LTC6905-XXX Series Fixed Frequency SOT-23 Oscillator U FEATURES DESCRIPTIO ■ The LTC®6905-XXX series of parts are precision, fixed frequency, silicon oscillators designed to minimize board space while maximizing accuracy and ease of use. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ No External Components to Set Frequency Frequency Error ±0.5% Typical Fast Start-Up Time: 100µs Typical ±20ppm/°C Temperature Stability Output Enable Provided Includes Divide by 1, 2 or 4 Rise Time: 0.5ns, CL = 5pF Timing Jitter: <0.8% Typical 50% ±2.5% Duty Cycle IS = 8mA Typical (fOSC = 100MHz, CL = 5pF) CMOS Output Drives 600Ω Load Single Supply 2.7V to 5.5V Low Profile (1mm) ThinSOTTM Package U APPLICATIO S ■ ■ ■ Programmed at the factory to a fixed frequency, the LTC6905-XXX series of parts need no external trim components. An internal three-state divider allows for division of the master clock by 1, 2 or 4, providing 3 frequencies (for each device). The LTC6905-XXX series operate with a single 2.7V to 5.5V power supply and provide a rail-to-rail, 50% duty cycle, square wave output. The OE pin will disable the output when brought low and synchronously enable the output when brought high, avoiding pulse slivers. The four products of the LTC6905-XXX family are: Data Clocks for High Reliability Applications High Vibration, High Acceleration Environments Replacement for Fixed Crystal and Ceramic Oscillators , LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 6614313, 6342817. LTC6905-133: fOSC = 133MHz, 66.7MHz, 33.3MHz LTC6905-100: fOSC = 100MHz, 50MHz, 25MHz LTC6905-96: fOSC = 96MHz, 48MHz, 24MHz LTC6905-80: fOSC = 80MHz, 40MHz, 20MHz The LTC6905-XXX series of parts are designed with a factory trim option to modify the divider ratios from 1, 2, 4 to 8, 16, 32. A second trim option allows for additional master clock frequencies. For the alternate divider ratios and unlisted frequencies, contact LTC marketing. U TYPICAL APPLICATIO Typical Distribution of Frequency Error, TA = 25°C 40 VS = 3V Basic Connection 30 fOSC = 133MHz 1 2 3 OUT V+ LTC6905-133 5 3V GND OE UNITS 3V 0.1µF 20 ÷1 DIV 6905x TA01 4 ÷2 OPEN 10 ÷4 0 –1 –0.5 0.0 0.5 % FREQUENCY ERROR 1 6905x TA02 6905xf 1 LTC6905-XXX Series W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) Supply Voltage (V +) to GND ........................– 0.3V to 6V DIV to GND .................................... – 0.3V to (V + + 0.3V) OE to GND ..................................... – 0.3V to (V + + 0.3V) Output Short-Circuit Duration (Note 6) ........... Indefinite Operating Temperature Range (Note 8) LTC6905C .......................................... – 40°C to 85°C LTC6905I ............................................ – 40°C to 85°C LTC6905H ........................................ – 40°C to 125°C Specified Temperature Range (Note 8) LTC6905C ............................................... 0°C to 70°C LTC6905I ............................................ – 40°C to 85°C LTC6905H ........................................ – 40°C to 125°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C TOP VIEW V+ 5 OUT 1 GND 2 OE 3 4 DIV S5 PACKAGE 5-LEAD PLASTIC SOT-23 TJMAX = 125°C, θJA = 150°C/W ORDER PART NUMBER S5 PART MARKING* LTC6905CS5-133 LTC6905IS5-133 LTC6905HS5-133 LTC6905CS5-100 LTC6905IS5-100 LTC6905HS5-100 LTC6905CS5-96 LTC6905IS5-96 LTC6905HS5-96 LTC6905CS5-80 LTC6905IS5-80 LTC6905HS5-80 LTBPM LTBPK LTBPJ LTBPH *The temperature grade is identified by a label on the shipping container. ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C or as noted. OE = DIV = V+, V+ = 2.7V to 3.6V, RL = 15k, CL = 5pF, unless otherwise noted. All voltages are with respect to GND. SYMBOL PARAMETER CONDITIONS ∆f Frequency Accuracy (Notes 2, 7) LTC6905C-XXX TA = 25°C, V+ = 3V 0°C < TA < 70°C MIN TYP MAX UNITS ±0.5 ● ±1.0 ±1.5 % % LTC6905I-XXX 25°C < TA < 85°C – 40°C < TA < 85°C ● ±1.8 ±2.9 % % LTC6905H-XXX 25°C < TA < 125°C – 40°C < TA < 125°C ● ±2.3 ±2.9 % % V+ = 5V ∆f/∆T Freq Drift Over Temp (Note 2) ∆f/∆V Freq Drift Over Supply (Notes 2, 7) ● V+ = 2.7V to 3.6V Timing Jitter (Note 3) Long-Term Stability of Output Frequency V+ ±1.5 % ±20 ppm/°C 0.5 %/V 0.8 % 300 Duty Cycle ● 47.5 Operating Supply Range ● 2.7 50 ppm/√kHr 52.5 % 5.5 V 6905xf 2 LTC6905-XXX Series ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full specified temperature range, otherwise specifications are at TA = 25°C or as noted. OE = DIV = V+, V+ = 2.7V to 3.6V, RL = 15k, CL = 5pF, unless otherwise noted. All voltages are with respect to GND. SYMBOL IS PARAMETER CONDITIONS Power Supply Current DIV = V+ (÷ 1), V+ = 3.6V MIN LTC6905-133 LTC6905-100 LTC6905-96 LTC6905-80 DIV = 0 (÷ 4), V+ = 3.6V LTC6905-133 LTC6905-100 LTC6905-96 LTC6905-80 TYP MAX ● ● ● ● 10 8 8 7 15 12 12 11 mA mA mA mA ● ● ● ● 5 4 4 3.5 8 7 7 6 mA mA mA mA VIH High Level DIV or OE Pins Input Voltage ● V+ – 0.15 VIL Low Level DIV or OE Pins Input Voltage ● IDIV DIV Input Current (Note 4) DIV = V + DIV = 0V V + = 5.5V V + = 5.5V ● ● – 40 UNITS V 15 – 11 0.2 V 40 µA µA IOE OE Input Current (Note 4) OE = V+ OE = 0V V + = 5.5V V + = 5.5V VOH High Level Output Voltage (Note 4) V + = 5.5V IOH = – 1mA IOH = – 4mA ● ● V + = 2.7V IOH = – 1mA IOH = – 4mA ● ● V + = 5.5V IOL = 1mA IOL = 4mA ● ● 0.05 0.2 0.25 0.3 V V V + = 2.7V IOL = 1mA IOL = 4mA ● ● 0.1 0.4 0.3 0.5 V V VOL tr, tf Low Level Output Voltage (Note 4) OUT Rise/Fall Time (Note 5) Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Frequency accuracy is tested with DIV = V+ (÷1). Other divide ratios are guaranteed by design. Note 3: Jitter is the ratio of the peak-to-peak distribution of the period to the mean of the period. This specification is based on characterization and is not 100% tested. Note 4: To conform with the Logic IC Standard convention, current out of a pin is arbitrarily given as a negative value. Note 5: Output rise and fall times are measured between the 10% and 90% power supply levels. 15 –11 µA µA 5.25 5.20 5.45 5.30 V V 2.5 2.3 2.6 2.5 V V 0.5 ns Note 6: A heat sink may be required to keep the junction temperature below the absolute maximum when the output is shorted indefinitely. Note 7: The LTC6905 is optimized for the performance with a 3V power supply voltage. Refer to Typical Performance Characteristics curves in this data sheet for additional information regarding the LTC6905 voltage coefficient, especially between 4.5V and 5.5V. Please consult LTC Marketing for parts optimized for 5V operation. Note 8: The LTC6905C-XXX is guaranteed functional over the operating temperature range and is guaranteed to meet specified performance from 0°C to 70°C. The LTC6905C-XXX 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 LTC6905I-XXX is guaranteed to meet specified performance from –40°C to 85°C. 6905xf 3 LTC6905-XXX Series U W TYPICAL PERFOR A CE CHARACTERISTICS Supply Current vs Frequency 18 5.5V 2.7V 16 2.00 14 FREQUENCY ERROR (%) SUPPLY CURRENT (mA) Frequency Error vs Supply Voltage 2.50 ÷1 12 10 ÷2 8 ÷1 ÷4 6 ÷2 4 ÷4 LTC6905-133 1.50 1.00 0.50 LTC6905-100 LTC6905-96 LTC6905-80 O 2 0 –0.50 0 100 50 200 150 2.5 3 FREQUENCY (MHz) 3.5 4 4.5 SUPPLY VOLTAGE (V) Jitter vs Frequency 45 Frequency vs Temperature 1.0 1.20 0.8 40 ÷4 35 30 ÷2 PERCENTAGE ERROR (%) 1.00 ÷1 0.80 JITTER (%) OUTPUT RESISTANCE (Ω) 5.5 6905x G09 6905x G01 ROUT vs V+ 5 25 20 0.60 0.40 15 10 0.6 0.4 0.2 0 –0.2 –0.4 –0.6 0.20 5 –0.8 0 2.5 3 3.5 4 4.5 SUPPLY VOLTAGE (V) 5 5.5 0 0 20 6905x G04 40 60 80 100 120 140 160 180 FREQUENCY (MHz) –1.0 –40 –20 0 20 40 60 80 100 120 TEMPERATURE (°C) 6905x G08 6905x G05 LTC6905-80 Output Operating at 20MHz, VS = 3V 0.75V/DIV LTC6905-133 Output Operating at 133MHz, VS = 3V 0.75V/DIV 10ns/DIV 6905x G06 2.5ns/DIV 6905x G07 6905xf 4 LTC6905-XXX Series U U U PI FU CTIO S V+ (Pin 1): Voltage Supply (2.7V ≤ V+ ≤ 5.5V). This supply must be kept free from noise and ripple. It should be bypassed directly to the GND (Pin 2) with a 0.1µF capacitor or higher. to V+ for the ÷1 setting, the highest frequency range. Floating Pin 4 divides the master oscillator by 2. Pin 4 should be tied to GND for the ÷4 setting, the lowest frequency range. To detect a floating DIV pin, the LTC6905 attempts to pull the pin toward midsupply. This is realized with two internal current sources, one tied to V + and Pin 4 and the other one tied to ground and Pin 4. Therefore, driving the DIV pin high requires sourcing approximately 15µA. Likewise, driving DIV low requires sinking 15µA. When Pin 4 is floated, it should be bypassed by a 1nF capacitor to ground or it should be surrounded by a ground shield to prevent excessive coupling from other PCB traces. GND (Pin 2): Ground. Should be tied to a ground plane for best performance. OE (Pin 3): Output Enable. Pull to V+ or leave floating to enable the output driver (Pin 5). Pull low to disable the output. The output is disabled asynchronously. Pulling OE pin low will immediately disable the output. Pulling the OE pin high will bring the output high on the next low to high transition of the clock. This eliminates pulse slivers. OUT (Pin 5): Oscillator Output. This pin can drive 5kΩ and/or 5pF loads. For heavier loads, refer to the Applications Information section. DIV (Pin 4): Divider-Setting Input. This three-state input selects among three divider settings. Pin 4 should be tied W BLOCK DIAGRA 3 1 OE VRES = 1V ±5% (V+ – VSET) V+ PROGRAMMABLE DIVIDER (N = 1, 2 OR 4) + RSET IRES GAIN = 1 fOSC = fMO N DIVIDER SELECT V+ fMO 2 GND – VBIAS 5 MASTER OSCILLATOR – + – OUT 15µA DIV THREE-STATE INPUT DETECT IRES + 4 15µA GND 6905x BD Table 1. LTC6905-XXX Frequency Settings DIV SETTING LTC6905-133 LTC6905-100 LTC6905-96 LTC6905-80 V+ 133.33MHz 100MHz 96MHz 80MHz OPEN 66.66MHz 50MHz 48MHz 40MHz GND 33.33MHz 25MHz 24MHz 20MHz 6905xf 5 LTC6905-XXX Series U W U U APPLICATIO S I FOR ATIO START-UP TIME The start-up and settling time to within 1% of the final frequency is typically 100µs. MAXIMUM OUTPUT LOAD The LTC6905 output (Pin 5) can drive a capacitive load (CLOAD) of 5pF or more. Performance driving a CLOAD greater than 5pF depends on the oscillator’s frequency (fOSC) and output resistance (ROUT). The output rise time or fall time due to ROUT and CLOAD is equal to 2.2 • ROUT • CLOAD (from 10% to 90% of the rise or fall transition). If the total output rise time plus fall time is arbitrarily specified to be equal to or less than 20% of the oscillator’s period (1/ fOSC), then the maximum output CLOAD in picofarads (pF) should be equal to or less than [45454/(ROUT • fOSC)] (ROUT in ohms and fOSC in MHz). then the oscillator frequency may show an additional error if the switching frequency is 1.4MHz (80MHz/64). The magnitude of this effect is heavily dependent on supply bypass and routing. JITTER AND POWER SUPPLY NOISE If the LTC6905 is powered by a supply that has frequency content equal to the output frequency then the output jitter may increase. In addition, power supply ripple in excess of 20mV at any frequency may increase jitter. Higher divide ratios will result in lower percentage jitter. For example, jitter percentage of the LTC6905-80 operating at 20MHz is lower than for the same part operating at 80MHz. Please consult the Jitter vs Frequency graph showing jitter at various divider ratios. Example: An LTC6905-100 is operating with a 3V power supply and is set for a fOSC = 50MHz. LTC6905 SUGGESTED CRITICAL COMPONENT LAYOUT ROUT with V+ = 3V is 27Ω (using the ROUT vs V+ graph in the Typical Performance Characteristics). In order to provide the specified performance, it is required that the supply bypass capacitor be placed as close as possible to the LTC6905. The following additional rules should be followed for best performance: The maximum output CLOAD should be equal to or less than [45454/(27 • 50)] = 33.6pF. The lowest resistive load Pin 5 can drive can be calculated using the minimum high level output voltage in the Electrical Characteristics. With a V+ equal to 5.5V and 4mA output current, the minimum high level output voltage is 5.2V and the lowest resistive load Pin 5 can drive is 1.30k (5.2V/4mA). With a V+ equal to 2.7V and 4mA output current, the minimum high level output voltage is 2.4V and the lowest resistive load Pin 5 can drive is 600Ω (2.4V/4mA). 1) The bypass capacitor must be placed as close as possible to the LTC6905, and no vias should be placed between the capacitor and the LTC6905. The bypass capacitor must be on the same side of the circuit board as the LTC6905. 2) If a ground plane is used, the connection of the LTC6905 to the ground plane should be as close as possible to the LTC6905 GND pin and should be composed of multiple, high current capacity vias. FREQUENCY ACCURACY AND POWER SUPPLY NOISE The frequency accuracy of the LTC6905 may be affected when its power supply generates noise with frequency contents equal to fMO/64 or its multiples. fMO is the highest frequency for an LTC6905-XXX which is with DIV = V+ (÷1). This is also the frequency indicated in the part number (i.e., LTC6905-100, fMO = 100MHz). fMO/64 is the master oscillator control loop frequency. For example, if the LTC6905-80 with a master oscillator frequency of 80MHz is powered by a switching regulator, C LTC6905 6905x F02 Figure 2. LTC6905 Suggested Critical Component Layout 6905xf 6 LTC6905-XXX Series U PACKAGE DESCRIPTIO S5 Package 5-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1635) 0.62 MAX 0.95 REF 2.90 BSC (NOTE 4) 1.22 REF 3.85 MAX 2.62 REF 1.4 MIN 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6. JEDEC PACKAGE REFERENCE IS MO-193 1.90 BSC S5 TSOT-23 0302 6905xf 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. 7 LTC6905-XXX Series U TYPICAL APPLICATIO S Driving a 50Ω Cable with the LTC6905 1 3V 0.1µF 2 3 3V 5 V+ OUT LTC6905-XXX 50Ω CABLE 950Ω VOUT 20 50Ω GND OE 6905x TA02 4 DIV Driving the DIV Pin Without Three-State Buffers A 0 0 1 1 B 0 1 0 1 DIV ÷1 ÷2 ÷2 ÷4 3V 0.1µF 3V A 3V 1 2 3 V+ OUT LTC6905-XXX 5 GND OE DIV 4 10k 6905x TA04 10k B RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1799 1kHz to 33MHz ThinSOT Oscillator Single Output, High Frequency Operation LTC6900 1kHz to 20MHz ThinSOT Oscillator Single Output Lower Power LTC6902 Multiphase Oscillator with Spread Spectrum Modulation 2-, 3- or 4-Phase Outputs LTC6903/LTC6904 1kHz to 68MHz Serial Port Programmable Oscillator 3-Wire or I2CTM Programmable LTC6905 17MHz to 170MHz Resistor Set ThinSOT Oscillator Single Resistor Sets Frequency LTC6906 Micropower, 10kHz to 1MHz Resistor Set ThinSOT Oscillator Ultralow Power, Resistor Sets Frequency 6905xf 8 Linear Technology Corporation LT/TP 0205 1K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2005