AD8515

1.8 V Low Power CMOS Rail-to-Rail Input/Output Operational Amplifier AD8515 FEATURES 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 03024-001 TOP VIEW +IN 3 (Not to Scale) 4 –IN 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 Applications....................................................................................... 1 Pin Configuration............................................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Electrical Characteristics............................................................. 3 Absolute Maximum Ratings............................................................ 6 Thermal Resistance ...................................................................... 6 ESD Caution.................................................................................. 6 Typical Performance Characteristics ..............................................7 Theory of Operation ...................................................................... 12 Power Consumption vs. Bandwidth ........................................ 12 Driving Capacitive Loads .............................................................. 13 Full Power Bandwidth ............................................................... 13 A Micropower Reference Voltage Generator.............................. 14 A 100 kHz Single-Supply Second-Order Band-Pass Filter ... 14 Wien Bridge Oscillator .............................................................. 15 Outline Dimensions ....................................................................... 16 Ordering Guide .......................................................................... 16 REVISION HISTORY 7/07—Rev. C to Rev. D 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 3/05—Rev. B to Rev. C Changes to Specifications ................................................................ 2 Changes to Ordering Guide ............................................................ 5 4/03—Rev. A to Rev. B Change to Figure 5 ......................................................................... 12 2/03—Rev. 0 to Rev. A 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 8/02—Revision. 0: Initial Version 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 Offset Voltage Input Bias Current Symbol VOS IB Conditions VCM = VS/2 −40°C < TA < +125°C VS = 1.8 V −40°C < TA < +85°C −40°C < TA < +125°C −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 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Density Current Noise Density CMRR AVO ΔVOS/ΔT VOH VOL ISC ISY VOUT = VS/2 –40°C < TA < +125°C RL = 10 kΩ 0 V ≤ VCM ≤ 1.8 V −40°C < TA < +125°C RL = 100 kΩ, 0.3 V ≤ VOUT ≤ 1.5 V 0 50 47 110 Min Typ 1 2 Max 6 8 30 600 8 10 500 1.8 Unit mV mV pA pA nA pA pA V dB dB V/mV μV/°C V V mV mV mA μA μA V/μs MHz nV/√Hz nV/√Hz pA/√Hz Input Offset Current IOS 1 400 4 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 1.79 1.77 10 30 20 325 450 500 SR GBP en in 2.7 5 22 20 0.05 f = 1 kHz f = 10 kHz f = 1 kHz 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 Offset Voltage Input Bias Current Symbol VOS IB Conditions VCM = VS/2 −40°C < TA < +125°C VS = 3.0 V −40°C < TA < +85°C −40°C < TA < +125°C −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 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Density Current Noise Density CMRR AVO ΔVOS/ΔT VOH VOL 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 Min Typ 1 2 Max 6 8 30 600 8 10 500 3 Unit mV mV pA pA nA pA pA V dB dB V/mV μV/°C V V mV mV dB dB μA μA V/μs MHz nV/√Hz nV/√Hz pA/√Hz Input Offset Current IOS 1 1000 4 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 RL = 10 kΩ 2.99 2.98 10 20 65 57 85 80 350 PSRR ISY 450 500 SR GBP en in 2.7 5 22 20 0.05 f = 1 kHz f = 10 kHz f = 1 kHz 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 Offset Voltage Input Bias Current Symbol VOS IB Conditions VCM = VS/2 –40°C < TA < +125°C VS = 5.0 V –40°C < TA < +85°C –40°C < TA < +125°C –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 DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product NOISE PERFORMANCE Voltage Noise Density Current Noise Density CMRR AVO ΔVOS/ΔT VOH VOL 0 V ≤ VCM ≤ 5.0 V –40°C < TA < +125°C RL = 100 kΩ, 0.3 V ≤ VOUT ≤ 4.7 V 0 60 54 450 4.99 4.98 10 20 65 57 85 80 410 75 2000 4 Min Typ 1 5 Max 6 8 30 600 8 10 500 5.0 Unit mV mV pA pA nA pA pA V dB dB V/mV μV/°C V V mV mV dB dB μA μA V/μs MHz nV/√Hz nV/√Hz pA/√Hz Input Offset Current IOS 1 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 RL = 10 kΩ PSRR ISY 550 600 SR GBP en in 2.7 5 22 20 0.05 f = 1 kHz f = 10 kHz f = 1 kHz Rev. D | Page 5 of 16 AD8515 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. 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 −65°C to +150°C 300°C THERMAL RESISTANCE 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) θJA 230 376 θJC 146 126 Unit °C/W °C/W ESD CAUTION 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 AD8515 TYPICAL PERFORMANCE CHARACTERISTICS 450 VS = ±2.5V 400 SUPPLY CURRENT (µA) SUPPLY VOLTAGE (V) 5 6 4 350 3 300 2 250 03024-002 1 03024-005 200 4.65 4.70 4.75 4.80 4.85 4.90 4.95 0 4.65 4.70 4.75 4.80 4.85 4.90 4.95 BANDWIDTH (MHz) BANDWIDTH (MHz) Figure 2. Supply Current vs. Bandwidth 450 400 160 Figure 5. Supply Voltage vs. Bandwidth VS = ±2.5V 140 VOL VOH 100 80 60 40 03024-006 300 250 200 150 100 03024-003 ΔOUTPUT VOLTAGE (mV) 350 SUPPLY CURRENT (µA) 120 50 0 0 1 2 3 4 5 6 20 0 0 5 10 LOAD CURRENT (mA) 15 20 SUPPLY VOLTAGE (V) Figure 3. Supply Current vs. Supply Voltage 500 VS = 5V 120 100 80 450 60 40 20 0 –20 350 –40 03024-004 Figure 6. Output Voltage to Supply Rail vs. Load Current 270 VS = ±2.5V AMPLITUDE = 20mV 225 180 GAIN GAIN (dB) ISY (µA) PHASE 90 45 0 –45 –90 –135 400 –60 –80 1k 10k 100k 1M 10M 300 –50 –25 0 25 50 75 100 125 150 –180 50M TEMPERATURE (°C) FREQUENCY (Hz) Figure 4. ISY vs. Temperature Figure 7. Gain and Phase vs. Frequency Rev. D | Page 7 of 16 03024-007 PHASE (DEGREES) 135 AD8515 120 100 80 60 PSRR (dB) ACL (dB) 96 VS = ±2.5V 92 VS = ±2.5V 40 20 0 –20 –40 G = 100 G = 10 G=1 88 84 80 03024-008 03024-011 –60 –80 10k 100k 1M FREQUENCY (Hz) 10M 30M 76 –50 0 50 TEMPERATURE (°C) 100 150 Figure 8. ACL vs. Frequency 120 100 80 60 CMRR (dB) NUMBER OF AMPLIFIERS Figure 11. PSRR vs. Temperature 430 VS = ±2.5V 344 VS = ±2.5V AMPLITUDE = 50mV 40 20 0 –20 –40 03024-009 258 172 86 03024-012 –60 –80 10k 100k 1M FREQUENCY (Hz) 10M 100M 0 –6.24 –4.27 –2.29 –0.32 1.66 3.63 VOS (mV) Figure 9. CMRR vs. Frequency 140 120 100 80 60 40 20 03024-010 Figure 12. VOS Distribution 150 VS = ±2.5V AMPLITUDE = 50mV VS = ±2.5V OUTPUT IMPEDANCE (Ω) +PSRR 100 PSRR (dB) –PSRR 50 –20 100 1k 10k 100k 1M 0 1k 10k 100k FREQUENCY (Hz) 1M 10M FREQUENCY (Hz) Figure 10. PSRR vs. Frequency Figure 13. Output Impedance vs. Frequency Rev. D | Page 8 of 16 03024-013 0 GAIN = 100 GAIN = 10 GAIN = 1 AD8515 25 24 23 –ISC VOLTAGE (2V/DIV) VS = 5V VS = ±2.5V VIN = 6.4V 22 ISC (mA) VIN VOUT 21 20 19 18 17 16 15 –50 0 50 TEMPERATURE (°C) 100 03024-014 +ISC 150 TIME (200µs/DIV) Figure 14. ISC vs. Temperature Figure 17. No Phase Reversal VS = ±2.5V VS = ±2.5V CL = 50pF VIN = 200mV VOLTAGE (100mV/DIV) VOLTAGE (13µV/DIV) 03024-015 0 250 500 750 1k 1.25k 1.5k 1.75k 2k 2.25k 2.5k TIME (1µs/DIV) FREQUENCY (Hz) Figure 15. Voltage Noise Density Figure 18. Small Signal Transient Response VS = ±2.5V GAIN = 100 VS = ±2.5V CL = 500pF VIN = 200mV VOLTAGE (100mV/DIV) VOLTAGE (200mV/DIV) 03024-016 TIME (1s/DIV) TIME (1µs/DIV) Figure 16. Input Voltage Noise Figure 19. Small Signal Transient Response Rev. D | Page 9 of 16 03024-019 03024-018 03024-017 AD8515 VS = ±2.5V CL = 300pF VIN = 4V 120 100 80 VOLTAGE (1V/DIV) VS = ±1.5V AMPLITUDE = 50mV 60 CMRR (dB) 03024-020 40 20 0 –20 –40 –60 –80 10k 100k 1M FREQUENCY (Hz) 10M 03024-023 100M TIME (1µs/DIV) Figure 20. Large Signal Transient Response Figure 23. CMRR vs. Frequency 100mV VIN VS = ±1.5V GAIN = –40 VIN = 100mV VS = ±0.9V CL = 50pF VIN = 200mV VOLTAGE 0V 0V 2V VOUT 03024-021 VOLTAGE (100mV/DIV) TIME (2µs/DIV) TIME (1µs/DIV) Figure 21. Saturation Recovery Figure 24. Small Signal Transient Response 0V VS = ±1.5V GAIN = –40 VIN = 100mV 120 VIN 270 VS = ±0.9V AMPLITUDE = 20mV 225 180 PHASE (DEGREES) 03024-025 100 80 60 135 90 45 0 –45 –90 –135 100k 1M FREQUENCY (Hz) 10M –180 30M VOLTAGE –100mV 2V VOUT 0V GAIN (dB) 40 20 0 –20 –40 03024-022 –60 –80 10k TIME (2µs/DIV) Figure 22. Saturation Recovery Figure 25. Gain and Phase vs. Frequency Rev. D | Page 10 of 16 03024-024 AD8515 200 VS = ±0.9V 4.994 OUTPUT IMPEDANCE (Ω) 4.995 VS = 5V IL = 750µA 150 4.993 100 50 03024-026 03024-029 GAIN = 100 GAIN = 10 100k GAIN = 1 0 1k 10k 1M 10M VOH (V) 4.992 4.991 4.990 –50 0 50 TEMPERATURE (°C) 100 150 FREQUENCY (Hz) Figure 26. Output Impedance vs. Frequency 80 Figure 29. VOH vs. Temperature VS = ±0.9V VIN = 3.2V VIN VOLTAGE (1V/DIV) VS = 5V 77 VOUT CMRR (dB) 03024-027 74 71 68 03024-030 65 –50 0 50 TEMPERATURE (°C) 100 150 TIME (200µs/DIV) Figure 27. No Phase Reversal 11 VS = 5V IL = 750µA 9 Figure 30. CMRR vs. Temperature VOL (mV) 7 5 03024-028 3 –50 0 50 TEMPERATURE (°C) 100 150 Figure 28. VOL vs. Temperature Rev. D | Page 11 of 16 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. 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 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 POWER CONSUMPTION vs. BANDWIDTH 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 AD8515 DRIVING CAPACITIVE LOADS 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. 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 VOLTAGE (100mV/DIV) VS = ±0.9V CL = 800pF GAIN = –1 VOLTAGE (100mV/DIV) TIME (1µs/DIV) Figure 33. Capacitive Load Driving @ CL = 800 pF FULL POWER BANDWIDTH 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 for a given distortion. The FPBW of the AD8515 is shown in Figure 34 to be close to 200 kHz. 03024-031 VIN VOLTAGE (2V/DIV) TIME (1µs/DIV) Figure 31. Capacitive Load Driving @ CL = 50 pF VS = ±2.5V CL = 500pF GAIN = 1 VOLTAGE (10mV/DIV) TIME (2µs/DIV) Figure 34. Full Power Bandwidth TIME (1µs/DIV) Figure 32. Capacitive Load Driving @ CL = 500 pF 03024-032 Rev. D | Page 13 of 16 03024-034 VOUT 03024-033 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 fL = fH = 1 2 π × R1 × C1 1 2 π × R1 × C1 R1 R2 H0 = 1 + 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 R2 1MΩ C3 1µF R1 1MΩ 3 4 + – U1 V+ V– 1 R4 100Ω 0.9V TO 2.5V C1 1µF R6 1MΩ V11 400mV 03024-035 AD8515 C2 0.022µF R3 10kΩ R5 2kΩ 3 + U9 V+ V– 0 R2 20kΩ C6 10pF 1 VOUT 4– C1 2nF R1 5kΩ AD8515 C3 1µF R8 1MΩ Figure 35. Micropower Voltage Reference Generator 0 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. 0 1k 10k 100k 1M 10M 100M FREQUENCY (Hz) Figure 37. Frequency Response of the Band-Pass Filter Rev. D | Page 14 of 16 03024-037 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. Figure 36. Second-Order Band-Pass Filter 2 OUTPUT VOLTAGE (V) 1.5 1 0.5 03024-036 A 100 kHz SINGLE-SUPPLY SECOND-ORDER BAND-PASS FILTER AD8515 WIEN BRIDGE OSCILLATOR 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 = 1 2 πR10 × C10 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). 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. C9 1nF R19 1kΩ VCC 3 2 + – U10 V+ V– VEE R12 1kΩ R11 2.05kΩ 03024-038 VOLTAGE (2V/DIV) Figure 39. Output of Wien Bridge Oscillator 1 C10 1nF R13 1kΩ AD8515 Figure 38. Low Power Wien Bridge Oscillator Rev. D | Page 15 of 16 03024-039 AD8515 OUTLINE DIMENSIONS 2.90 BSC 5 4 1.60 BSC 1 2 3 2.80 BSC PIN 1 0.95 BSC 1.30 1.15 0.90 1.90 BSC 1.45 MAX 0.22 0.08 10° 5° 0° 0.60 0.45 0.30 0.15 MAX 0.50 0.30 SEATING PLANE 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 PIN 1 1.00 0.90 0.70 5 1 2 4 3 2.40 2.10 1.80 0.65 BSC 1.10 0.80 0.40 0.10 0.46 0.36 0.26 0.10 MAX 0.30 0.15 SEATING PLANE 0.22 0.08 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 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# 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