1.8 V Low Power CMOS Rail-to-Rail
a
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
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/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 (–40°C to +125°C).
Input/Output Operational Amplifier
AD8515
PIN CONFIGURATION
5-Lead SC70 and SOT-23
(KS and RT Suffixes)
OUT
+IN
1
V–
2
AD8515
3
V+
5
ⴚIN
4
REV. C
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 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 © 2005 Analog Devices, Inc. All rights reserved.
AD8515–SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
(VS = 1.8 V, VCM = VS/2, TA = 25ⴗC, unless otherwise noted.)
Parameter Symbol Condition Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage V
Input Bias Current I
Input Offset Current I
OS
B
OS
VCM = VS/2 16mV
–40°C < T
< +125°C8mV
A
VS = 1.8 V 2 30 pA
–40°C < T
–40°C < T
< +85°C 600 pA
A
< +125°C8nA
A
110pA
–40°C < T
< +125°C 500 pA
A
Input Voltage Range 0 1.8 V
Common-Mode Rejection Ratio CMRR 0 V ≤ V
–40°C < T
Large Signal Voltage Gain A
VO
RL = 100 kΩ, 0.3 V ≤ V
≤ 1.8 V 50 dB
CM
< +125°C47 dB
A
≤ 1.5 V 110 400 V/mV
OUT
Offset Voltage Drift ∆VOS/∆T4µV/°C
OUTPUT CHARACTERISTICS
Output Voltage High V
Output Voltage Low V
Short Circuit Limit I
OH
OL
SC
IL = 100 µA, –40°C < TA < +125°C 1.79 V
= 750 µA, –40°C < TA < +125°C 1.77 V
I
L
IL = 100 µA, –40°C < TA < +125°C10mV
I
= 750 µA, –40°C < TA < +125°C30mV
L
20 mA
POWER SUPPLY
Supply Current/Amplifier I
SY
V
= VS/2 300 450 µA
OUT
–40°C < TA < +125°C 500 µA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 10 kΩ 2.7 V/µs
Gain Bandwidth Product GBP 5 MHz
NOISE PERFORMANCE
Voltage Noise Density e
n
f = 1 kHz 22 nV/√Hz
f = 10 kHz 20 nV/√Hz
Current Noise Density i
Specifications subject to change without notice.
n
f = 1 kHz 0.05 pA/√Hz
REV. C–2–
AD8515
ELECTRICAL CHARACTERISTICS
(VS = 3.0 V, VCM = VS/2, TA = 25ⴗC, unless otherwise noted.)
Parameter Symbol Condition Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage V
Input Bias Current I
Input Offset Current I
OS
B
OS
VCM =VS/2 16mV
–40°C < T
< +125°C8mV
A
VS = 3.0 V 2 30 pA
–40°C < T
–40°C < T
< +85°C 600 pA
A
< +125°C8nA
A
110pA
–40°C < T
< +125°C 500 pA
A
Input Voltage Range 0 3 V
Common-Mode Rejection Ratio CMRR 0 V ≤ V
–40°C < T
Large Signal Voltage Gain A
VO
RL = 100 kΩ, 0.3 V ≤ V
≤ 3.0 V 54 dB
CM
< +125°C50 dB
A
≤ 2.7 V 250 1,000 V/mV
OUT
Offset Voltage Drift ∆VOS/∆T4µV/°C
OUTPUT CHARACTERISTICS
Output Voltage High V
Output Voltage Low V
OH
OL
IL = 100 µA, –40°C < TA < +125°C 2.99 V
= 750 µA, –40°C < TA < +125°C 2.98 V
I
L
IL = 100 µA, –40°C < TA < +125°C10mV
IL = 750 µA, –40°C < TA < +125°C20mV
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 1.8 V to 5.0 V 65 85 dB
< +125°C5780dB
A
= VS/2 300 450 µA
Supply Current/Amplifier I
SY
–40°C < T
V
OUT
–40°C < TA < +125°C 500 µA
DYNAMIC PERFORMANCE
Slew Rate SR R
= 10 kΩ 2.7 V/µs
L
Gain Bandwidth Product GBP 5 MHz
NOISE PERFORMANCE
Voltage Noise Density e
n
f = 1 kHz 22 nV/√Hz
f = 10 kHz 20 nV/√Hz
Current Noise Density i
Specifications subject to change without notice.
n
f = 1 kHz 0.05 pA/√Hz
REV. C
–3–
AD8515
ELECTRICAL CHARACTERISTICS
(VS = 5.0 V, VCM = VS/2, TA = 25ⴗC, unless otherwise noted.)
Parameter Symbol Condition Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage V
Input Bias Current I
Input Offset Current I
OS
B
OS
VCM =VS/2 16mV
–40°C < T
< +125°C8mV
A
VS = 5.0 V 5 30 pA
–40°C < T
–40°C < T
< +85°C 600 pA
A
< +125°C8nA
A
110pA
–40°C < T
< +125°C 500 pA
A
Input Voltage Range 0 5.0 V
Common-Mode Rejection Ratio CMRR 0 V ≤ V
–40°C < T
Large Signal Voltage Gain A
VO
RL = 100 kΩ, 0.3 V ≤ V
≤ 5.0 V 60 75 dB
CM
< +125°C54 dB
A
≤ 4.7 V 500 2,000 V/mV
OUT
Offset Voltage Drift ∆VOS/∆T4µV/°C
OUTPUT CHARACTERISTICS
Output Voltage High V
Output Voltage Low V
OH
OL
IL = 100 µA, –40°C < TA < +125°C 4.99 V
= 750 µA, –40°C < TA < +125°C 4.98 V
I
L
IL = 100 µA, –40°C < TA < +125°C10mV
IL = 750 µA, –40°C < TA < +125°C20mV
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = 1.8 V to 5.0 V 65 82 dB
< +125°C5780dB
A
= VS/2 350 500 µA
Supply Current/Amplifier I
SY
–40°C < T
V
OUT
–40°C < TA < +125°C 600 µA
DYNAMIC PERFORMANCE
Slew Rate SR R
= 10 kΩ 2.7 V/µs
L
Gain Bandwidth Product GBP 5 MHz
NOISE PERFORMANCE
Voltage Noise Density e
n
f = 1 kHz 22 nV/√Hz
f = 10 kHz 20 nV/√Hz
Current Noise Density i
Specifications subject to change without notice.
n
f = 1 kHz 0.05 pA/√Hz
REV. C–4–
AD8515
ABSOLUTE MAXIMUM RATINGS*
(TA = 25°C, unless otherwise noted.)
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND to V
Differential Input Voltage . . . . . . . . . . . . . . . . . . ±6 V or ±V
Output Short-Circuit Duration
to GND . . . . . . . . . . . . . . . . . . . . Observe Derating Curves
Package Type JA*
5-Lead SOT-23 (RT) 230 146 °C/W
S
5-Lead SC70 (KS) 376 126 °C/W
S
*θJA is specified for worst-case conditions, i.e., θ
dered in circuit board for surface-mount packages.
JA
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
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent 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 Branding
AD8515ART-R2 –40ºC to +125ºC 5-Lead SOT-23 RT-5 BDA
AD8515ART-REEL –40ºC to +125ºC 5-Lead SOT-23 RT-5 BDA
AD8515ART-REEL7 –40ºC to +125ºC 5-Lead SOT-23 RT-5 BDA
AD8515ARTZ-R2* –40ºC to +125ºC 5-Lead SOT-23 RT-5 AOH
AD8515ARTZ-REEL* –40ºC to +125ºC 5-Lead SOT-23 RT-5 AOH
AD8515ARTZ-REEL7* –40ºC to +125ºC 5-Lead SOT-23 RT-5 AOH
AD8515AKS-R2 –40ºC to +125ºC 5-Lead SC70 KS-5 BDA
AD8515AKS-REEL –40ºC to +125ºC 5-Lead SC70 KS-5 BDA
AD8515AKS-REEL7 –40ºC to +125ºC 5-Lead SC70 KS-5 BDA
AD8515AKSZ-R2* –40ºC to +125ºC 5-Lead SC70 KS-5 AOH
AD8515AKSZ-REEL* –40ºC to +125ºC 5-Lead SC70 KS-5 AOH
AD8515AKSZ-REEL7* –40ºC to +125ºC 5-Lead SC70 KS-5 AOH
*Z = Pb-free part.
JC
is specified for device sol-
Unit
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. C
–5–
AD8515–Typical Performance Characteristics
450
VS = 2.5V
400
350
300
SUPPLY CURRENT (A)
250
200
4.65 4.954.70
4.75 4.80 4.85 4.90
BANDWIDTH (MHz)
TPC 1. Supply Current vs. Bandwidth
450
400
350
300
250
200
150
SUPPLY CURRENT (A)
100
50
0
0
SUPPLY VOLTAGE (V)
6
5
4
3
2
SUPPLY VOLTAGE (V)
1
0
4.70 4.75 4.85
4.65
4.80
BANDWIDTH
4.90
4.95
TPC 4. Supply Voltage vs. Bandwidth
160
VS = 2.5V
140
120
100
80
60
∆OUTPUT VOLTAGE (mV)
40
20
0
612345
0205
LOAD CURRENT (mA)
V
OL
V
OH
10 15
TPC 2. Supply Current vs. Supply Voltage
500
VS = 5V
450
400
(A)
SY
I
350
300
–25 0 100
–50 150
25 50 75 125
TEMPERATURE (ⴗC)
TPC 3. ISY vs. Temperature
TPC 5. Output Voltage to Supply Rail vs. Load Current
120
VS = 2.5V
100
AMPLITUDE = 20mV
80
60
40
20
GAIN (dB)
0
–20
–40
–60
–80
1k 50M10k 1M 10M100k
GAIN
PHASE
FREQUENCY (Hz)
270
225
180
135
90
45
0
PHASE (Degrees)
–45
–90
–135
–180
TPC 6. Gain and Phase vs. Frequency
REV. C–6–
120
TEMPERATURE (ⴗC)
96
76
–50 150
PSRR (dB)
50
84
80
0 100
92
88
VS = 2.5V
VS = 2.5V
100
80
60
40
G = 10
(dB)
20
CL
G = 1
A
0
–20
–40
–60
–80
10k 30M100k
G = 100
FREQUENCY (Hz)
AD8515
1M 10M
120
100
80
60
40
20
0
CMRR (dB)
–20
–40
–60
–80
10k 100M100k
120
100
80
60
40
20
PSRR (dB)
10
0
–20
–40
–60
100 10M1k
TPC 7. ACL vs. Frequency
VS = 2.5V
AMPLITUDE = 50mV
1M 10M
FREQUENCY (Hz)
TPC 8. CMRR vs. Frequency
+PSRR
–PSRR
10k 100k 1M
FREQUENCY (Hz)
TPC 9. PSRR vs. Frequency
VS = 2.5V
AMPLITUDE = 50mV
TPC 10. PSRR vs. Temperature
430
VS = 2.5V
344
258
172
NUMBER OF AMPLIFIERS
86
0
–6.24 –4.27
–2.29 –0.32 1.66 3.63
VOS (mV)
TPC 11. VOS Distribution
150
VS = 2.5V
100
50
OUTPUT IMPEDANCE (⍀)
0
1k 10M
GAIN = 100
GAIN = 10 GAIN = 1
10k 100k 1M
FREQUENCY (Hz)
TPC 12. Output Impedance vs. Frequency
REV. C
–7–
AD8515
25
24
23
22
21
20
(mA)
SC
I
19
18
17
16
15
–50 150
+I
SC
TPC 13. I
0
VS = 2.5V
0
0
0
0
0
VOLTA GE (1 3V/DIV)
0
0
0
–I
SC
050
TEMPERATURE (ⴗC)
vs. Temperature
SC
FREQUENCY (Hz)
VS = 5V
100
TPC 14. Voltage Noise Density
0
VS = 2.5V
= 6.4V
V
IN
0
0
0
0
0
VOLTA GE (2V/DIV)
0
0
0
000
V
IN
V
OUT
00000000
TIME (200s/DIV)
TPC 16. No Phase Reversal
0
VS = 2.5V
= 50pF
C
L
0
V
= 200mV
IN
0
0
0
0
VOLTA GE (100mV/DIV)
0
0
0
000
00000000
TIME (1s/DIV)
TPC 17. Small Signal Transient Response
0
VS = 2.5V
GAIN = 100k⍀
0
0
0
0
0
VOLTA GE (200mV/DIV)
0
0
0
000
TPC 15. Input Voltage Noise
00000000
TIME (1s/DIV)
–8–
0
VS = 2.5V
= 500pF
C
L
0
V
= 200mV
IN
0
0
0
0
VOLTA GE (100mV/DIV)
0
0
0
000
00000000
TIME (1s/DIV)
TPC 18. Small Signal Transient Response
REV. C
AD8515
0
VS = 2.5V
= 300pF
C
L
0
= 4V
V
IN
0
0
0
0
VOLTA GE (1V/DIV)
0
0
0
000
00000000
TIME (1s/DIV)
TPC 19. Large Signal Transient Response
100mV
VOLTA G E
0
0
0
0V
0
0
0V
0
2V
0
0
0
000
V
IN
V
OUT
00000000
TIME (2s/DIV)
VS = 1.5V
GAIN = –40
V
TPC 20. Saturation Recovery
= 100mV
IN
CMRR (dB)
120
VS = 1.5V
100
AMPLITUDE = 50mV
80
60
40
20
0
–20
–40
–60
–80
10k 100M100k
1M 10M
FREQUENCY (Hz)
TPC 22. CMRR vs. Frequency
0
VS = 0.9V
= 50pF
C
L
0
= 200mV
V
IN
0
0
0
0
VOLTA GE (100mV/DIV)
0
0
0
000
00000000
TIME (1s/DIV)
TPC 23. Small Signal Transient Response
REV. C
–100mV
VOLTA G E
0
VS = 1.5V
GAIN = –40
0V
0
= 100mV
V
0
0
0
2V
0
0V
0
0
0
IN
000
V
IN
V
OUT
00000000
TIME (2s/DIV)
TPC 21. Saturation Recovery
–9–
120
= 0.9V
V
S
100
AMPLITUDE = 20mV
80
60
40
20
GAIN (dB)
0
–20
–40
–60
–80
10k 30M100k
FREQUENCY (Hz)
1M 10M
TPC 24. Gain and Phase vs. Frequency
270
225
180
135
90
45
0
PHASE (Degrees)
–45
–90
–135
–180
AD8515
200
VS = 0.9V
150
(⍀)
100
OUTPUT IMPEDANCE
50
0
1k 10M
GAIN = 100
GAIN = 10
10k 100k 1M
FREQUENCY (Hz)
GAIN = 1
TPC 25. Output Impedance vs. Frequency
0
VS = 0.9V
= 3.2V
V
IN
0
0
0
0
0
VOLTA GE (1V/DIV)
0
0
V
IN
V
OUT
4.995
4.994
4.993
(V)
OH
V
4.992
4.991
4.990
–50 150
0 100
50
TEMPERATURE (ⴗC)
TPC 28. VOH vs. Temperature
80
77
74
CMRR (dB)
71
68
VS = 5V
= 750A
I
L
VS = 5V
0
000
00000000
TIME (200s/DIV)
TPC 26. No Phase Reversal
11
VS = 5V
= 750A
I
L
9
(mV)
7
OL
V
5
3
–50 150
0 100
50
TEMPERATURE (ⴗC)
TPC 27. VOL vs. Temperature
65
–50 150
500 100
TEMPERATURE (
ⴗC)
TPC 29. CMRR vs. Temperature
–10–
REV. C
AD8515
FUNCTIONAL DESCRIPTION
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
small amount
to speed ratios (i.e., bandwidth) in the industry. With a
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 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.
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 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.
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.
Table I. Typical Battery Life Voltage Range
End of Discharge
Battery Nominal Voltage (V) Voltage (V)
Lead-Acid 2 1.8
Lithium 2.6–3.6 1.7–2.4
NiMH 1.2 1
NiCd 1.2 1
Carbon-Zinc 1.5 1.1
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 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.
0
VS = 2.5V
= 50pF
C
L
0
GAIN = +1
0
0
0
0
VOLTA GE (100mV/DIV)
0
0
0
000
00000000
TIME (1s/DIV)
Figure 1a. Capacitive Load Driving @ CL = 50 pF
0
VS = 2.5V
= 500pF
C
L
0
GAIN = +1
0
0
0
0
VOLTA GE (100mV/DIV)
0
0
0
000
00000000
TIME (1s/DIV)
Figure 1b. Capacitive Load Driving @ CL = 500 pF
0
VS = 0.9V
= 800pF
C
L
0
GAIN = –1
0
0
0
0
VOLTA GE (100mV/DIV)
0
0
0
000
00000000
TIME (1s/DIV)
Figure 2. Capacitive Load Driving @ CL = 800 pF
REV. C
–11–
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
=
V
×2π
PEAK
for a given distortion. The FPBW of AD8515 is shown in Figure 3
to be close to 200 kHz.
0
0
V
IN
0
0
0
0
VOLTA GE (2V/DIV)
0
V
OUT
0
0
000
00000000
TIME (2s/DIV)
Figure 3. Full Power Bandwidth
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.
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.
f
L
f
H
H
0
VCC
=
=
1
R1 C1
××
2
π
1
R1 C1
××
2
π
R2
=+
1
R1
=−
1.8 V 5 V
where:
f
is the low –3 dB frequency.
L
f
is the high –3 dB frequency.
H
H
is the midfrequency gain.
0
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 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
R2
1F
1M⍀
C3
R1
1M⍀
3
U1
1
V+
V–
2
AD8515
C2
0.022F
R3
10k⍀
R4
100⍀
0.9V TO 2.5V
C1
1F
Figure 4. Micropower Voltage Reference Generator
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
VCC
3
U9
1
V+
V–
4
AD8515
0
R2
20k⍀
C6
10pF
VOUT
1F
VCC
V11
C1
2nF
R5
2k⍀
R1
5k⍀
R6
1M⍀
400mV
1M⍀
R8
0
C3
Figure 5. Second Order Band-Pass Filter
2
1
OUTPUT VOLTAGE ( V)
0
1k 100M10k
100k 1M 10M
FREQUENCY (Hz)
Figure 6. Frequency Response of the Band-Pass Filter
–12–
REV. C
AD8515
Wien Bridge Oscillator
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
F
=
OSC
R10 C10
2π
1
×
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.
C9
R10
1nF
1k⍀
VCC
3
U10
1
V+
V–
R12
1k⍀
2
VEE
R11
2.05k⍀
AD8515
C10
1nF
R13
1k⍀
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 (V
0
0
0
0
0
0
VOLTA GE (2V/DIV)
0
0
0
000
00000000
= ±2.5 V, F
S
TIME (2s/DIV)
= 130 kHz).
OSC
Figure 8. Output of Wien Bridge Oscillator
Figure 7. Low Power Wien Bridge Oscillator
REV. C
–13–
AD8515
OUTLINE DIMENSIONS
5-Lead Small Outline Transistor Package [SOT-23]
(RT-5)
Dimensions shown in millimeters
2.90 BSC
4 5
0.50
0.35
2.80 BSC
0.95 BSC
1.45 MAX
SEATING
PLANE
0.22
0.08
10ⴗ
5ⴗ
0ⴗ
1.60 BSC
1.30
1.15
0.90
0.15 MAX
1 3
2
PIN 1
1.90
BSC
COMPLIANT TO JEDEC STANDARDS MO-178AA
0.55
0.45
0.35
5-Lead Thin Shrink Small Outline Transistor Package [SC70]
(KS-5)
Dimensions shown in millimeters
2.00 BSC
0.30
0.15
4
3
0.65 BSC
2.10 BSC
1.10 MAX
SEATING
PLANE
0.22
0.08
0.46
0.36
0.26
2
1.25 BSC
1.00
0.90
0.70
0.10 MAX
5
1
PIN 1
0.10 COPLANARITY
COMPLIANT TO JEDEC STANDARDS MO-203AA
–14–
REV. C
AD8515
Revision History
Location Page
3/05—Data Sheet changed from REV. B to REV. C.
Changes to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Changes to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
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. C
–15–
C03024–0–3/05(C)
–16–
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