1.8 V Low Power CMOS Rail-to-Rail Input/Output Operational Amplifier AD8515 Single-supply operation: 1.8 V to 5 V Offset voltage: 6 mV maximum Space-saving SOT-23 and SC70 packages Slew rate: 2.7 V/μs Bandwidth: 5 MHz Rail-to-rail input and output swing Low input bias current: 2 pA typical Low supply current @ 1.8 V: 450 μA maximum PIN CONFIGURATION OUT 1 V– 2 5 V+ AD8515 TOP VIEW +IN 3 (Not to Scale) 4 –IN 03024-001 FEATURES Figure 1. 5-Lead SC70 and 5-Lead SOT-23 (KS and RJ Suffixes) APPLICATIONS Portable communications Portable phones Sensor interfaces Laser scanners PCMCIA cards Battery-powered devices New generation phones Personal digital assistants GENERAL DESCRIPTION The AD8515 is a rail-to-rail amplifier that can operate from a single-supply voltage as low as 1.8 V. The AD8515 single amplifier, available in 5-lead SOT-23 and 5-lead SC70 packages, is small enough to be placed next to sensors, reducing external noise pickup. The AD8515 is a rail-to-rail input and output amplifier with a gain bandwidth of 5 MHz and typical offset voltage of 1 mV from a 1.8 V supply. The low supply current makes these parts ideal for battery-powered applications. The 2.7 V/μs slew rate makes the AD8515 a good match for driving ASIC inputs such as voice codecs. The AD8515 is specified over the extended industrial temperature range of −40°C to +125°C. Rev. D Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2002–2007 Analog Devices, Inc. All rights reserved. AD8515 TABLE OF CONTENTS Features .............................................................................................. 1 Typical Performance Characteristics ..............................................7 Applications....................................................................................... 1 Theory of Operation ...................................................................... 12 Pin Configuration............................................................................. 1 Power Consumption vs. Bandwidth ........................................ 12 General Description ......................................................................... 1 Driving Capacitive Loads .............................................................. 13 Revision History ............................................................................... 2 Full Power Bandwidth ............................................................... 13 Specifications..................................................................................... 3 A Micropower Reference Voltage Generator.............................. 14 Electrical Characteristics............................................................. 3 A 100 kHz Single-Supply Second-Order Band-Pass Filter ... 14 Absolute Maximum Ratings............................................................ 6 Wien Bridge Oscillator .............................................................. 15 Thermal Resistance ...................................................................... 6 Outline Dimensions ....................................................................... 16 ESD Caution.................................................................................. 6 Ordering Guide .......................................................................... 16 REVISION HISTORY 7/07—Rev. C to Rev. D 2/03—Rev. 0 to Rev. A Updated Format..................................................................Universal Updated Package Designator Throughout.................................... 1 Changes to Table 1, Supply Current/Amplifier ............................ 3 Changes to Table 2, Supply Current/Amplifier ............................ 4 Changes to Table 3, Large Signal Voltage Gain, Power Supply Rejection Ratio, and Supply Current/Amplifier........................... 5 Changes to Figure 10........................................................................ 8 Changes to Figure 35...................................................................... 14 Updated Outline Dimensions ....................................................... 16 Changes to Ordering Guide .......................................................... 16 4/03—Rev. A to Rev. B Added new SC70 Package .................................................Universal Changes to Features ..........................................................................1 Changes to General Description .....................................................1 Changes to Pin Configuration .........................................................1 Changes to Specifications.................................................................2 Changes to Absolute Maximum Ratings........................................5 Changes to Ordering Guide .............................................................5 Changes to TPC 3..............................................................................6 Changes to TPC 10............................................................................7 Changes to TPC 13............................................................................8 Changes to TPC 27......................................................................... 10 Changes to TPC 28......................................................................... 10 Added new TPC 29 ........................................................................ 10 Changes to Functional Description ............................................. 11 Updated to Outline Dimensions .................................................. 14 Change to Figure 5 ......................................................................... 12 8/02—Revision. 0: Initial Version 3/05—Rev. B to Rev. C Changes to Specifications ................................................................ 2 Changes to Ordering Guide ............................................................ 5 Rev. D | Page 2 of 16 AD8515 SPECIFICATIONS ELECTRICAL CHARACTERISTICS VS = 1.8 V, VCM = VS/2, TA = 25°C, unless otherwise noted. Table 1. Parameter INPUT CHARACTERISTICS Symbol Conditions Offset Voltage VOS Input Bias Current IB VCM = VS/2 −40°C < TA < +125°C VS = 1.8 V −40°C < TA < +85°C −40°C < TA < +125°C Input Offset Current IOS Min Typ Max Unit 1 6 8 30 600 8 10 500 1.8 400 4 mV mV pA pA nA pA pA V dB dB V/mV μV/°C 20 V V mV mV mA 2 1 −40°C < TA < +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low Short Circuit Limit POWER SUPPLY Supply Current/Amplifier CMRR AVO ΔVOS/ΔT VOH VOL 0 V ≤ VCM ≤ 1.8 V −40°C < TA < +125°C RL = 100 kΩ, 0.3 V ≤ VOUT ≤ 1.5 V IL = 100 μA, −40°C < TA < +125°C IL = 750 μA, −40°C < TA < +125°C IL = 100 μA, −40°C < TA < +125°C IL = 750 μA, −40°C < TA < +125°C ISC 0 50 47 110 1.79 1.77 10 30 ISY VOUT = VS/2 –40°C < TA < +125°C 325 450 500 μA μA DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Density SR GBP RL = 10 kΩ 2.7 5 V/μs MHz en Current Noise Density in f = 1 kHz f = 10 kHz f = 1 kHz 22 20 0.05 nV/√Hz nV/√Hz pA/√Hz Rev. D | Page 3 of 16 AD8515 VS = 3.0 V, VCM = VS/2, TA = 25°C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Symbol Conditions Offset Voltage VOS Input Bias Current IB VCM = VS/2 −40°C < TA < +125°C VS = 3.0 V −40°C < TA < +85°C −40°C < TA < +125°C Input Offset Current IOS Min Typ Max Unit 1 6 8 30 600 8 10 500 3 mV mV pA pA nA pA pA V dB dB V/mV μV/°C 2 1 −40°C < TA < +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier CMRR AVO ΔVOS/ΔT VOH VOL PSRR ISY 0 V ≤ VCM ≤ 3.0 V −40°C < TA < +125°C RL = 100 kΩ, 0.3 V ≤ VOUT ≤ 2.7 V 0 54 50 250 IL = 100 μA, −40°C < TA < +125°C IL = 750 μA, −40°C < TA < +125°C IL = 100 μA, −40°C < TA < +125°C IL = 750 μA, −40°C < TA < +125°C 2.99 2.98 VS = 1.8 V to 5.0 V −40°C < TA < +125°C VOUT = VS/2 −40°C < TA < +125°C 65 57 1000 4 85 80 350 10 20 V V mV mV 450 500 dB dB μA μA DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Density SR GBP RL = 10 kΩ 2.7 5 V/μs MHz en Current Noise Density in f = 1 kHz f = 10 kHz f = 1 kHz 22 20 0.05 nV/√Hz nV/√Hz pA/√Hz Rev. D | Page 4 of 16 AD8515 VS = 5.0 V, VCM = VS/2, TA = 25°C, unless otherwise noted. Table 3. Parameter INPUT CHARACTERISTICS Symbol Conditions Offset Voltage VOS Input Bias Current IB VCM = VS/2 –40°C < TA < +125°C VS = 5.0 V –40°C < TA < +85°C –40°C < TA < +125°C Input Offset Current IOS Min Typ Max Unit 1 6 8 30 600 8 10 500 5.0 mV mV pA pA nA pA pA V dB dB V/mV μV/°C 5 1 –40°C < TA < +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage High Output Voltage Low POWER SUPPLY Power Supply Rejection Ratio Supply Current/Amplifier CMRR AVO ΔVOS/ΔT VOH VOL PSRR ISY 0 V ≤ VCM ≤ 5.0 V –40°C < TA < +125°C RL = 100 kΩ, 0.3 V ≤ VOUT ≤ 4.7 V IL = 100 μA, –40°C < TA < +125°C IL = 750 μA, –40°C < TA < +125°C IL = 100 μA, –40°C < TA < +125°C IL = 750 μA, –40°C < TA < +125°C VS = 1.8 V to 5.0 V –40°C < TA < +125°C VOUT = VS/2 –40°C < TA < +125°C 0 60 54 450 75 2000 4 4.99 4.98 65 57 85 80 410 10 20 V V mV mV 550 600 dB dB μA μA DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Density SR GBP RL = 10 kΩ 2.7 5 V/μs MHz en Current Noise Density in f = 1 kHz f = 10 kHz f = 1 kHz 22 20 0.05 nV/√Hz nV/√Hz pA/√Hz Rev. D | Page 5 of 16 AD8515 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. THERMAL RESISTANCE Table 4. Parameter Supply Voltage Input Voltage Differential Input Voltage Output Short-Circuit Duration to GND Storage Temperature Range KS and RJ Packages Operating Temperature Range AD8515 Junction Temperature Range KS and RJ Packages Lead Temperature (Soldering, 60 sec) Rating 6V GND to VS ±6 V or ±VS Observe derating curves −65°C to +150°C −40°C to +125°C θJA is specified for the worst-case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 5. Thermal Resistance Package Type 5-Lead SOT-23 (RJ) 5-Lead SC70 (KS) ESD CAUTION −65°C to +150°C 300°C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rev. D | Page 6 of 16 θJA 230 376 θJC 146 126 Unit °C/W °C/W AD8515 TYPICAL PERFORMANCE CHARACTERISTICS 450 6 VS = ±2.5V 5 SUPPLY VOLTAGE (V) 350 300 4 3 2 250 200 4.65 03024-002 1 4.70 4.75 4.80 4.85 4.90 0 4.65 4.95 03024-005 SUPPLY CURRENT (µA) 400 4.70 4.75 BANDWIDTH (MHz) 4.80 4.85 4.95 4.90 BANDWIDTH (MHz) Figure 2. Supply Current vs. Bandwidth Figure 5. Supply Voltage vs. Bandwidth 450 160 400 140 VS = ±2.5V 300 250 200 150 100 80 60 40 0 1 2 3 4 5 0 6 03024-006 20 0 5 SUPPLY VOLTAGE (V) 10 Figure 3. Supply Current vs. Supply Voltage Figure 6. Output Voltage to Supply Rail vs. Load Current 500 270 120 VS = 5V 100 VS = ±2.5V AMPLITUDE = 20mV 225 180 80 450 GAIN (dB) 60 400 40 GAIN 135 90 PHASE 20 45 0 0 –20 –45 –40 –90 –60 –135 300 –50 –25 0 25 50 75 100 125 –80 1k 150 TEMPERATURE (°C) 10k 100k 1M 10M FREQUENCY (Hz) Figure 4. ISY vs. Temperature Figure 7. Gain and Phase vs. Frequency Rev. D | Page 7 of 16 –180 50M 03024-007 350 03024-004 ISY (µA) 20 15 LOAD CURRENT (mA) PHASE (DEGREES) 0 VOH 100 03024-003 50 VOL 120 ΔOUTPUT VOLTAGE (mV) SUPPLY CURRENT (µA) 350 AD8515 120 100 96 VS = ±2.5V VS = ±2.5V 80 92 40 20 0 G = 100 PSRR (dB) ACL (dB) 60 G = 10 G=1 88 84 –20 –40 –60 –80 10k 100k 1M 10M 03024-011 03024-008 80 76 –50 30M 0 FREQUENCY (Hz) Figure 8. ACL vs. Frequency Figure 11. PSRR vs. Temperature 430 VS = ±2.5V AMPLITUDE = 50mV VS = ±2.5V 80 NUMBER OF AMPLIFIERS 344 CMRR (dB) 60 40 20 0 –20 –40 258 172 03024-009 86 –60 –80 10k 100k 1M 0 –6.24 100M 10M –4.27 FREQUENCY (Hz) 1.66 3.63 150 VS = ±2.5V AMPLITUDE = 50mV 120 100 VS = ±2.5V OUTPUT IMPEDANCE (Ω) +PSRR 80 –PSRR 40 20 0 1k 10k 100k 100 50 GAIN = 100 03024-010 PSRR (dB) –0.32 Figure 12. VOS Distribution 140 –20 100 –2.29 VOS (mV) Figure 9. CMRR vs. Frequency 60 150 03024-012 100 100 0 1k 1M FREQUENCY (Hz) 10k GAIN = 10 GAIN = 1 100k 1M FREQUENCY (Hz) Figure 10. PSRR vs. Frequency Figure 13. Output Impedance vs. Frequency Rev. D | Page 8 of 16 03024-013 120 50 TEMPERATURE (°C) 10M AD8515 25 VS = ±2.5V VIN = 6.4V VS = 5V 24 ISC (mA) 22 VOLTAGE (2V/DIV) 23 –ISC 21 20 +ISC 19 VIN VOUT 18 03024-014 03024-017 17 16 15 –50 0 50 150 100 TIME (200µs/DIV) TEMPERATURE (°C) Figure 14. ISC vs. Temperature Figure 17. No Phase Reversal VS = ±2.5V 0 250 500 750 1k 1.25k 1.5k 1.75k 2k 03024-018 03024-015 VOLTAGE (13µV/DIV) VOLTAGE (100mV/DIV) VS = ±2.5V CL = 50pF VIN = 200mV 2.25k 2.5k FREQUENCY (Hz) TIME (1µs/DIV) Figure 15. Voltage Noise Density Figure 18. Small Signal Transient Response VS = ±2.5V GAIN = 100 03024-019 VOLTAGE (100mV/DIV) 03024-016 VOLTAGE (200mV/DIV) VS = ±2.5V CL = 500pF VIN = 200mV TIME (1s/DIV) TIME (1µs/DIV) Figure 19. Small Signal Transient Response Figure 16. Input Voltage Noise Rev. D | Page 9 of 16 AD8515 120 VS = ±2.5V CL = 300pF VIN = 4V 100 VS = ±1.5V AMPLITUDE = 50mV 80 40 CMRR (dB) VOLTAGE (1V/DIV) 60 20 0 –20 03024-023 03024-020 –40 –60 –80 10k 100k TIME (1µs/DIV) Figure 20. Large Signal Transient Response 100M VS = ±0.9V CL = 50pF VIN = 200mV VOLTAGE (100mV/DIV) 0V 0V 2V 03024-024 03024-021 VOUT TIME (2µs/DIV) TIME (1µs/DIV) 0V VS = ±1.5V GAIN = –40 VIN = 100mV Figure 24. Small Signal Transient Response 270 120 VIN 100 VS = ±0.9V AMPLITUDE = 20mV 225 80 180 60 135 40 90 20 45 0 0 GAIN (dB) 2V VOUT 0V 03024-022 VOLTAGE –100mV TIME (2µs/DIV) –20 –45 –40 –90 –60 –135 –80 10k 100k 1M 10M FREQUENCY (Hz) Figure 25. Gain and Phase vs. Frequency Figure 22. Saturation Recovery Rev. D | Page 10 of 16 –180 30M PHASE (DEGREES) Figure 21. Saturation Recovery 03024-025 VOLTAGE 10M Figure 23. CMRR vs. Frequency VS = ±1.5V GAIN = –40 VIN = 100mV VIN 100mV 1M FREQUENCY (Hz) AD8515 200 4.995 VS = ±0.9V VS = 5V IL = 750µA VOH (V) 4.993 100 4.992 50 0 1k 10k 4.991 GAIN = 10 GAIN = 1 100k 1M 4.990 –50 10M 03024-029 GAIN = 100 03024-026 OUTPUT IMPEDANCE (Ω) 4.994 150 0 FREQUENCY (Hz) 50 Figure 26. Output Impedance vs. Frequency Figure 29. VOH vs. Temperature 80 VS = ±0.9V VS = 5V VIN = 3.2V 77 CMRR (dB) VIN VOLTAGE (1V/DIV) 150 100 TEMPERATURE (°C) VOUT 74 71 65 –50 TIME (200µs/DIV) VS = 5V IL = 750µA 7 5 03024-028 VOL (mV) 9 50 50 100 Figure 30. CMRR vs. Temperature 11 0 0 TEMPERATURE (°C) Figure 27. No Phase Reversal 3 –50 03024-030 03024-027 68 100 150 TEMPERATURE (°C) Figure 28. VOL vs. Temperature Rev. D | Page 11 of 16 150 AD8515 THEORY OF OPERATION The AD8515, offered in space-saving SOT-23 and SC70 packages, is a rail-to-rail input and output operational amplifier that can operate at supply voltages as low as 1.8 V. This product is fabricated using 0.6 micron CMOS to achieve one of the best power consumption-to-speed ratios (that is, bandwidth) in the industry. With a small amount of supply current (less than 400 μA), a wide unity gain bandwidth of 4.5 MHz is available for signal processing. The input stage consists of two parallel, complementary, differential pairs of PMOS and NMOS. The AD8515 exhibits no phase reversal because the input signal exceeds the supply by more than 0.6 V. Currents into the input pin must be limited to 5 mA or less by the use of external series resistance(s). The AD8515 has a very robust ESD design and can stand ESD voltages of up to 4000 V. POWER CONSUMPTION vs. BANDWIDTH This product solves the speed/power requirements for many applications. The wide bandwidth is also stable even when operated with low supply voltages. Figure 5 shows the relationship between the supply voltage vs. the bandwidth for the AD8515. The AD8515 is ideal for battery-powered instrumentation and handheld devices because it can operate at the end of discharge voltage of most popular batteries. Table 6 lists the nominal and end of discharge voltages of several typical batteries. Table 6. Typical Battery Life Voltage Range Battery Lead-Acid Lithium NiMH NiCd Carbon-Zinc One of the strongest features of the AD8515 is the bandwidth stability over the specified temperature range while consuming small amounts of current. This effect is shown in Figure 2 through Figure 4. Rev. D | Page 12 of 16 Nominal Voltage (V) 2 2.6 to 3.6 1.2 1.2 1.5 End of Discharge Voltage (V) 1.8 1.7 to 2.4 1 1 1.1 AD8515 DRIVING CAPACITIVE LOADS The AD8515 is even capable of driving higher capacitive loads in inverting gain of −1, as shown in Figure 33. VS = ±2.5V CL = 50pF GAIN = 1 VS = ±0.9V CL = 800pF GAIN = –1 03024-033 VOLTAGE (100mV/DIV) Most amplifiers have difficulty driving large capacitive loads. Additionally, higher capacitance at the output can increase the amount of overshoot and ringing in the amplifier’s step response and can even affect the stability of the device. This is due to the degradation of phase margin caused by additional phase lag from the capacitive load. The value of capacitive load that an amplifier can drive before oscillation varies with gain, supply voltage, input signal, temperature, and other parameters. Unity gain is the most challenging configuration for driving capacitive loads. The AD8515 is capable of driving large capacitive loads without any external compensation. The graphs in Figure 31 and Figure 32 show the amplifier’s capacitive load driving capability when configured in unity gain of +1. TIME (1µs/DIV) Figure 33. Capacitive Load Driving @ CL = 800 pF FULL POWER BANDWIDTH VOLTAGE (100mV/DIV) The slew rate of an amplifier determines the maximum frequency at which it can respond to a large input signal. This frequency (known as full power bandwidth, FPBW) can be calculated from the equation FPBW = SR 2π × V PEAK 03024-031 for a given distortion. The FPBW of the AD8515 is shown in Figure 34 to be close to 200 kHz. VIN VOLTAGE (2V/DIV) TIME (1µs/DIV) Figure 31. Capacitive Load Driving @ CL = 50 pF VS = ±2.5V CL = 500pF GAIN = 1 03024-034 VOLTAGE (10mV/DIV) VOUT TIME (2µs/DIV) 03024-032 Figure 34. Full Power Bandwidth TIME (1µs/DIV) Figure 32. Capacitive Load Driving @ CL = 500 pF Rev. D | Page 13 of 16 AD8515 A MICROPOWER REFERENCE VOLTAGE GENERATOR Many single-supply circuits are configured with the circuit biased to one-half of the supply voltage. In these cases, a false ground reference can be created by using a voltage divider buffered by an amplifier. Figure 35 shows the schematic for such a circuit. The two 1 MΩ resistors generate the reference voltages while drawing only 0.9 μA of current from a 1.8 V supply. A capacitor connected from the inverting terminal to the output of the op amp provides compensation to allow for a bypass capacitor to be connected at the reference output. This bypass capacitor helps establish an ac ground for the reference output. 1.8V TO 5V C3 1µF R1 1MΩ 3 4 + – U1 V+ V– 1 AD8515 R4 100Ω 1 2 π × R1 × C1 fH = 1 2 π × R1 × C1 H0 = 1 + R1 R2 VCC = 1.8 V − 5 V where: fL is the low −3 dB frequency. fH is the high −3 dB frequency. H0 is the midfrequency gain. VCC VCC 0.9V TO 2.5V C1 1µF R6 1MΩ 3 V11 C2 0.022µF 400mV 03024-035 R3 10kΩ R5 2kΩ 4 – C1 2nF R8 1MΩ C3 1µF + R1 5kΩ U9 V+ V– VOUT 1 AD8515 0 R2 20kΩ Figure 35. Micropower Voltage Reference Generator A 100 kHz SINGLE-SUPPLY SECOND-ORDER BAND-PASS FILTER C6 10pF 0 Figure 36. Second-Order Band-Pass Filter 2 A common-mode bias level is easily created by connecting the noninverting input to a resistor divider consisting of two resistors connected between VCC and ground. This bias point is also decoupled to ground with a 1 μF capacitor. Rev. D | Page 14 of 16 1.5 1 0.5 0 1k 03024-037 OUTPUT VOLTAGE (V) The circuit in Figure 36 is commonly used in portable applications where low power consumption and wide bandwidth are required. This figure shows a circuit for a single-supply band-pass filter with a center frequency of 100 kHz. It is essential that the op amp have a loop gain at 100 kHz to maintain an accurate center frequency. This loop gain requirement necessitates the choice of an op amp with a high unity gain crossover frequency, such as the AD8515. The 4.5 MHz bandwidth of the AD8515 is sufficient to accurately produce the 100 kHz center frequency, as the response in Figure 37 shows. When the op amp bandwidth is close to the center frequency of the filter, the amplifier internal phase shift causes excess phase shift at 100 kHz, altering the filter response. In fact, if the chosen op amp has a bandwidth close to 100 kHz, the phase shift of the op amps causes the loop to oscillate. 03024-036 R2 1MΩ fL = 10k 100k 1M 10M FREQUENCY (Hz) Figure 37. Frequency Response of the Band-Pass Filter 100M AD8515 The circuit in Figure 38 can be used to generate a sine wave, one of the most fundamental waveforms. Known as a Wien Bridge oscillator, it has the advantage of requiring only one low power amplifier. This is an important consideration, especially for batteryoperated applications where power consumption is a critical issue. To keep the equations simple, the resistor and capacitor values used are kept equal. For the oscillation to happen, two conditions have to be met. First, there should be a zero phase shift from the input to the output, which happens at the oscillation frequency of fOSC = High frequency oscillators can be built with the AD8515, due to its wide bandwidth. Using the values shown, an oscillation frequency of 130 kHz is created and is shown in Figure 39. If R11 is too low, the oscillation might converge; if too large, the oscillation diverges until the output clips (VS = ±2.5 V, fOSC = 130 kHz). 1 2 πR10 × C10 C9 1nF 03024-039 Second, at this frequency, the ratio of VOUT to the voltage at the positive input (+IN, Pin 3) has to be 3, which means that the ratio of R11:R12 should be greater than 2. R19 1kΩ Figure 39. Output of Wien Bridge Oscillator VCC 3 R13 1kΩ – U10 V+ V– 1 AD8515 VEE R12 1kΩ R11 2.05kΩ 03024-038 C10 1nF 2 + VOLTAGE (2V/DIV) WIEN BRIDGE OSCILLATOR Figure 38. Low Power Wien Bridge Oscillator Rev. D | Page 15 of 16 AD8515 OUTLINE DIMENSIONS 2.90 BSC 5 4 2.80 BSC 1.60 BSC 1 2 3 PIN 1 0.95 BSC 1.90 BSC 1.30 1.15 0.90 1.45 MAX 0.15 MAX 0.50 0.30 0.22 0.08 10° 5° 0° SEATING PLANE 0.60 0.45 0.30 COMPLIANT TO JEDEC STANDARDS MO-178-A A Figure 40. 5-Lead Small Outline Transistor Package [SOT-23] (RJ-5) Dimensions shown in millimeters 2.20 2.00 1.80 1.35 1.25 1.15 5 1 4 2 3 PIN 1 2.40 2.10 1.80 0.65 BSC 1.00 0.90 0.70 1.10 0.80 0.30 0.15 0.10 MAX 0.40 0.10 SEATING PLANE 0.22 0.08 0.46 0.36 0.26 0.10 COPLANARITY COMPLIANT TO JEDEC STANDARDS MO-203-AA Figure 41. 5-Lead Thin Shrink Small Outline Transistor Package [SC70] (KS-5) Dimensions shown in millimeters ORDERING GUIDE Model AD8515ART-R2 AD8515ART-REEL AD8515ART-REEL7 AD8515ARTZ-R2 1 AD8515ARTZ-REEL1 AD8515ARTZ-REEL71 AD8515AKS-R2 AD8515AKS-REEL AD8515AKS-REEL7 AD8515AKSZ-R21 AD8515AKSZ-REEL1 AD8515AKSZ-REEL71 1 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C Package Description 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 5-Lead SOT-23 5-Lead SC70 5-Lead SC70 5-Lead SC70 5-Lead SC70 5-Lead SC70 5-Lead SC70 Z = RoHS Compliant Part; # denotes RoHS product, may be top or bottom marked. ©2002–2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03024-0-7/07(D) Rev. D | Page 16 of 16 Package Option RJ-5 RJ-5 RJ-5 RJ-5 RJ-5 RJ-5 KS-5 KS-5 KS-5 KS-5 KS-5 KS-5 Branding BDA BDA BDA BDA# BDA# BDA# BDA BDA BDA BDA# BDA# BDA#