AD AD8515AKS 1.8 v low power cmos rail-to-rail input/output operational amplifier Datasheet

a
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 Max
Space-Saving SOT-23 and SC70 Packages
Slew Rate: 2.7 V/␮s
Bandwidth: 5 MHz
Rail-to-Rail Input and Output Swing
Low Input Bias Current: 2 pA Typ
Low Supply Current @ 1.8 V: 450 ␮A Max
PIN CONFIGURATION
5-Lead SC70 and SOT-23
(KS and RT Suffixes)
5 V+
OUT 1
V–
2
+IN 3
AD8515
4 ⴚIN
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 SOT-23-5L and
SC70-5L 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/ms 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 (–40∞C to +125∞C).
REV. B
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. 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 companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
© 2003 Analog Devices, Inc. All rights reserved.
AD8515–SPECIFICATIONS
ELECTRICAL CHARACTERISTICS (V = 1.8 V, V
S
CM
= VS/2, TA = 25ⴗC, unless otherwise noted.)
Parameter
Symbol
Condition
INPUT CHARACTERISTICS
Offset Voltage
VOS
VCM = VS/2
–40∞C < TA < +125∞C
VS = 1.8 V
–40∞C < TA < +85∞C
–40∞C < TA < +125∞C
Input Bias Current
IB
Input Offset Current
IOS
Min
Typ
Max
Unit
1
6
8
30
600
8
10
300
1.8
400
4
mV
mV
pA
pA
nA
pA
pA
V
dB
V/mV
mV/∞C
20
V
V
mV
mV
mA
2
1
–40∞C < TA < +125∞C
Input Voltage Range
Common-Mode Rejection Ratio CMRR
Large Signal Voltage Gain
AVO
Offset Voltage Drift
DVOS/DT
OUTPUT CHARACTERISTICS
Output Voltage High
VOH
Output Voltage Low
VOL
Short Circuit Limit
ISC
0 V £ VCM £ 1.8 V
RL = 100 kW, 0.3 V £ VOUT £ 1.5 V
IL = 100 mA,
IL = 750 mA,
IL = 100 mA,
IL = 750 mA,
–40∞C < TA < +125∞C
–40∞C < TA < +125∞C
–40∞C < TA < +125∞C
–40∞C < TA < +125∞C
0
50
110
1.79
1.77
10
30
POWER SUPPLY
Supply Current/Amplifier
ISY
VOUT = VS/2
–40∞C < TA < +125∞C
300
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
SR
GBP
RL = 10 kW
2.7
5
V/ms
MHz
NOISE PERFORMANCE
Voltage Noise Density
en
Current Noise Density
in
f = 1 kHz
f = 10 kHz
f = 1 kHz
22
20
0.05
nV/÷Hz
nV/÷Hz
pA/÷Hz
450
500
mA
mA
Specifications subject to change without notice.
–2–
REV. B
AD8515
ELECTRICAL CHARACTERISTICS (V = 3.0 V, V
S
CM
= VS/2, TA = 25ⴗC, unless otherwise noted.)
Parameter
Symbol
Condition
INPUT CHARACTERISTICS
Offset Voltage
VOS
VCM =VS/2
–40∞C < TA < +125∞C
VS = 3.0 V
–40∞C < TA < +85∞C
–40∞C < TA < +125∞C
Input Bias Current
IB
Input Offset Current
IOS
Min
Typ
Max
Unit
1
6
8
30
600
8
10
300
3
mV
mV
pA
pA
nA
pA
pA
V
dB
V/mV
mV/∞C
2
1
–40∞C < TA < +125∞C
Input Voltage Range
Common-Mode Rejection Ratio CMRR
Large Signal Voltage Gain
AVO
Offset Voltage Drift
DVOS/DT
OUTPUT CHARACTERISTICS
Output Voltage High
VOH
Output Voltage Low
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
VOL
PSRR
ISY
0 V £ VCM £ 3.0 V
RL = 100 kW, 0.3 V £ VOUT £ 2.7 V
IL = 100 mA, –40∞C < TA < +125∞C
IL = 750 mA, –40∞C < TA < +125∞C
IL = 100 mA, –40∞C < TA < +125∞C
IL = 750 mA, –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
54
250
1,000
4
2.99
2.98
65
85
300
10
20
V
V
mV
mV
450
500
dB
mA
mA
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
SR
GBP
RL = 10 kW
2.7
5
V/ms
MHz
NOISE PERFORMANCE
Voltage Noise Density
en
Current Noise Density
in
f = 1 kHz
f = 10 kHz
f = 1 kHz
22
20
0.05
nV/÷Hz
nV/÷Hz
pA/÷Hz
Specifications subject to change without notice.
REV. B
–3–
AD8515
ELECTRICAL CHARACTERISTICS (V = 5.0 V, V
S
CM
= VS/2, TA = 25ⴗC, unless otherwise noted.)
Parameter
Symbol
Condition
INPUT CHARACTERISTICS
Offset Voltage
VOS
VCM =VS/2
–40∞C < TA < +125∞C
VS = 5.0 V
–40∞C < TA < +85∞C
–40∞C < TA < +125∞C
Input Bias Current
IB
Input Offset Current
IOS
Min
Typ
Max
Unit
1
6
8
30
600
8
10
300
5.0
mV
mV
pA
pA
nA
pA
pA
V
dB
V/mV
mV/∞C
5
1
–40∞C < TA < +125∞C
Input Voltage Range
Common-Mode Rejection Ratio CMRR
Large Signal Voltage Gain
AVO
Offset Voltage Drift
DVOS/DT
OUTPUT CHARACTERISTICS
Output Voltage High
VOH
Output Voltage Low
POWER SUPPLY
Power Supply Rejection Ratio
Supply Current/Amplifier
VOL
PSRR
ISY
0 V £ VCM £ 5.0 V
RL = 100 kW, 0.3 V £ VOUT £ 4.7 V
IL = 100 mA, –40∞C < TA < +125∞C
IL = 750 mA, –40∞C < TA < +125∞C
IL = 100 mA, –40∞C < TA < +125∞C
IL = 750 mA, –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
500
75
2,000
4
4.99
4.98
65
82
350
10
20
V
V
mV
mV
500
600
dB
mA
mA
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
SR
GBP
RL = 10 kW
2.7
5
V/ms
MHz
NOISE PERFORMANCE
Voltage Noise Density
en
Current Noise Density
in
f = 1 kHz
f = 10 kHz
f = 1 kHz
22
20
0.05
nV/÷Hz
nV/÷Hz
pA/÷Hz
Specifications subject to change without notice.
–4–
REV. B
AD8515
ABSOLUTE MAXIMUM RATINGS*
(TA = 25∞C, unless otherwise noted.)
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND to VS
Differential Input Voltage . . . . . . . . . . . . . . . . . . ± 6 V or ± VS
Output Short-Circuit Duration
to GND . . . . . . . . . . . . . . . . . . . . Observe Derating Curves
Storage Temperature Range
KS and RT Packages . . . . . . . . . . . . . . . . –65∞C to +150∞C
Operating Temperature Range
AD8515 . . . . . . . . . . . . . . . . . . . . . . . . . . –40∞C to +125∞C
Junction Temperature Range
KS and RT Packages . . . . . . . . . . . . . . . . –65∞C to +150∞C
Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300∞C
Package Type
␪JA*
␪JC
Unit
5-Lead SOT-23 (RT)
5-Lead SC70 (KS)
230
376
146
126
∞C/W
∞C/W
*qJA is specified for worst-case conditions, i.e., qJA is specified for device soldered in circuit board for surface-mount packages.
*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 listed in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
ORDERING GUIDE
Model
Temperature Range
Package Description
Package Option
AD8515ART
AD8515AKS
–40ºC to +125ºC
–40ºC to +125ºC
5-Lead SOT-23
5-Lead SC70
RT-5
KS-5
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although the
AD8515 features proprietary ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended
to avoid performance degradation or loss of functionality.
REV. B
–5–
AD8515–Typical Performance Characteristics
6
450
VS = 2.5V
5
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (␮A)
400
350
300
4
3
2
250
1
200
4.65
4.70
4.75
4.80
4.85
BANDWIDTH (MHz)
4.90
0
4.65
4.95
TPC 1. Supply Current vs. Bandwidth
4.70
4.75
4.80
4.85
BANDWIDTH
4.90
4.95
TPC 4. Supply Voltage vs. Bandwidth
450
160
400
140
VS = 2.5V
VOL
120
DOUTPUT VOLTAGE (mV)
300
VOH
100
250
200
150
100
80
60
40
20
50
0
1
0
2
3
4
SUPPLY VOLTAGE (V)
5
0
6
TPC 2. Supply Current vs. Supply Voltage
0
5
10
LOAD CURRENT (mA)
20
15
TPC 5. Output Voltage to Supply Rail vs. Load Current
500
270
120
VS = 5V
VS = 2.5V
AMPLITUDE = 20mV
100
225
180
80
450
GAIN
135
GAIN (dB)
ISY (␮A)
60
400
90
40
PHASE
45
20
0
0
PHASE – Degrees
SUPPLY CURRENT (␮A)
350
–20
–45
–40
–90
–60
–135
350
300
–50
–25
0
25
50
75
TEMPERATURE (ⴗC)
100
125
–80
150
TPC 3. ISY vs. Temperature
1k
10k
100k
1M
FREQUENCY (Hz)
10M
–180
50M
TPC 6. Gain and Phase vs. Frequency
–6–
REV. B
AD8515
96
120
VS = 2.5V
VS = 2.5V
100
92
80
G = 100
40
PSRR (dB)
ACL (dB)
60
G = 10
20
G=1
0
88
84
–20
80
–40
–60
–80
10k
100k
1M
FREQUENCY (Hz)
76
–50
30M
10M
0
TPC 7. ACL vs. Frequency
150
430
VS = 2.5V
AMPLITUDE = 50mV
VS = 2.5V
344
NUMBER OF AMPLIFIERS
80
60
40
CMRR (dB)
100
TPC 10. PSRR vs. Temperature
120
100
50
TEMPERATURE (ⴗC)
20
0
–20
258
172
86
–40
–60
–80
10k
100k
1M
FREQUENCY (Hz)
10M
0
–6.24
100M
TPC 8. CMRR vs. Frequency
–2.29
–0.32
VOS (mV)
–4.27
1.66
3.63
TPC 11. VOS Distribution
120
150
100
+PSRR
VS = 2.5V
VS = 2.5V
AMPLITUDE = 50mV
60
OUTPUT IMPEDANCE (⍀)
80
–PSRR
PSRR (dB)
40
20
10
0
100
50
GAIN = 100
–20
GAIN = 10
GAIN = 1
100k
FREQUENCY (Hz)
1M
–40
–60
100
1k
10k
100k
FREQUENCY (Hz)
1M
0
1k
10M
TPC 9. PSRR vs. Frequency
REV. B
10k
TPC 12. Output Impedance vs. Frequency
–7–
10M
AD8515
0
25
VS = 5V
24
VS = 2.5V
VIN = 6.4V
0
23
ISC (mA)
VOLTAGE (2V/DIV)
0
22
–ISC
21
+ISC
20
19
VIN
0
VOUT
0
0
18
0
17
0
16
15
–50
0
50
TEMPERATURE (ⴗC)
0
150
100
0
0
0
0
0
0
0
0
0
0
0
0
VS = 2.5V
VS = 2.5V
CL = 50pF
VIN = 200mV
0
0
0
VOLTAGE (100mV/DIV)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
FREQUENCY (Hz)
0
0
0
TIME (1␮s/DIV)
0
TPC 17. Small Signal Transient Response
TPC 14. Voltage Noise Density
0
0
VS = 2.5V
GAIN = 100k⍀
0
VS = 2.5V
CL = 500pF
VIN = 200mV
0
0
VOLTAGE (100mV/DIV)
0
VOLTAGE (200mV/DIV)
0
0
0
TIME (200␮s/DIV)
TPC 16. No Phase Reversal
TPC 13. ISC vs. Temperature
VOLTAGE (13␮V/DIV)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TIME (1s/DIV)
0
0
0
0
0
0
0
0
0
0
0
TIME (1␮s/DIV)
0
0
0
0
TPC 18. Small Signal Transient Response
TPC 15. Input Voltage Noise
–8–
REV. B
AD8515
120
0
VS = 2.5V
CL = 300pF
VIN = 4V
0
VS = 1.5V
AMPLITUDE = 50mV
100
80
0
VOLTAGE (1V/DIV)
60
40
CMRR (dB)
0
0
20
0
0
–20
0
–40
0
–60
–80
10k
0
0
0
0
0
0
0
0
TIME (1␮s/DIV)
0
0
0
0
100k
100M
10M
TPC 22. CMRR vs. Frequency
TPC 19. Large Signal Transient Response
0
0
VS = 1.5V
GAIN = –40
VIN = 100mV
VIN
0
100mV
VS = 0.9V
CL = 50pF
VIN = 200mV
0
0
VOLTAGE (100mV/DIV)
0
0V
0
VOLTAGE
1M
FREQUENCY (Hz)
0
0V
0
2V
0
VOUT
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
TIME (2␮s/DIV)
0
0
0
0
0
0
0
0
0
0
0
TIME (1␮s/DIV)
0
0
0
0
TPC 23. Small Signal Transient Response
TPC 20. Saturation Recovery
120
0
VS = 1.5V
GAIN = –40
VIN = 100mV
0V
0
100
VIN
270
VS = 0.9V
AMPLITUDE = 20mV
225
80
180
60
135
40
90
20
45
0
2V
GAIN (dB)
VOLTAGE
–100mV
0
VOUT
0
0V
0
0
0
0
0
0
0
0
0
0
TIME (2␮s/DIV)
0
0
0
0
0
–20
–45
–40
–90
–60
–135
–80
10k
100k
1M
FREQUENCY (Hz)
10M
–180
30M
TPC 24. Gain and Phase vs. Frequency
TPC 21. Saturation Recovery
REV. B
0
–9–
PHASE (Degrees)
0
AD8515
4.995
200
VS = 5V
IL = 750␮A
VS = 0.9V
4.993
VOH (V)
OUTPUT IMPEDANCE (⍀)
4.994
150
100
4.992
GAIN = 100
50
4.991
GAIN = 10
0
1k
10k
GAIN = 1
100k
FREQUENCY (Hz)
4.990
–50
10M
1M
TPC 25. Output Impedance vs. Frequency
0
50
TEMPERATURE (ⴗC)
150
100
TPC 28. VOH vs. Temperature
0
80
VS = 0.9V
VIN = 3.2V
0
VS = 5V
77
VIN
0
CMRR (dB)
VOLTAGE (1V/DIV)
0
VOUT
0
0
74
71
0
68
0
0
0
0
0
0
0
0
0
TIME (200␮s/DIV)
0
0
0
65
–50
0
TPC 26. No Phase Reversal
0
50
TEMPERATURE ( ⴗC)
100
150
TPC 29. CMRR vs. Temperature
11
VS = 5V
IL = 750␮A
VOL (mV)
9
7
5
3
–50
0
50
TEMPERATURE (ⴗC)
100
150
TPC 27. VOL vs. Temperature
–10–
REV. B
AD8515
0
FUNCTIONAL DESCRIPTION
The input stage consists of two parallel, complementary, differential
pairs of PMOS and NMOS. The AD8515 exhibits no phase reversal as 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 4,000 V.
VS = 2.5V
CL = 50pF
GAIN = +1
0
0
VOLTAGE (100mV/DIV)
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 (i.e., bandwidth) in the industry. With a
small amount of supply current (less than 400 mA), a wide unity
gain bandwidth of 4.5 MHz is available for signal processing.
0
0
0
0
0
0
0
0
0
0
0
0
0
TIME (1␮s/DIV)
0
0
0
0
Power Consumption vs. Bandwidth
The AD8515 is ideal for battery-powered instrumentation and
handheld devices since it can operate at the end of discharge
voltage of most popular batteries. Table I lists the nominal and
end of discharge voltages of several typical batteries.
Figure 1a. Capacitive Load Driving @ CL = 50 pF
0
VS = 2.5V
CL = 500pF
GAIN = +1
0
0
VOLTAGE (100mV/DIV)
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 TPC 1 through
TPC 3. This product solves the speed/power requirements for
many applications. The wide bandwidth is also stable even when
operated with low supply voltages. TPC 4 shows the relationship
between the supply voltage versus the bandwidth for the AD8515.
0
0
0
0
Table I. Typical Battery Life Voltage Range
Nominal Voltage (V)
Lead-Acid
Lithium
NiMH
NiCd
Carbon-Zinc
2
2.6–3.6
1.2
1.2
1.5
1.8
1.7–2.4
1
1
1.1
0
0
0
0
0
0
0
0
TIME (1␮s/DIV)
0
0
0
0
0
VS = 0.9V
CL = 800pF
GAIN = –1
0
DRIVING CAPACITIVE LOADS
0
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 could 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 Figures 1a and 1b 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 2.
REV. B
0
Figure 1b. Capacitive Load Driving @ CL = 500 pF
–11–
VOLTAGE (100mV/DIV)
Battery
End of Discharge
Voltage (V)
0
0
0
0
0
0
0
0
0
0
0
0
0
TIME (1␮s/DIV)
0
0
0
0
Figure 2. Capacitive Load Driving @ CL = 800 pF
AD8515
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
2p ¥ VPEAK
for a given distortion. The FPBW of AD8515 is shown in Figure 3
to be close to 200 kHz.
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 mF capacitor.
0
0
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 6 shows. When the op amp’s bandwidth
is close to the filter’s center frequency, the amplifier’s internal
phase shift causes excess phase shift at 100 kHz, which alters
the filter’s response. In fact, if the chosen op amp has a bandwidth
close to 100 kHz, the phase shift of the op amps will cause the
loop to oscillate.
VIN
1
2p ¥ R1 ¥ C1
1
fH =
2p ¥ R1 ¥ C1
R2
H0 = 1 +
R1
VCC = 1.8 V - 5 V
fL =
VOLTAGE (2V/DIV)
0
0
0
0
0
VOUT
0
where:
fL is the low –3 db frequency.
0
0
0
0
0
0
0
0
TIME (2␮s/DIV)
0
0
0
0
fH is the high –3 db frequency.
H0 is the midfrequency gain.
Figure 3. Full Power Bandwidth
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 4 shows the schematic for such a circuit. The
two 1 MW resistors generate the reference voltages while drawing
only 0.9 mA 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.
VCC
VCC
R5
2k⍀
R6
1M⍀
3
400mV
C3
1␮F
4
C1
2nF
R8
1M⍀
U9
1
V+
V11
R1
5k⍀
VOUT
V–
AD8515
0
R2
20k⍀
0
C6
10pF
1.8V TO 5V
C3
1␮F
R1
1M⍀
Figure 5. Second Order Band-Pass Filter
3
U1
V+
2
1
R4
100⍀
2
0.9V TO 2.5V
V–
AD8515
C1
1␮F
OUTPUT VOLTAGE ( V)
R2
1M⍀
C2
0.022␮F
R3
10k⍀
Figure 4. Micropower Voltage Reference Generator
1
A 100 kHz Single-Supply Second Order Band-Pass Filter
The circuit in Figure 5 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 has a loop gain at 100 kHz in order to maintain an accurate
center frequency. This loop gain requirement necessitates the
–12–
0
1k
10k
100k
1M
FREQUENCY (Hz)
10M
100M
Figure 6. Frequency Response of the Band-Pass Filter
REV. B
AD8515
The circuit in Figure 7 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 will happen 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 8. If R11 is too low, the
oscillation might converge; if too large, the oscillation will diverge
until the output clips (VS = ± 2.5 V, FOSC = 130 kHz).
1
=
2pR10 ¥ C10
Second, at this frequency, the ratio of VOUT to the voltage at
+input (Pin 3) has to be 3, which means that the ratio of
R11/R12 should be greater than 2.
0
0
0
VOLTAGE (2V/DIV)
Wien Bridge Oscillator
0
0
0
0
0
C9
1nF
R10
1k⍀
0
0
VCC
0
0
0
0
0
0
TIME (2␮s/DIV)
0
0
0
Figure 8. Output of Wien Bridge Oscillator
3
U10
1
V+
C10
1nF
R13
1k⍀
2
V–
AD8515
VEE
R12
1k⍀
R11
2.05k⍀
Figure 7. Low Power Wien Bridge Oscillator
REV. B
–13–
0
AD8515
OUTLINE DIMENSIONS
5-Lead Small Outline Transistor Package [SOT-23]
(RT-5)
Dimensions shown in millimeters
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
0.35
0.22
0.08
10ⴗ
5ⴗ
0ⴗ
SEATING
PLANE
0.55
0.45
0.35
COMPLIANT TO JEDEC STANDARDS MO-178AA
5-Lead Thin Shrink Small Outline Transistor Package [SC70]
(KS-5)
Dimensions shown in millimeters
2.00 BSC
4
5
1.25 BSC
2.10 BSC
1
2
3
PIN 1
0.65 BSC
1.00
0.90
0.70
0.10 MAX
1.10 MAX
0.22
0.08
0.30
0.15
0.10 COPLANARITY
SEATING
PLANE
0.46
0.36
0.26
COMPLIANT TO JEDEC STANDARDS MO-203AA
–14–
REV. B
AD8515
Revision History
Location
Page
4/03—Data Sheet changed from REV. A to REV. B.
Change to Figure 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2/03—Data Sheet changed from 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
REV. B
–15–
–16–
C03024–0–4/03(B)