-P ps RMS nsP-P ps RMS nsP-P 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 DC ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. 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 μA μA μA μA μA μA 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 μA μA μA μA μA μA 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 μA μA μA μA μA μA 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 μA μA μA μA μA μA 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 μA μA μA μA μA μA l 1.25 1.4 V 6930fa 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 = 25°C. 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 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, 1kΩ 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, 1kΩ Load to V+ V+ = 5.5V V+ = 3V V+ = 2V V+ = 1.7V MAX ±1 UNITS V μA 40 Ω 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 = 25°C. 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 trf DCY PARAMETER CONDITIONS Output Rise/Fall Time (10% to 90%) V+ = 3V MIN Duty Cycle DIVA = DIVB = DIVC = 0; V+ = 2V to 5.5V DPON DIV to FOUT Delay Edge of DIV Signal to 1st Accurate Output Cycle Power On Delay V+ > 1.7V to 1st Accurate Output Cycle 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 –40°C to 85°C. Note 3: The LTC6930C is guaranteed to meet specified performance from 0°C to 70°C. The LTC6930C is designed, characterized and expected to meet specified performance from –40°C to 85°C but is not tested or QA sampled at these temperatures. The LTC6930I is guaranteed to meet specified performance from –40°C to 85°C. The LTC6930H is guaranteed to meet specified performance from –40°C to 125°C. 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 DIVA or DIVB or DIVC ≠ 0 DDIV TYP l l l 35 35 48 50 50 50 ns 65 70 52 1 l UNITS % % % Cycle 110 μs 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 30°C 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. 6930fa 5 LTC6930-X.XX TYPICAL PERFORMANCE CHARACTERISTICS 0.25 Frequency Error vs Temperature, MS8 Package 0.60 TA = 25°C Frequency Error vs Temperature, DFN Package 0.60 V+ = 3V V+ = 3V 0.20 8.19MHz 0.10 0.05 4.19MHz 0 –0.05 –0.10 –0.15 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 = 25°C LTC6930-8.19 1800 8.192MHz, 1.7V 8.192MHz, 3V 200 100 4.194MHz, 3V 4.194MHz, 1.7V 1200 POWER SUPPLY CURRENT (μA) DIVIDE = 1 900 TA = 25°C 800 DIV = 16 DIV = 32 DIV = 64 DIV = 128 1000 800 600 10 DIV SETTING (LOG) 600 500 300 200 100 0 6930 G04 10 20 30 40 50 LOAD CAPACITANCE (pF) 60 4.194MHz 400 200 100 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 1000 0 0 1 1400 Typical Supply Current vs Supply Voltage V+ = 3V TA = 25°C DIV = 1 DIV = 2 DIV = 4 DIV = 8 1600 SUPPLY CURRENT (μA) SUPPLY CURRENT (μA) 500 300 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 (μA) 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 3V, 8.192MHz 0.45V/DIV 10dB/DIV 400 3V, 4.19MHz 300 200 100 0 –45 400kHz/DIV 1.7V, 32kHz 5 55 TEMPERATURE (°C) 6930 G08 LTC6930-8.00 CLOAD = 12pF 40ns/DIV 6930 G09 105 4216 G07 6930fa 6 LTC6930-X.XX TYPICAL PERFORMANCE CHARACTERISTICS Typical Jitter vs Supply in Divide by 1 Mode 0.30 Typical Period Jitter Histogram 400 TA = 25°C LTC6930-8.19 0.25 V+ = 3V TA = 25°C DIVIDE = 1 0.12 8.192MHz JITTER (% RMS) 0.15 200 0.10 100 0.08 4.194MHz 0.06 8.192MHz 0.02 0 1.7 2.2 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 0 –450 5.2 0 –300 –150 0 150 PERIOD ERROR (ps) 300 Typical Output Rise/Fall Time vs Supply Typical Output Resistance vs Supply Voltage 100 CLOAD = 5pF TA = 25°C 4.0 OUTPUT RESISTANCE (Ω) 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) 1 10 DIV SETTING (LOG) 60 TA = 25°C 90 58 80 56 70 54 60 50 40 30 50 48 DIVIDE BY >1 44 42 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 4216 G13 4MHz, DIVIDE BY 1 46 10 2.2 8MHz, DIVIDE BY 1 52 20 0 1.7 5.2 40 1.7 5.2 2.2 2.7 3.2 3.7 4.2 4.7 SUPPLY VOLTAGE (V) 4216 G14 Typical Frequency Settling from Power-Up Typical Frequency Error vs Time (Long-Term Drift) 10 100 6930 G12 Typical Output Duty Cycle vs Supply and Divide Ratio DUTY CYCLE (%) 4.5 450 4216 G11 4216 G10 OUTPUT RISE/FALL TIME (ns) 0.10 0.04 0.05 5.2 4216 G15 Typical Output Waveform at DIV Pin Change 500 25 PARTS SHOWN 400 TA = 30°C DELTA FREQUENCY (ppm) 5 FREQUENCY ERROR (%) V+ = 3V TA = 25°C 0.14 300 0.20 SAMPLES JITTER (% RMS) 4.194MHz Typical Jitter vs Divider Setting 0.16 0 –5 –10 –15 –20 –25 300 200 100 0 –100 –200 –300 400ns/DIV –400 –30 6930 G18 –500 0 50 100 150 TIME SINCE POWER APPLIED (μs) 200 4216 G16 0 500 1000 1500 2000 TIME (HOURS) 2500 3000 4216 G17 6930fa 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 0.1μF 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 80Ω at 1.7V and less than 40Ω 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 startup, 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 40Ω 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. 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 220μA. To calculate the portion of the supply current needed for a 50pF load, simply substitute 50pF for CLOAD in the same equation: The supply voltage of the LTC6930 is internally regulated to maintain a very low frequency drift over supply. ISUPPLY = CLOAD • VSWING • fOSC 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 6930fa 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: IPEAK = CLOAD • VSWING • 1 trf Startup Time The startup time of the LTC6930 is typically 50μs from the time that valid power is applied to the first output pulse. The output is held low for the first 50μs to prevent any glitches, runt pulses, or invalid frequency output during startup. Long-Term Drift 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 0.1μF 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 0.1μF V+ OUT 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 5 years is not 5 times the drift for one year. A sample C2 0.1μF 0.045 GND 0.040 0.035 6930 F01 Figure 1. Recommended Layout 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. DRIFT (%) 0.030 GND 60ppm/√kHr 0.025 0.020 0.015 30ppm/√kHr 0.010 0.005 10ppm/√kHr 0 0 20 40 MONTHS 60 80 6930 F02 Figure 2. 5 Year Drift at Various Rates 6930fa 9 LTC6930-X.XX APPLICATIONS INFORMATION 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 = 6.62√kHr 6.62√kHr • 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 6930fa 10 LTC6930-X.XX PACKAGE DESCRIPTION DCB Package 8-Lead Plastic DFN (2mm × 3mm) (Reference LTC DWG # 05-08-1718 Rev A) R = 0.115 TYP R = 0.05 5 TYP 2.00 ±0.10 (2 SIDES) 0.70 ±0.05 1.35 ±0.10 1.35 ±0.05 3.50 ±0.05 2.10 ±0.05 0.40 ± 0.10 8 1.65 ± 0.05 1.65 ± 0.10 3.00 ±0.10 (2 SIDES) PACKAGE OUTLINE PIN 1 NOTCH R = 0.20 OR 0.25 × 45° CHAMFER PIN 1 BAR TOP MARK (SEE NOTE 6) (DCB8) DFN 0106 REV A 4 0.25 ± 0.05 0.45 BSC 1 0.23 ± 0.05 0.45 BSC 0.75 ±0.05 0.200 REF 1.35 REF 1.35 REF BOTTOM VIEW—EXPOSED PAD RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 0.00 – 0.05 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 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 3.20 – 3.45 (.126 – .136) 0.254 (.010) 8 7 6 5 3.00 ± 0.102 (.118 ± .004) (NOTE 4) 4.90 ± 0.152 (.193 ± .006) DETAIL “A” 0.52 (.0205) REF 0° – 6° TYP GAUGE PLANE 0.42 ± 0.038 (.0165 ± .0015) TYP 0.65 (.0256) BSC 1 0.53 ± 0.152 (.021 ± .006) RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 1.10 (.043) MAX 2 3 4 0.86 (.034) REF 0.18 (.007) SEATING PLANE 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 0.22 – 0.38 (.009 – .015) TYP 0.65 (.0256) BSC 0.1016 ± 0.0508 (.004 ± .002) MSOP (MS8) 0307 REV F 6930fa 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. 11 LTC6930-X.XX TYPICAL APPLICATION Dual, Matched, Digitally Programmable, Lowpass Filter, 2kHz to 256kHz VIN1 1 IN+ OUT 2 IN– V+ 3.48k 3 2k VIN2 V DIV/CLK OUT 2 IN– V+ 1μF GND RX 5 8 0 –20 VOUT2 7 5V 0.1μF 6 LTC1569-7 4 1 DIVA 5V 0.1μF 6 Amplitude Response IN+ 3 0.1μF – 1 3.48k 2k RX VOUT1 7 LTC1569-7 4 5V GND 1μF 8 GAIN (dB) 5V 2 3 V– DIV/CLK V+ V+ GND OUT DIVA GND 5 –60 –100 fOSC 7 32kHz 128kHz –80 5V 0.1μF 8 –40 fCUTOFF = 8kHz 1 10 100 FREQUENCY (kHz) 1000 6 LTC6930-8.192 DIVB 4 DIVB DIVC 5 6930 TA02 DIVC DIVC, DIVB, DIVA fCUTOFF 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 ThinSOT 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, 100μsec Startup, 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 12μA Supply Current at 100kHz, 0.65% Frequency Accuracy LTC6907 Micropower 40kHz to 4MHz ThinSOT Oscillator, Resistor Set 36μA Supply Current at 400kHz, 0.65% Frequency Accuracy LTC6908 Multiphase Oscillator with Spread Spectrum Modulation 2 Outputs Shifted by Either 180° or 90° 6930fa 12 Linear Technology Corporation LT 0708 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2008