查询LTC1799供应商 LTC1799 1kHz to 33MHz Resistor Set SOT-23 Oscillator U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO The LTC®1799 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 (RSET). The LTC1799 has been designed for high accuracy operation (≤1.5% frequency error) without the need for external trim components. One External Resistor Sets the Frequency Fast Start-Up Time: < 1ms 1kHz to 33MHz Frequency Range Low Profile (1mm) ThinSOTTM Package Frequency Error ≤1.5% 5kHz to 20MHz (TA = 25°C) Frequency Error ≤ 2% 5kHz to 20MHz (TA = 0°C to 70°C) ±40ppm/°C Temperature Stability 0.05%/V Supply Stability 50% ±1% Duty Cycle 1kHz to 2MHz 50% ±5% Duty Cycle 2MHz to 20MHz 1mA Typical Supply Current 100Ω CMOS Output Driver Operates from a Single 2.7V to 5.5V Supply U 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. The LTC1799 operates with a single 2.7V to 5.5V power supply and provides a rail-to-rail, 50% 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 3k to 1M to select a master oscillator frequency between 100kHz and 33MHz (5V supply). The three-state DIV input determines whether the master clock is divided by 1, 10 or 100 before driving the output, providing three frequency ranges spanning 1kHz to 33MHz (5V supply). The LTC1799 features a proprietary feedback loop that linearizes the relationship between RSET and frequency, eliminating the need for tables to calculate frequency. The oscillator can be easily programmed using the simple formula outlined below: 100, DIV Pin = V + 10k fOSC = 10MHz • , N = 10, DIV Pin = Open N • RSET 1, DIV Pin = GND U Typical Distribution of Frequency Error, TA = 25°C (5kHz ≤ fOSC ≤ 20MHz, V + = 5V) TYPICAL APPLICATIO 25 Basic Connection 1 0.1µF 3k ≤ RSET ≤ 1M 2 3 V+ OUT LTC1799 5V GND SET DIV 1799 TA01 SOT-23 Actual Size 20 1kHz ≤ fOSC ≤ 33MHz 5 UNITS (%) 5V 4 ÷100 ÷1 ÷10 15 10 OPEN 5 0 –1.25 –0.75 –0.25 0 0.25 0.75 FREQUENCY ERROR (%) 1.25 1799 TA02 1 LTC1799 W W W AXI U U ABSOLUTE RATI GS U U W PACKAGE/ORDER I FOR ATIO (Note 1) ORDER PART NUMBER Supply Voltage (V +) to GND ........................– 0.3V to 6V DIV to GND .................................... – 0.3V to (V + + 0.3V) SET to GND ................................... – 0.3V to (V + + 0.3V) Operating Temperature Range LTC1799C ............................................... 0°C to 70°C LTC1799I ............................................ – 40°C to 85°C Storage Temperature Range ................. – 65°C to 150°C Lead Temperature (Soldering, 10 sec).................. 300°C TOP VIEW V+ 1 LTC1799CS5 LTC1799IS5 5 OUT GND 2 SET 3 4 DIV S5 PART MARKING S5 PACKAGE 5-LEAD PLASTIC SOT-23 LTND LTNE TJMAX = 125°C, θJA = 256°C/W 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 TA = 25°C. V+ = 2.7V to 5.5V, RL=5k, CL = 5pF, unless otherwise noted. All voltages are with respect to GND. SYMBOL PARAMETER CONDITIONS ∆f Frequency Accuracy V+ = 5V (Notes 2, 3) V+ = 3V MIN 5kHz ≤ f ≤ 20MHz 5kHz ≤ f ≤ 20MHz, LTC1799C 5kHz ≤ f ≤ 20MHz, LTC1799I 1kHz ≤ f ≤ 5kHz 20MHz ≤ f ≤ 33MHz 5kHz ≤ f ≤ 10MHz 5kHz ≤ f ≤ 10MHz, LTC1799C 5kHz ≤ f ≤ 10MHz, LTC1799I 1kHz ≤ f ≤ 5kHz 10MHz ≤ f ≤ 20MHz TYP MAX UNITS ±0.5 ±1.5 ±2 ±2.5 % % % % % ±1.5 ±2 ±2.5 % % % % % 200 200 kΩ kΩ ● ● ±2.5 ±2.5 ±0.5 ● ● ±2.5 ±2.5 RSET Frequency-Setting Resistor Range ∆f < 1.5% V + = 5V V + = 3V fMAX Maximum Frequency ∆f < 2.5%, Pin 4= 0V V + = 5V V + = 3V fMIN Minimum Frequency ∆f < 2.5%, Pin 4= V + 1 kHz ∆f/∆T Freq Drift Over Temp (Note 3) RSET = 31.6k ● ±0.004 %/°C ∆f/∆V Freq Drift Over Supply (Note 3) V+ = 3V to 5V, RSET = 31.6k ● 0.05 Timing Jitter (Note 4) Pin 4 = V + 5 10 33 20 V+ Operating Supply Range IS Power Supply Current ● ● 49 45 ● 2.7 RSET = 200k, Pin 4 = V +, RL = ∞ V + = 5V ● RSET = 10k, Pin 4 = 0V, RL = ∞ V + = 5V V + = 3V ● ● High Level DIV Input Voltage ● V+ – 0.4 VIL Low Level DIV Input Voltage ● 2 DIV Input Current (Note 5) Pin 4 = V + V + = 5V Pin 4 = 0V V + = 5V ● ● –8 %/V % % % 300 Pin 4 = V + or Open (DIV Either by 100 or 10) Pin 4 = 0V (DIV by 1), RSET = 5k to 200k VIH IDIV 0.1 0.06 0.13 0.4 Pin 4 = Open Pin 4 = 0V Long-Term Stability of Output Frequency Duty Cycle (Note 7) MHz MHz ppm/√kHr 50 50 51 55 % % 5.5 V 0.7 1.1 mA 2.4 2 mA mA V 5 –5 0.5 V 8 µA µA LTC1799 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. V+ = 2.7V to 5.5V, RL=5k, CL = 5pF, Pin 4 = V+ unless otherwise noted. All voltages are with respect to GND. SYMBOL PARAMETER CONDITIONS VOH High Level Output Voltage (Note 5) V + = 5V IOH = – 1mA IOH = – 4mA ● ● 4.8 4.5 4.95 4.8 V V V + = 3V IOH = – 1mA IOH = – 4mA ● ● 2.7 2.2 2.9 2.6 V V V + = 5V IOL = 1mA IOL = 4mA ● ● 0.05 0.2 0.15 0.4 V V V + = 3V IOL = 1mA IOL = 4mA ● ● 0.1 0.4 0.3 0.7 V V V + = 5V Pin 4 = V+ or Floating, RL = ∞ Pin 4 = 0V, RL = ∞ 14 7 ns ns V + = 3V Pin 4 = V+ or Floating, RL = ∞ Pin 4 = 0V, RL = ∞ 19 11 ns ns V + = 5V Pin 4 = V+ or Floating, RL = ∞ Pin 4 = 0V, RL = ∞ 13 6 ns ns V + = 3V Pin 4 = V+ or Floating, RL = ∞ Pin 4 = 0V, RL = ∞ 19 10 ns ns VOL tr tf Low Level Output Voltage (Note 5) OUT Rise Time (Note 6) OUT Fall Time (Note 6) Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired. Note 2: Frequencies near 100kHz and 1MHz may be generated using two different values of RSET (see the Table 1 in the Applications Information section). For these frequencies, the error is specified under the following assumption: 10k < RSET ≤ 100k. The frequency accuracy for fOSC = 20MHz is guaranteed by design and test correlation. Note 3: Frequency accuracy is defined as the deviation from the fOSC equation. MIN TYP MAX UNITS Note 4: 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 5: 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 10% and 90% power supply levels. These specifications are based on characterization. Note 7: Guaranteed by 5V test. 3 LTC1799 U W TYPICAL PERFOR A CE CHARACTERISTICS Frequency Variation vs RSET Frequency Variation Over Temperature 4 1.00 TA = 25°C GUARANTEED LIMITS APPLY OVER 5k TO 200k RANGE 3 2 0.50 TYPICAL HIGH 1 VARIATION (%) VARIATION (%) RSET = 31.6k ÷1 OR ÷10 OR ÷100 0.75 0 TYPICAL LOW –1 0 –0.25 –2 –0.50 –3 –0.75 –4 1 10 100 TYPICAL HIGH 0.25 TYPICAL LOW –1.00 –40 1000 40 20 60 0 TEMPERATURE (°C) –20 RSET (kΩ) 1799 G01 1799 G02 Supply Current vs Output Frequency Peak-to-Peak Jitter vs Frequency 0.7 4.5 0.6 4.0 SUPPLY CURRENT (mA) ÷1 JITTER (%) 0.5 0.4 0.3 ÷10 0.2 ÷100 0.1 TA = 25°C CL = 5pF RL = 1M 3.5 3.0 ÷1 (5V) 2.5 ÷10 (5V) 2.0 ÷100 (5V) 1.5 1.0 ÷100 (3V) 0.5 0 ÷10 (3V) ÷1 (3V) 0 1k 100k 1M 10M 10k OUTPUT FREQUENCY, fOUT (Hz) 100M 1k 10k 100k 1M 10M OUTPUT FREQUENCY, fOUT (Hz) 1799 G03 Output Resistance vs Supply Voltage 140 OUTPUT RESISTANCE (Ω) 80 1799 G04 LTC1799 Output Operating at 20MHz, VS = 5V LTC1799 Output Operating at 10MHz, VS = 3V V + = 5V, RSET = 5k, CL = 10pF TA = 25°C 100M V + = 3V, RSET = 10k, CL = 10pF 120 OUTPUT SOURCING CURRENT 1V/DIV 100 1V/DIV 80 60 12.5ns/DIV OUTPUT SINKING CURRENT 40 2.5 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) 5.5 6.0 1799 G05 4 1799 G06 25ns/DIV 1799 G07 LTC1799 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 a ground plane with a 0.1µF capacitor. GND (Pin 2): Ground. Should be tied to a ground plane for best performance. SET (Pin 3): Frequency-Setting Resistor Input. The value of the resistor connected between this pin and V+ determines the oscillator frequency. The voltage on this pin is held by the LTC1799 to approximately 1.13V below the V+ voltage. For best performance, use a precision metal film resistor with a value between 10k and 200k and limit the capacitance on this pin to less than 10pF. DIV (Pin 4): Divider-Setting Input. This three-state input selects among three divider settings, determining the value of N in the frequency equation. Pin 4 should be tied to GND for the ÷1 setting, the highest frequency range. Floating Pin 4 divides the master oscillator by 10. Pin 4 should be tied to V+ for the ÷100 setting, the lowest frequency range. To detect a floating DIV pin, the LTC1799 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 5µA. Likewise, driving DIV low requires sinking 5µA. When Pin 4 is floated, preferably 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. OUT (Pin 5): Oscillator Output. This pin can drive 5kΩ and/or 10pF 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 OUT pin is limited to 50mA. W BLOCK DIAGRA 1 VRES = 1.13V ±25% (V+ – VSET) V+ PROGRAMMABLE DIVIDER (÷1, 10 OR 100) + RSET GAIN = 1 IRES 3 SET – + – 2 GND VBIAS IRES OUT 5 V+ MASTER OSCILLATOR ƒMO = 100MHz • kΩ • IRES (V + – VSET) DIVIDER SELECT 5µA DIV THREE-STATE INPUT DETECT 4 5µA GND 1799 BD 5 LTC1799 U THEORY OF OPERATIO As shown in the Block Diagram, the LTC1799’s master oscillator is controlled by the ratio of the voltage between the V+ and SET pins and the current entering the SET pin (IRES). The voltage on the SET pin is forced to approximately 1.13V below V+ 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 1). The effective input resistance is approximately 2k. A resistor RSET, connected between the V+ and SET pins, “locks together” the voltage (V + – VSET) and current, IRES, variation. This provides the LTC1799’s high precision. The master oscillation frequency reduces to: 10kΩ ƒMO = 10MHz • RSET The LTC1799 is optimized for use with resistors between 10k and 200k, corresponding to master oscillator frequencies between 0.5MHz and 10MHz. Accurate frequencies up to 20MHz (RSET = 5k) are attainable if the supply voltage is greater than 4V. To extend the output frequency range, the master oscillator signal may be divided by 1, 10 or 100 before driving 1.4 TA = 25°C OUT (Pin 5). The divide-by value is determined by the state of the DIV input (Pin 4). Tie DIV to GND or drive it below 0.5V to select ÷1. This is the highest frequency range, with the master output frequency passed directly to OUT. The DIV pin may be floated or driven to midsupply to select ÷10, the intermediate frequency range. The lowest frequency range, ÷100, is selected by tying DIV to V+ or driving it to within 0.4V of V+. Figure 2 shows the relationship between RSET, divider setting and output frequency, including the overlapping frequency ranges near 100kHz and 1MHz. The CMOS output driver has an on resistance that is typically less than 100Ω. In the ÷1 (high frequency) mode, the rise and fall times are typically 7ns with a 5V supply and 11ns with a 3V supply. These times maintain a clean square wave at 10MHz (20MHz at 5V supply). In the ÷10 and ÷100 modes, where the output frequency is much lower, slew rate control circuitry in the output driver increases the rise/fall times to typically 14ns for a 5V supply and 19ns for a 3V supply. The reduced slew rate lowers EMI (electromagnetic interference) and supply bounce. 1000 1.3 ÷100 100 1.2 RSET (kΩ) VRES = V + – VSET V + = 5V V + = 3V 1.1 1.0 ÷10 ÷1 MOST ACCURATE OPERATION 10 0.9 0.8 1 10 100 1000 IRES (µA) 1799 F01 Figure 1. V + – VSET Variation with IRES 6 1 1k 10k 100k 1M 10M DESIRED OUTPUT FREQUENCY (Hz) 100M 1799 F02 Figure 2. RSET vs Desired Output Frequency LTC1799 U W U U APPLICATIO S I FOR ATIO SELECTING THE DIVIDER SETTING AND RESISTOR The LTC1799’s master oscillator has a frequency range spanning 0.1MHz to 33MHz. However, accuracy may suffer if the master oscillator is operated at greater than 10MHz with a supply voltage lower than 4V. A programmable divider extends the frequency range to greater than three decades. Table 1 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 (fOSC) should be obtained using the lowest master oscillator frequency. Lower master oscillator frequencies use less power and are more accurate. For instance, fOSC = 100kHz can be obtained by either RSET = 10k, N = 100, master oscillator = 10MHz or RSET = 100k, N = 10, master oscillator = 1MHz. The RSET = 100k is preferred for lower power and better accuracy. Table 1. Frequency Range vs Divider Setting DIVIDER SETTING ÷1 ⇒ DIV (Pin 4) = GND ÷10 ⇒ DIV (Pin 4) = Floating ÷100 ⇒ DIV (Pin 4) = V+ FREQUENCY RANGE ALTERNATIVE METHODS OF SETTING THE OUTPUT FREQUENCY OF THE LTC1799 The oscillator may be programmed by any method that sources a current into the SET pin (Pin 3). The circuit in Figure 3 sets the oscillator frequency using a programmable current source and in the expression for fOSC, the resistor RSET is replaced by the ratio of 1.13V/ICONTROL. As already explained in the “Theory of Operation,” the voltage difference between V + and SET is approximately 1.13V, therefore, the Figure 3 circuit is less accurate than if a resistor controls the oscillator frequency. Figure 4 shows the LTC1799 configured as a VCO. A voltage source is connected in series with an external 10k resistor. The output frequency, fOSC, will vary with VCONTROL, that is the voltage source connected between V + and the SET pin. Again, this circuit decouples the relationship between the input current and the voltage between V + and SET; the frequency accuracy will be degraded. The oscillator frequency, however, will monotonically increase with decreasing VCONTROL. > 500kHz* 50kHz to 1MHz V 400kHz TO 21MHz (APPROXIMATE, SEE TEXT) + 1 < 100kHz *At master oscillator frequencies greater than 10MHz (R SET < 10kΩ), the LTC1799 may suffer reduced accuracy with a supply voltage less than 4V. 0.1µF ICONTROL 5µA TO 200µA 3 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. 100 10MHz RSET = 10k • , N = 10 N • fOSC 1 (RSETMIN = 3k (5V Supply), 5k (3V Supply), RSETMAX = 1M) Any resistor, RSET, tolerance adds to the inaccuracy of the oscillator, fOSC. 2 OUT V+ LTC1799 5 GND SET DIV 4 N=1 1799 F03 ƒOSC ≅ 10MHz • 10kΩ • ICONTROL N 1.13V ICONTROL EXPRESSED IN (A) Figure 3. Current Controlled Oscillator V+ VCONTROL 0V TO 1.13V + – 1 0.1µF RSET 10k 2 3 5 V+ OUT LTC1799 GND SET 4 DIV ( N=1 1799 F04 ƒOSC ≅ 10MHz • 10k • 1 – VCONTROL N RSET 1.13V ) Figure 4. Voltage Controlled Oscillator 7 LTC1799 U W U U APPLICATIO S I FOR ATIO POWER SUPPLY REJECTION START-UP TIME Low Frequency Supply Rejection (Voltage Coefficient) The start-up time and settling time to within 1% of the final value can be estimated by tSTART ≅ RSET(2.8µs/kΩ) + 20µs. Note the start-up time depends on RSET and it is independent from the setting of the divider pin. For instance with RSET = 50k, the LTC1799 will settle with 1% of its 200kHz final value (N = 10) in approximately 160µs. Figure 6 shows start-up times for various RSET resistors. Figure 5 shows the output frequency sensitivity to power supply voltage at several different temperatures. The LTC1799 has a conservative guaranteed voltage coefficient of 0.1%/V but, as Figure 5 shows, the typical supply sensitivity is lower. FREQUENCY DEVIATION (%) 0.15 Figure 7 shows an application where a second set resistor RSET2 is connected in parallel with set resistor RSET1 via switch S1. When switch S1 is open, the output frequency of the LTC1799 depends on the value of the resistor RSET1. When switch S1 is closed, the output frequency of the LTC1799 depends on the value of the parallel combination of RSET1 and RSET2. RSET = 31.6k PIN 4 = FLOATING (÷10) 0.10 25°C –40°C 0.05 85°C 0 –0.05 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 The start-up time and settling time of the LTC1799 with switch S1 open (or closed) is described by tSTART shown above. Once the LTC1799 starts and settles, and switch S1 closes (or opens), the LTC1799 will settle to its new output frequency within approximately 25µs. 1799 F05 Figure 5. Supply Sensitivity 60 TA = 25°C V + = 5V 50 FREQUENCY ERROR (%) High Frequency Power Supply Rejection The accuracy of the LTC1799 may be affected when its power supply generates significant noise with frequency contents in the vicinity of the programmed value of fOSC. If a switching power supply is used to power up the LTC1799, 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 LTC1799. Otherwise, the oscillator may show an additional 0.1% to 0.2% of frequency error. If the LTC1799 is powered by a switching regulator and the switching frequency or its harmonics coincide with the output frequency of the LTC1799, the jitter of the oscillator output may be affected. This phenomenon will become noticeable if the switching regulator exhibits ripples beyond 30mV. 40 30 20 200k 10 10k 31.6k 0 –10 400 300 500 100 200 TIME AFTER POWER APPLIED (µs) 0 1799 F06 Figure 6. Start-Up Time 3V OR 5V S1 RSET1 RSET2 1 2 V+ OUT 5 fOSC = 10MHz • OR LTC1799 V+ GND 3 SET DIV 4 fOSC = 10MHz • ÷100 ÷10 ÷1 1799 F07 Figure 7 8 600 ( ( ) 10k N • RSET1 10k N • RSET1//RSET2 ) LTC1799 U W U U APPLICATIO S I FOR ATIO Jitter 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 3) is limited to less than 10pF, 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. U TYPICAL APPLICATIO S Low Power 80Hz to 8kHz Sine Wave Generator (IQ < 4mA) 3V 1 C1 0.1µF RSET 2 3 V+ OUT LTC1799 GND SET DIV fOSC 5 3V 3V, N = 100 SW1 OPEN, N = 10 4 C4 1µF 74HC4520 1 3V 2 16 C2 0.1µF 10 7 8 800Hz ≤ fSINE ≤ 8kHz, N = 10 80Hz ≤ fSINE ≤ 800Hz, N = 100 9 15 CLOCK A Q1A ENABLE A Q2A VDD Q3A ENABLE B Q4A RESET A Q1B VSS Q2B CLOCK B Q3B RESET B Q4B 3 ÷2 4 ÷4 5 ÷8 6 ÷16 11 ÷32 12 ÷64 1 2 3 R61 10k 4 R51 5.11k R31 51.1k R11 100k 13 ÷128 14 ÷256 LTC1067-50 3V C3 0.1µF 5 6 7 R21 20k 8 V+ CLK NC AGND V+ V– SA SB LPA LPB BPA BPB HPA/NA HPB/NB INV A INV B 16 15 14 R62 14k 13 R52 5.11k 12 11 R32 51.1k fSINE = 10MHz • 10k N 64RSET 10 9 SINEWAVE OUT R22 20k RH1 249k fOSC 64 RL1 51.1k 1799 TA05 CLOCK-TUNABLE LOWPASS FILTER WITH A STOPBAND NOTCH AT THE 3rd HARMONIC fOSC •3 64 ( ) 9 LTC1799 U TYPICAL APPLICATIO S 3V Digitally Controlled Oscillator with 5kHz to 85kHz Range (N = 100, Pin 4 = V +) 3V LTC1659 CLK DIN CS/LD 1 2 3 4 CLK VCC DIN VOUT CS/LD REF DOUT GND C3 0.1µF 8 7 3V 6 5 R5 10k R6 10k 3V R1 10k R2 10k 10 + 1/4 LT1491 9 C2 0.1µF 3 + 4 1 1/4 LT1491 2 – 11 5kHz TO 85kHz R8 10k 8 – RS 10k R7 10k R4 10k R3 10k 7 + 3 6 I= (V + – VSET) C • 10k 4096 Input Code vs Output Frequency (N = 100, Pin 4 = V +) 100 fOUT (kHz) 75 50 25 0 1024 2048 DAC CODE 3072 4096 1799 TA07 10 V+ OUT LTC1799 5 fOSC = 100kHz • GND SET OUT DIV 4 3V 1799 TA06 NOTES: 1. FOR N = 10 (PIN 4 OPEN) THE RANGE IS 50kHz TO 850kHz 2. FOR N = 1 (PIN 4 = GND) THE RANGE IS 500kHz TO 8.5MHz 3. DRIVING PIN 4 OF THE LTC1799 WITH A 3-STATE LOGIC DEVICE GIVES A RANGE OF 5kHz TO 8.5MHz 0 1 C1 0.1µF 2 5 1/4 LT1491 – 3V C: DAC CODE 200 ≤ C ≤ 3480 C 4096 LTC1799 U PACKAGE DESCRIPTIO S5 Package 5-Lead Plastic SOT-23 (Reference LTC DWG # 05-08-1633) (Reference LTC DWG # 05-08-1635) 2.80 – 3.10 (.110 – .118) (NOTE 3) A SOT-23 (Original) .90 – 1.45 (.035 – .057) SOT-23 (ThinSOT) 1.00 MAX (.039 MAX) A1 .00 – .15 (.00 – .006) .01 – .10 (.0004 – .004) A2 .90 – 1.30 (.035 – .051) .80 – .90 (.031 – .035) L .35 – .55 (.014 – .021) .30 – .50 REF (.012 – .019 REF) 2.60 – 3.00 (.102 – .118) 1.50 – 1.75 (.059 – .069) (NOTE 3) PIN ONE .95 (.037) REF .25 – .50 (.010 – .020) (5PLCS, NOTE 2) .20 (.008) A DATUM ‘A’ L NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) .09 – .20 (.004 – .008) (NOTE 2) A2 1.90 (.074) REF A1 S5 SOT-23 0401 3. DRAWING NOT TO SCALE 4. DIMENSIONS ARE INCLUSIVE OF PLATING 5. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 6. MOLD FLASH SHALL NOT EXCEED .254mm 7. PACKAGE EIAJ REFERENCE IS: SC-74A (EIAJ) FOR ORIGINAL JEDEL MO-193 FOR THIN 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 LTC1799 U TYPICAL APPLICATIO S Shutting Down the LTC1799 5V 74AC04 1 ON/SHDN R1 10k C1 0.1µF 2 3 5 V+ OUT LTC1799 OUT GND SET 4 DIV 1799 TA08 Temperature-to-Frequency Converter Output Frequency vs Temperature 1400 RT 100k THERMISTOR 1 C1 0.1µF 2 3 OUT V+ LTC1799 5 GND SET DIV 4 1799 TA03 RT: YSI 44011 800 765-4974 MAX TYP MIN 1200 fOSC = 10MHz • 10k RT 10 FREQUENCY (kHz) 5V 1000 800 600 400 200 0 –20 –10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (°C) 1799 TA04 12 Linear Technology Corporation 1799f LT/TP 0801 2K • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2001