AD AD8515ARTZ-R2 1.8 v low power cmos rail-to-rail input/output operational amplifier Datasheet

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
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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#