A
DVANCED
L
INEAR
D
EVICES,
I
NC.
ALD2704A/ALD2704B
ALD2704
DUAL RAIL-TO-RAIL CMOS OPERATIONAL AMPLIFIER
GENERAL DESCRIPTION
The ALD2704 is a dual monolithic operational amplifier with MOSFET
input that has rail-to-rail input and output voltage ranges. The input
voltage range and output voltage range are very close to the positive and
negative power supply voltages. Typically the input voltage can be
beyond positive power supply voltage V + or the negative power supply
voltage V- by up to 300mV. The output voltage swings to within 60mV of
either positive or negative power supply voltages at rated load.
With high impedance load, the output voltage of the ALD2704 ap-
proaches within 1mV of the power supply rails. This device is designed
as an alternative to the popular J-FET input operational amplifier in
applications where lower operating voltages, such as 9V battery or
±3.25V
to
±6V
power supplies are being used. The ALD2704 offers high slew rate
of 5V/µs. It is designed and manufactured with Advanced Linear Devices'
standard enhanced ACMOS silicon gate CMOS process, and it offers low
unit cost and exceptional reliability.
The rail-to-rail input and output feature of the ALD2704 expands signal
voltage range for a given operating supply voltage and allows numerous
analog serial stages to be implemented without losing operating voltage
margin. The output stage is designed to drive up to 10mA into 400pF
capacitive and 1.5KΩ resistive loads at unity gain and up to 4000pF at a
gain of 5. Short circuit protection to either ground or the power supply rails
is at approximately 15mA clamp current. Due to complementary output
stage design, the output can source and sink 10mA into a load with
symmetrical drive and is ideally suited for applications where push-pull
voltage drive is desired.
For each of the operational amplifier, the offset voltage is trimmed on-chip
to eliminate the need for external nulling in many applications. For
precision applications, the output is designed to settle to 0.1% in 2µs. In
large signal buffer applications, the operational amplifier can function as
an ultrahigh input impedance voltage follower /buffer that allows input and
output voltage swings from positive to negative supply voltages. This
feature is intended to greatly simplify systems design and eliminate higher
voltage power supplies in many applications.
FEATURES
•
•
•
•
•
•
•
•
•
•
•
Rail-to-rail input and output voltage ranges
Symmetrical push-pull output drives
Output settles to 2mV of supply rails
5.0V/µs slew rate
High capacitive load capability -- up to 4000pF
No frequency compensation required -- unity
gain stable
Extremely low input bias currents -- <1.0pA
typical (20pA max.)
Ideal for high source impedance applications
High voltage gain -- typically 100V/mV
Output short circuit protected
Unity gain bandwidth of 2.1MHz
APPLICATIONS
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Voltage amplifier
Voltage follower/buffer
Charge integrator
Photodiode amplifier
Data acquisition systems
High performance portable instruments
Signal conditioning circuits
Low leakage amplifiers
Active filters
Sample/Hold amplifier
Picoammeter
Current to voltage converter
Coaxial cable driver
Capacitive sensor amplifier
Piezoelectric transducer amplifier
PIN CONFIGURATION
ORDERING INFORMATION
Operating Temperature Range*
-55°C to +125°C
0°C to +70°C
0°C to +70°C
8-Pin
CERDIP
Package
ALD2704A DA
ALD2704B DA
ALD2704 DA
8-Pin
Small Outline
Package (SOIC)
ALD2704A SA
ALD2704B SA
ALD2704 SA
8-Pin
Plastic Dip
Package
ALD2704A PA
ALD2704B PA
ALD2704 PA
OUT
A
-IN
A
+IN
A
V-
1
2
3
4
TOP VIEW
DA, PA, SA PACKAGE
8
7
6
5
V+
OUT
B
-IN
B
+IN
B
* Contact factory for industrial temperature range
© 1998 Advanced Linear Devices, Inc. 415 Tasman Drive, Sunnyvale, California 94089 -1706 Tel: (408) 747-1155 Fax: (408) 747-1286 http://www.aldinc.com
ABSOLUTE MAXIMUM RATINGS
Supply voltage, V
+
referenced to V
-
Supply voltage, V
S
referenced to V
-
Differential input voltage range
Power dissipation
Operating temperature range PA, SA package
DA package
Storage temperature range
Lead temperature, 10 seconds
-0.3V to V++13.2V
±6.6V
-0.3V to V + +0.3V
600 mW
0°C to +70°C
-55°C to +125°C
-65°C to +150°C
+260°C
OPERATING ELECTRICAL CHARACTERISTICS
T
A
= 25
°
C V
S
=
±
5.0V unless otherwise specified
Parameter
Supply
Voltage
Input Offset
Voltage
Input Offset
Current
Input Bias
Current
Input Voltage
Range
Input
Resistance
Input Offset
Voltage Drift
Power Supply
Rejection Ratio
Common Mode
Rejection Ratio
Large Signal
Voltage Gain
Output
Voltage
Range
Symbol
V
S
V
+
V
OS
I
OS
I
B
V
IR
R
IN
TCV
OS
PSRR
65
-5.3
1.0
1.0
Min
±3.25
6.5
2704A
Typ
Max
Min
2704B
Typ Max
Min
2704
Typ
Max
±6.0
12.0
5.0
6.0
1.0
1.0
-5.3
15
240
20
300
5.3
Unit
V
V
mV
mV
pA
pA
pA
pA
V
Ω
µV/°C
dB
R
S
≤
100KΩ
R
S
≤
100KΩ
0°C
≤
T
A
≤
+70°C
R
S
≤
100KΩ
0°C
≤
T
A
≤
+70°C
R
L
= 100KΩ
R
L
≥
1MΩ
R
L
≥
10KΩ
0°C
≤
T
A
≤
+70°C
R
L
= 1MΩ
0°C
≤
T
A
≤
+70°C
Test
Conditions
Dual Supply
Single Supply
R
S
≤
100KΩ
0°C
≤
T
A
≤
+70°C
T
A
= 25°C
0°C
≤
T
A
≤
+70°C
T
A
= 25°C
0°C
≤
T
A
≤
+70°C
±6.0 ±3.25
12.0
6.5
1.0
1.5
15
240
20
300
5.3
-5.3
1.0
1.0
±6.0 ±3.25
12.0
6.5
2.0
3.0
15
240
20
300
5.3
10
12
10
12
10
12
5
80
65
5
80
60
5
80
CMRR
65
83
65
83
60
83
dB
A
V
15
28
100
15
28
100
10
28
100
V/mV
V/mV
V
O
low
V
O
high
V
O
low
V
O
high
I
SC
I
S
P
D
4.90
4.99
-4.96 -4.90
-4.96 -4.90
-4.96 -4.90
4.95
4.90 4.95
4.90 4.95
-4.998 -4.99
-4.998 -4.99
-4.998 -4.99
4.998
4.99 4.998
4.99 4.998
15
5.0
6.5
15
5.0
6.5
15
5.0
6.5
V
V
mA
mA
Output Short
Circuit Current
Supply
Current
Power
Dissipation
Input
Capacitance
Bandwidth
Slew Rate
Rise time
Overshoot
Factor
V
IN
= -5V
No Load
Both amplifiers, No Load
V
S
=
±5.0V
65
65
65
mW
C
IN
1
1
1
pF
B
W
S
R
t
r
2.1
5.0
0.1
15
2.1
5.0
0.1
15
2.1
5.0
0.1
15
MHz
V/µs
µs
%
A
V
= +1 R
L
= 2.0KΩ
R
L
= 2.0KΩ
R
L
= 2.0KΩ
C
L
= 100pF
ALD2704A/ALD2704B
ALD2704
Advanced Linear Devices
2
OPERATING ELECTRICAL CHARACTERISTICS (cont'd)
T
A
= 25
°
C V
S
=
±
5.0V unless otherwise specified
2704A
Parameter
Maximum Load
Capacitance
Symbol
C
L
Min
Typ
400
4000
Max
Min
2704B
Typ
400
4000
Max
Min
2704
Typ
400
4000
Max
Unit
pF
pF
Test Conditions
Gain = 1
Gain = 5
Input Noise
Voltage
e
n
26
26
26
nV/√Hz
f =1KHz
Input Current
Noise
i
n
0.6
0.6
0.6
fA/√Hz
f =10Hz
Settling
Time
t
s
5.0
2.0
5.0
2.0
5.0
2.0
µs
µs
0.01%
0.1% A
V
= 1
R
L
= 5KΩ C
L
= 50pF
V
S
=
±
5.0V -55
°
C
≤
T
A
≤
+125
°
C unless otherwise specified
Parameter
Input Offset
Voltage
Input Offset
Current
Input Bias
Current
Power Supply
Rejection Ratio
Common Mode
Rejection Ratio
Large Signal
Voltage Gain
Output Voltage
Range
Symbol
V
OS
2704ADA
Min
Typ Max
2.0
2704BDA
Min Typ Max
4.0
Min
2704DA
Typ
Max
7.0
Unit
mV
Test Conditions
R
S
≤
100KΩ
I
OS
8.0
8.0
8.0
nA
I
B
10.0
10.0
10.0
nA
PSRR
60
75
60
75
60
75
dB
R
S
≤
100KΩ
CMRR
60
83
60
83
60
83
dB
R
S
≤
100KΩ
AV
10
25
10
25
10
25
V/mV
R
L
= 10KΩ
V
O
low
V
O
high
4.8
-4.9
4.9
-4.8
4.8
-4.9
4.9
-4.8
4.8
-4.9
4.9
-4.8
V
R
L
= 10KΩ
ALD2704A/ALD2704B
ALD2704
Advanced Linear Devices
3
Design & Operating Notes:
1. The ALD2704 CMOS operational amplifier uses a 3 gain stage
architecture and an improved frequency compensation scheme to
achieve large voltage gain, high output driving capability, and better
frequency stability. The ALD2704 is internally compensated for unity
gain stability using a novel scheme. This design produces a clean
single pole roll off in the gain characteristics while providing for more
than 70 degrees of phase margin at the unity gain frequency. A unity
gain buffer using the ALD2704 will typically drive 400pF of external
load capacitance without stability problems. In the inverting unity gain
configuration, it can drive up to 800pF of load capacitance. Compared
to other CMOS operational amplifiers, the ALD2704 is much more
resistant to parasitic oscillations.
2. The ALD2704 has complementary p-channel and n-channel input
differential stages connected in parallel to accomplish rail to rail input
common mode voltage range. With the common mode input voltage
close to the power supplies, one of the two differential stages is
switched off internally. To maintain compatibility with other opera-
tional amplifiers, this switching point has been selected to be about
1.5V above the negative supply voltage. As offset voltage trimming
on the ALD2704 is made when the input voltage is symmetrical to the
supply voltages, this internal switching does not affect a large variety
of applications such as an inverting amplifier or non-inverting amplifier
with a gain greater than 2 (10V operation), where the common mode
voltage does not make excursions below this switching point.
3. The input bias and offset currents are essentially input protection
diode reverse bias leakage currents, and are typically less than 1pA
at room temperature. This low input bias current assures that the
analog signal from the source will not be distorted by input bias
currents. For applications where source impedance is very high, it
may be necessary to limit noise and hum pickup through proper
shielding.
4. The output stage consists of class AB complementary output drivers,
capable of driving a low resistance load. The output voltage swing is
limited by the drain to source on-resistance of the output transistors as
determined by the bias circuitry, and the value of the load resistor. The
voltage follower configuration, the oscillation and resistant with the
rail- to-rail input and output feature, makes the ALD2704 an effective
analog signal buffer for medium to high source impedance sensors,
transducers, and other circuit networks.
5. The ALD2704 operational amplifier has been designed to provide
static discharge protection. Internally, the design has been carefully
implemented to minimize latch up. However, care must be exercised
when handling the device to avoid strong static fields. In using the
operational amplifier, the user is advised to power up the circuit before,
or simultaneously with, any input voltages applied and to limit input
voltages to not exceed 0.3V of the power supply voltage levels.
Alternatively, a 100KΩ or higher value resistor at the input terminals
will limit input currents to acceptable levels while causing very small
or negligible accuracy effects.
TYPICAL PERFORMANCE CHARACTERISTICS
COMMON MODE INPUT VOLTAGE RANGE
AS A FUNCTION OF SUPPLY VOLTAGE
±7
T
A
= 25°C
OPEN LOOP VOLTAGE GAIN AS A FUNCTION
OF SUPPLY VOLTAGE AND TEMPERATURE
1000
} -55°C
COMMON MODE INPUT
VOLTAGE RANGE (V)
±6
OPEN LOOP VOLTAGE
GAIN (V/mV)
} +25°C
100
} +125°C
10
RL = 10KΩ
R
L
= 5KΩ
1
0
±2
±4
SUPPLY VOLTAGE (V)
±6
±8
±5
±4
±3
±2
±2
±3
±4
±5
±6
±7
SUPPLY VOLTAGE (V)
INPUT BIAS CURRENT AS A FUNCTION
OF AMBIENT TEMPERATURE
10000
8
SUPPLY CURRENT AS A FUNCTION
OF SUPPLY VOLTAGE
7
6
5
4
3
2
1
T
A
= -55°C
-25°C
+25°C
+80°C
+125°C
INPUTS GROUNDED
OUTPUT UNLOADED
INPUT BIAS CURRENT (pA)
1000
100
10
1.0
0.1
-50
-25
0
25
50
75
100
125
SUPPLY CURRENT (mA)
V
S
=
±5.0V
0
0
±1
±2
±3
±4
±5
±6
±7
AMBIENT TEMPERATURE (°C)
SUPPLY VOLTAGE (V)
ALD2704A/ALD2704B
ALD2704
Advanced Linear Devices
4
TYPICAL PERFORMANCE CHARACTERISTICS
OUTPUT VOLTAGE SWING AS A
FUNCTION OF SUPPLY VOLTAGE
120
OPEN LOOP VOLTAGE
GAIN (dB)
±25°C ≤
T
A
≤
125°C
RL = 10KΩ
OPEN LOOP VOLTAGE AS A FUNCTION
OF FREQUENCY
100
80
60
40
20
0
-20
±7
OUTPUT VOLTAGE SWING (V)
±6
±5
±4
±3
±2
0
PHASE SHIFT IN DEGREES
V
S
=
±5.0V
T
A
= 25°C
0
45
90
135
180
1
10
100
1K
10K
100K
1M
10M
R
L
= 10KΩ
R
L
= 2KΩ
±1
±2
±3
±4
±5
±6
±7
SUPPLY VOLTAGE (V)
FREQUENCY (Hz)
INPUT OFFSET VOLTAGE AS A FUNCTION
OF AMBIENT TEMPERATURE
REPRESENTATIVE UNITS
INPUT OFFSET VOLTAGE (mV)
V
S
=
±5.0V
INPUT OFFSET VOLTAGE AS A FUNCTION
OF COMMON MODE INPUT VOLTAGE
15
INPUT OFFSET VOLTAGE (mV)
+5
+4
+3
+2
+1
0
-1
-2
-3
-4
-5
-50
-25
0
+25
+50
10
5
0
-5
-10
-15
V
S
=
±5.0V
T
A
= 25ºC
+75
+100 +125
-4
-2
0
+2
+4
+6
AMBIENT TEMPERATURE (°C)
COMMON MODE INPUT VOLTAGE (V)
OPEN LOOP VOLTAGE GAIN AS A
FUNCTION OF LOAD RESISTANCE
1000
LARGE - SIGNAL TRANSIENT
RESPONSE
5V/div
V
S
=
±5.0V
T
A
= 25°C
R
L
= 1KΩ
C
L
= 50pF
OPEN LOOP VOLTAGE
GAIN (V/mV)
100
V
S
=
±5.0V
T
A
= 25°C
10
5V/div
2µs/div
1
1K
10K
100K
1000K
LOAD RESISTANCE (Ω)
VOLTAGE NOISE DENSITY AS A
FUNCTION OF FREQUENCY
150
SMALL - SIGNAL TRANSIENT
RESPONSE
100mV/div
V
S
=
±
5.0V
T
A
= 25°C
R
L
= 1.0KΩ
C
L
= 50pF
VOLTAGE NOISE DENSITY
(nV/
√
Hz)
125
100
75
50
25
0
10
100
1K
10K
100K
1000K
50mV/div
V
S
=
±5.0V
T
A
= 25°C
1µs/div
ALD2704A/ALD2704B
ALD2704
FREQUENCY (Hz)
Advanced Linear Devices
5
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