FEATURES APPLICATIO S. LTC1799 1kHz to 33MHz Resistor Set SOT-23 Oscillator DESCRIPTIO TYPICAL APPLICATIO

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1 FEATRES One External Resistor Sets the Frequency Fast Start-p Time: <ms khz to MHz Frequency Range Low Profile (mm) ThinSOT TM Package Frequency Error.% khz to MHz (T A = C) Frequency Error % khz to MHz (T A = C to 7 C) ±ppm/ C Temperature Stability.%/V Supply Stability % ±% Duty Cycle khz to MHz % ±% Duty Cycle MHz to MHz ma Typical Supply Current Ω CMOS Output Driver Operates from a Single.7V to.v Supply APPLICATIO S Low Cost Precision Oscillator Charge Pump Driver Switching Power Supply Clock Reference Clocking Switched Capacitor Filters Fixed Crystal Oscillator Replacement Ceramic Oscillator Replacement Small Footprint Replacement for Econ Oscillators, LTC and LT are registered trademarks of Linear Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. LTC799 khz to MHz Resistor Set SOT- Oscillator DESCRIPTIO The LTC 799 is a precision oscillator that is easy to use and occupies very little PC board space. The oscillator frequency is programmed by a single external resistor (R SET ). The LTC799 has been designed for high accuracy operation (.% frequency error) without the need for external trim components. The LTC799 operates with a single.7v to.v power supply and provides a rail-to-rail, % duty cycle square wave output. The CMOS output driver ensures fast rise/fall times and rail-to-rail switching. The frequency-setting resistor can vary from k to M to select a master oscillator frequency between khz and MHz (V supply). The three-state DIV input determines whether the master clock is divided by, or before driving the output, providing three frequency ranges spanning khz to MHz (V supply). The LTC799 features a proprietary feedback loop that linearizes the relationship between R SET and frequency, eliminating the need for tables to calculate frequency. The oscillator can be easily programmed using the simple formula outlined below: f OSC = MHz N R SET, DIV Pin = V, N =, DIV Pin = Open, DIV Pin = + TYPICAL APPLICATIO k R SET M V.µF Basic Connection khz f OSC MHz LTC799 V SET DIV OPEN 799 TA NITS (%) Typical Distribution of Frequency Error, T A = C (khz f OSC MHz, = V) SOT- Actual Size FREQENCY ERROR (%) 799 TA

2 LTC799 ABSOLTE AXI RATI GS (Note ) W W W Supply Voltage ( ) to....v to 6V DIV to....v to ( +.V) SET to....v to ( +.V) Operating Temperature Range LTC799C... C to 7 C LTC799I... C to 8 C Storage Temperature Range... 6 C to C Lead Temperature (Soldering, sec)... C W PACKAGE/ORDER I FOR ATIO SET TOP VIEW S PACKAGE -LEAD PLASTIC SOT- T JMAX = C, θ JA = 6 C/W DIV ORDER PART NMBER LTC799CS LTC799IS S PART MARKING LTND LTNE Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = C. =.7V to.v, R L =k, C L = pf, unless otherwise noted. All voltages are with respect to. SYMBOL PARAMETER CONDITIONS MIN TYP MAX NITS f Frequency Accuracy = V khz f MHz ±. ±. % khz f MHz, LTC799C ± % khz f MHz, LTC799I ±. % (Notes, ) khz f khz ±. % MHz f MHz ±. % = V khz f MHz ±. ±. % khz f MHz, LTC799C ± % khz f MHz, LTC799I ±. % khz f khz ±. % MHz f MHz ±. % R SET Frequency-Setting Resistor Range f <.% = V kω = V kω f MAX Maximum Frequency f <.%, Pin = V = V MHz = V MHz f MIN Minimum Frequency f <.%, Pin = khz f/ T Freq Drift Over Temp (Note ) R SET =.6k ±. %/ C f/ V Freq Drift Over Supply (Note ) = V to V, R SET =.6k.. %/V Timing Jitter Pin =.6 % (Note ) Pin = Open. % Pin = V. % Long-Term Stability of Output Frequency ppm/ khr Duty Cycle (Note 7) Pin = or Open (DIV Either by or ) 9 % Pin = V (DIV by ), R SET = k to k % Operating Supply Range.7. V I S Power Supply Current R SET = k, Pin =, R L = = V.7. ma R SET =, Pin = V, R L = = V. ma = V ma V IH High Level DIV Input Voltage. V V IL Low Level DIV Input Voltage. V I DIV DIV Input Current (Note ) Pin = = V 8 µa Pin = V = V 8 µa

3 ELECTRICAL CHARACTERISTICS LTC799 The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at T A = C. =.7V to.v, R L =k, C L = pf, Pin = unless otherwise noted. All voltages are with respect to. SYMBOL PARAMETER CONDITIONS MIN TYP MAX NITS V OH High Level Output Voltage (Note ) = V I OH = ma.8.9 V I OH = ma..8 V = V I OH = ma.7.9 V I OH = ma..6 V V OL Low Level Output Voltage (Note ) = V I OL = ma.. V I OL = ma.. V = V I OL = ma.. V I OL = ma..7 V t r Rise Time = V Pin = or Floating, R L = ns (Note 6) Pin = V, R L = 7 ns = V Pin = or Floating, R L = 9 ns Pin = V, R L = ns t f Fall Time = V Pin = or Floating, R L = ns (Note 6) Pin = V, R L = 6 ns Note : Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note : Frequencies near khz and MHz may be generated using two different values of R SET (see the Table in the Applications Information section). For these frequencies, the error is specified under the following assumption: < R SET k. The frequency accuracy for f OSC = MHz is guaranteed by design and test correlation. Note : Frequency accuracy is defined as the deviation from the f OSC equation. = V Pin = or Floating, R L = 9 ns Pin = V, R L = ns Note : 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 % tested. Note : To conform with the Logic IC Standard convention, current out of a pin is arbitrarily given as a negative value. Note 6: Output rise and fall times are measured between the % and 9% power supply levels. These specifications are based on characterization. Note 7: Guaranteed by V test.

4 LTC799 TYPICAL PERFOR A CE CHARACTERISTICS W VARIATION (%) Frequency Variation vs R SET T A = C GARANTEED LIMITS APPLY OVER k TO k RANGE TYPICAL HIGH TYPICAL LOW VARIATION (%) Frequency Variation Over Temperature R SET =.6k OR OR TYPICAL HIGH TYPICAL LOW R SET (kω) 799 G. 6 8 TEMPERATRE ( C) 799 G JITTER (%) Peak-to-Peak Jitter vs Frequency k k M M M PT FREQENCY, f (Hz) 799 G SPPLY CRRENT (ma) Supply Current vs Output Frequency T A = C C L = pf R L = M (V) (V) (V) (V) (V) (V) k k M M M PT FREQENCY, f (Hz) 799 G Output Resistance vs Supply Voltage T A = C LTC799 Output Operating at MHz, V S = V = V, R SET = k, C L = pf LTC799 Output Operating at MHz, V S = V = V, R SET =, C L = pf PT RESISTANCE (Ω) 8 6 PT SORCING CRRENT PT SINKING CRRENT V/DIV.ns/DIV 799 G6 V/DIV ns/div 799 G SPPLY VOLTAGE (V) 799 G

5 LTC799 PI F CTIO S (Pin ): Voltage Supply (.7V.V). This supply must be kept free from noise and ripple. It should be bypassed directly to a ground plane with a.µf capacitor. (Pin ): Ground. Should be tied to a ground plane for best performance. SET (Pin ): Frequency-Setting Resistor Input. The value of the resistor connected between this pin and determines the oscillator frequency. The voltage on this pin is held by the LTC799 to approximately.v below the voltage. For best performance, use a precision metal film resistor with a value between and k and limit the capacitance on this pin to less than pf. DIV (Pin ): Divider-Setting Input. This three-state input selects among three divider settings, determining the value of N in the frequency equation. Pin should be tied to for the setting, the highest frequency range. Floating Pin divides the master oscillator by. Pin should be tied to for the setting, the lowest frequency range. To detect a floating DIV pin, the LTC799 attempts to pull the pin toward midsupply. This is realized with two internal current sources, one tied to and Pin and the other one tied to ground and Pin. Therefore, driving the DIV pin high requires sourcing approximately µa. Likewise, driving DIV low requires sinking µa. When Pin is floated, preferably it should be bypassed by a nf capacitor to ground or it should be surrounded by a ground shield to prevent excessive coupling from other PCB traces. (Pin ): Oscillator Output. This pin can drive kω and/or pf loads. Larger loads may cause inaccuracies due to supply bounce at high frequencies. Transients will not cause latchup if the current into/out of the pin is limited to ma. BLOCK DIAGRA W R SET I RES SET + V BIAS + GAIN = V RES =.V ±% ( V SET ) MASTER OSCILLATOR I RES ƒ MO = MHz kω ( V SET ) PROGRAMMABLE DIVIDER (, OR ) DIVIDER SELECT µa I RES THREE-STATE INPT DETECT DIV µa 799 BD

6 LTC799 THEORY OF OPERATIO As shown in the Block Diagram, the LTC799 s master oscillator is controlled by the ratio of the voltage between the and SET pins and the current entering the SET pin (I RES ). The voltage on the SET pin is forced to approximately.v below by the PMOS transistor and its gate bias voltage. This voltage is accurate to ±7% at a particular input current and supply voltage (see Figure ). The effective input resistance is approximately k. A resistor R SET, connected between the and SET pins, locks together the voltage ( V SET ) and current, I RES, variation. This provides the LTC799 s high precision. The master oscillation frequency reduces to: Ω ƒ MO = MHz R SET The LTC799 is optimized for use with resistors between and k, corresponding to master oscillator frequencies between.mhz and MHz. Accurate frequencies up to MHz (R SET = k) are attainable if the supply voltage is greater than V. To extend the output frequency range, the master oscillator signal may be divided by, or before driving (Pin ). The divide-by value is determined by the state of the DIV input (Pin ). Tie DIV to or drive it below.v to select. This is the highest frequency range, with the master output frequency passed directly to. The DIV pin may be floated or driven to midsupply to select, the intermediate frequency range. The lowest frequency range,, is selected by tying DIV to or driving it to within.v of. Figure shows the relationship between R SET, divider setting and output frequency, including the overlapping frequency ranges near khz and MHz. The CMOS output driver has an on resistance that is typically less than Ω. In the (high frequency) mode, the rise and fall times are typically 7ns with a V supply and ns with a V supply. These times maintain a clean square wave at MHz (MHz at V supply). In the and modes, where the output frequency is much lower, slew rate control circuitry in the output driver increases the rise/fall times to typically ns for a V supply and 9ns for a V supply. The reduced slew rate lowers EMI (electromagnetic interference) and supply bounce.. T A = C. V RES = V SET... = V = V RSET (kω) MOST ACCRATE OPERATION.9.8 I RES (µa) 799 F k k M M M DESIRED PT FREQENCY (Hz) 799 F Figure. V SET Variation with I RES Figure. R SET vs Desired Output Frequency 6

7 LTC799 APPLICATIO S I FOR ATIO W SELECTING THE DIVIDER SETTING AND RESISTOR The LTC799 s master oscillator has a frequency range spanning.mhz to MHz. However, accuracy may suffer if the master oscillator is operated at greater than MHz with a supply voltage lower than V. A programmable divider extends the frequency range to greater than three decades. Table describes the recommended frequencies for each divider setting. Note that the ranges overlap; at some frequencies there are two divider/resistor combinations that result in the desired frequency. In general, any given oscillator frequency (f OSC ) should be obtained using the lowest master oscillator frequency. Lower master oscillator frequencies use less power and are more accurate. For instance, f OSC = khz can be obtained by either R SET =, N =, master oscillator = MHz or R SET = k, N =, master oscillator = MHz. The R SET = k is preferred for lower power and better accuracy. Table. Frequency Range vs Divider Setting DIVIDER SETTING FREQENCY RANGE DIV (Pin ) = >khz * DIV (Pin ) = Floating khz to MHz DIV (Pin ) = < khz * At master oscillator frequencies greater than MHz (R SET < Ω), the LTC799 may suffer reduced accuracy with a supply voltage less than V. After choosing the proper divider setting, determine the correct frequency-setting resistor. Because of the linear correspondence between oscillation period and resistance, a simple equation relates resistance with frequency. MHz RSET =, N = N fosc (R SETMIN = k (V Supply), k (V Supply), R SETMAX = M) Any resistor, R SET, tolerance adds to the inaccuracy of the oscillator, f OSC. ALTERNATIVE METHODS OF SETTING THE PT FREQENCY OF THE LTC799 The oscillator may be programmed by any method that sources a current into the SET pin (Pin ). The circuit in Figure sets the oscillator frequency using a programmable current source and in the expression for f OSC, the resistor R SET is replaced by the ratio of.v/i CONTROL. As already explained in the Theory of Operation, the voltage difference between and SET is approximately.v, therefore, the Figure circuit is less accurate than if a resistor controls the oscillator frequency. Figure shows the LTC799 configured as a VCO. A voltage source is connected in series with an external resistor. The output frequency, f OSC, will vary with V CONTROL, that is the voltage source connected between and the SET pin. Again, this circuit decouples the relationship between the input current and the voltage between and SET; the frequency accuracy will be degraded. The oscillator frequency, however, will monotonically increase with decreasing V CONTROL. I CONTROL µa TO µa V CONTROL V TO.V +.µf Figure. Current Controlled Oscillator.µF R SET LTC799 SET DIV 799 F LTC799 SET DIV 799 F khz TO MHz (APPROXIMATE, SEE TEXT) N = ƒ MHz OSC Ω I N.V CONTROL I CONTROL EXPRESSED IN (A) N = ƒ MHz OSC V CONTROL N.V R SET ( ) Figure. Voltage Controlled Oscillator 7

8 LTC799 APPLICATIO S I FOR ATIO POWER SPPLY REJECTION Low Frequency Supply Rejection (Voltage Coefficient) Figure shows the output frequency sensitivity to power supply voltage at several different temperatures. The LTC799 has a conservative guaranteed voltage coefficient of.%/v but, as Figure shows, the typical supply sensitivity is lower. FREQENCY DEVIATION (%)..... W R SET =.6k PIN = FLOATING ( ) C C.... SPPLY VOLTAGE (V) 8 C F START-P TIME The start-up time and settling time to within % of the final value can be estimated by t START R SET (.8µs/kΩ) + µs. Note the start-up time depends on R SET and it is independent from the setting of the divider pin. For instance with R SET = k, the LTC799 will settle with % of its khz final value (N = ) in approximately 6µs. Figure 6 shows start-up times for various R SET resistors. Figure 7 shows an application where a second set resistor R SET is connected in parallel with set resistor R SET via switch S. When switch S is open, the output frequency of the LTC799 depends on the value of the resistor R SET. When switch S is closed, the output frequency of the LTC799 depends on the value of the parallel combination of R SET and R SET. The start-up time and settling time of the LTC799 with switch S open (or closed) is described by t START shown above. Once the LTC799 starts and settles, and switch S closes (or opens), the LTC799 will settle to its new output frequency within approximately µs. Figure. Supply Sensitivity High Frequency Power Supply Rejection The accuracy of the LTC799 may be affected when its power supply generates significant noise with frequency contents in the vicinity of the programmed value of f OSC. If a switching power supply is used to power up the LTC799, and if the ripple of the power supply is more than a few tens of millivolts, make sure the switching frequency and its harmonics are not related to the output frequency of the LTC799. Otherwise, the oscillator may show an additional.% to.% of frequency error. If the LTC799 is powered by a switching regulator and the switching frequency or its harmonics coincide with the output frequency of the LTC799, the jitter of the oscillator output may be affected. This phenomenon will become noticeable if the switching regulator exhibits ripples beyond mv. FREQENCY ERROR (%) 6 V OR V S R SET R SET.6k k T A = C = V 6 TIME AFTER POWER APPLIED (µs) Figure 6. Start-p Time LTC799 SET DIV 799 F7 799 F6 ( N R SET ) ( ) f OSC = MHz N R SET //R SET f OSC = MHz OR 8 Figure 7

9 LTC799 APPLICATIO S I FOR ATIO Jitter W The typical jitter is listed in the Electrical Characteristics and shown in the Typical Performance Characteristics. These specifications assume that the capacitance on SET (Pin ) is limited to less than pf, as suggested in the Pin Functions description. If this requirement is not met, the jitter will increase. For more information, contact Linear Technology Applications group. TYPICAL APPLICATIO S Low Power 8Hz to 8kHz Sine Wave Generator (I Q < ma) C.µF V f OSC LTC799 V R SET V, N = SW OPEN, N = SET DIV C.µF V 8Hz f SINE 8kHz, N = 8Hz f SINE 8Hz, N = HC CLOCK A ENABLE A V DD ENABLE B RESET A V SS CLOCK B RESET B QA QA QA QA QB QB QB QB C µf R k f OSC 6 V C.µF R6 R.k R.k R k NC SA LPA BPA HPA/NA INV A LTC67- CLK A V SB LPB BPB HPB/NB INV B R H 9k R L.k 6 9 R.k R k R6 k R.k SINEWAVE f SINE = MHz N 6R SET 799 TA CLOCK-TNABLE LOWPASS FILTER WITH A STOPBAND NOTCH AT THE rd HARMONIC f OSC 6 ( ) 9

10 LTC799 TYPICAL APPLICATIO S V Digitally Controlled Oscillator with khz to 8kHz Range (N =, Pin = ) V CLK D IN CS/LD CLK D IN CS/LD D V R R LTC69 9 R + 8 V CC 7 V 6 REF / LT9 R 8 C.µF R R6 R8 R7 7 + / LT9 V / LT9 + C.µF 6 R S I = V ( V SET ) C.µF C 96 LTC799 SET DIV khz TO 8kHz V 799 TA6 C: DAC CODE C 8 C f OSC = khz 96 NOTES:. FOR N = (PIN OPEN) THE RANGE IS khz TO 8kHz. FOR N = (PIN = ) THE RANGE IS khz TO 8.MHz. DRIVING PIN OF THE LTC799 WITH A -STATE LOGIC DEVICE GIVES A RANGE OF khz TO 8.MHz Input Code vs Output Frequency (N =, Pin = ) 7 f (khz) DAC CODE 799 TA7

11 LTC799 PACKAGE DESCRIPTIO S Package -Lead Plastic SOT- (Reference LTC DWG # -8-6) (Reference LTC DWG # -8-6).8. (..8) (NOTE ) A A A L SOT- (Original).9. (..7).. (..6).9. (..).. (..) SOT- (ThinSOT). MAX (.9 MAX).. (..).8.9 (..).. REF (..9 REF).6. (..8)..7 (.9.69) (NOTE ) PIN ONE.9 (.7) REF.. (..) (PLCS, NOTE ). (.8) DATM A A A L NOTE:. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS. DIMENSIONS ARE IN (INCHES).9. (..8) (NOTE ). DRAWING NOT TO SCALE. DIMENSIONS ARE INCLSIVE OF PLATING. DIMENSIONS ARE EXCLSIVE OF MOLD FLASH AND METAL BRR 6. MOLD FLASH SHALL NOT EXCEED.mm 7. PACKAGE EIAJ REFERENCE IS: SC-7A (EIAJ) FOR ORIGINAL JEDEL MO-9 FOR THIN.9 (.7) REF A S SOT- 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.

12 LTC799 TYPICAL APPLICATIO S Shutting Down the LTC799 V ON/SHDN 7AC R C.µF LTC799 SET DIV 799 TA8 Temperature-to-Frequency Converter Output Frequency vs Temperature R T k THERMISTOR V C.µF LTC799 SET DIV R T : YSI TA f OSC = MHz R T FREQENCY (khz) 8 6 MAX TYP MIN TEMPERATRE ( C) 799 TA 799f LT/TP 8 K PRINTED IN SA Linear Technology Corporation 6 McCarthy Blvd., Milpitas, CA 9-77 (8) -9 FAX: (8) -7 LINEAR TECHNOLOGY CORPORATION

13 This datasheet has been download from: Datasheets for electronics components.

FEATURES TYPICAL APPLICATIO LTC MHz to 3GHz RF Power Detector. in SC70 Package DESCRIPTIO APPLICATIO S

FEATURES TYPICAL APPLICATIO LTC MHz to 3GHz RF Power Detector. in SC70 Package DESCRIPTIO APPLICATIO S 300MHz to 3GHz RF Power Detector in SC70 Package FEATRES Temperature Compensated Internal Schottky Diode RF Detector Wide Input Frequency Range: 300MHz to 3GHz Wide Input Power Range: 30dBm to 6dBm Buffered