LOW POWER, SINGLE-SUPPLY, RAIL-TO-RAIL
OPERATIONAL AMPLIFIERS
Micro
Amplifier
TM
Series
2000 Burr-Brown Corporation
PDS-1486A
Printed in U.S.A. April, 2000
FEATURES
q
RAIL-TO-RAIL INPUT
q
RAIL-TO-RAIL OUTPUT (within 1mV)
q
LOW QUIESCENT CURRENT: 150
A typ
q
Micro
SIZE PACKAGES
SOT23-5
MSOP-8
TSSOP-14
q
GAIN-BANDWIDTH
OPA344: 1MHz, G
1
OPA345: 3MHz, G
5
q
SLEW RATE
OPA344: 0.8V/
s
OPA345: 2V/
s
q
THD + NOISE: 0.006%
APPLICATIONS
q
PCMCIA CARDS
q
DATA ACQUISITION
q
PROCESS CONTROL
q
AUDIO PROCESSING
q
COMMUNICATIONS
q
ACTIVE FILTERS
q
TEST EQUIPMENT
DESCRIPTION
The OPA344 and OPA345 series rail-to-rail CMOS
operational amplifiers are designed for precision, low-
power, miniature applications. The OPA344 is unity
gain stable, while the OPA345 is optimized for gains
greater than or equal to five, and has a gain-bandwidth
product of 3MHz.
The OPA344 and OPA345 are optimized to operate on
a single supply from 2.5V and up to 5.5V with an input
common-mode voltage range that extends 300mV
beyond the supplies. Quiescent current is only
250
A (max).
Rail-to-rail input and output make them ideal for driving
sampling analog-to-digital converters. They are also well
suited for general purpose and audio applicaitons and
providing I/V conversion at the output of D/A converters.
Single, dual and quad versions have identical specs for
design flexibility.
A variety of packages are available. All are specified for
operation from 40C to 85C. A SPICE macromodel is
available for design analysis.
OPA345
OPA2345
OPA4345
OPA344
OPA2344
OPA4344
1
2
3
5
4
V+
In
Out
V
+In
OPA344, OPA345
SOT23-5
1
2
3
4
8
7
6
5
NC
V+
Out
NC
NC
In
+In
V
OPA344, OPA345
SO-8, 8-Pin DIP (OPA344 Only)
1
2
3
4
8
7
6
5
V+
Out B
In B
+In B
Out A
In A
+In A
V
OPA2344, OPA2345
SO-8, MSOP-8, 8-Pin DIP (OPA2344 Only)
A
B
1
2
3
4
5
6
7
14
13
12
11
10
9
8
Out D
In D
+In D
V
+In C
In C
Out C
Out A
In A
+In A
+V
+In B
In B
Out B
OPA4344, OPA4345
TSSOP-14, SO-14, 14-PIn DIP (OPA4344 Only)
A
D
B
C
International Airport Industrial Park Mailing Address: PO Box 11400, Tucson, AZ 85734 Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 Tel: (520) 746-1111
Twx: 910-952-1111 Internet: http://www.burr-brown.com/ Cable: BBRCORP Telex: 066-6491 FAX: (520) 889-1510 Immediate Product Info: (800) 548-6132
OPA342
OPA4344
OPA344
OPA345
For most current data sheet and other product
information, visit www.burr-brown.com
SBOS107
2
OPA344, 2344, 4344
OPA345, 2345, 4345
SPECIFICATIONS: V
S
= 2.7V to 5.5V
At T
A
= +25
C, R
L
= 10k
connected to V
S
/ 2 and V
OUT
= V
S
/ 2, unless otherwise noted.
Boldface limits apply over the temperature range, T
A
= 40
C to +85
C.
OPA344NA, UA, PA
OPA2344EA, UA, PA
OPA4344EA, UA, PA
PARAMETER
CONDITION
MIN
TYP
MAX
UNITS
OFFSET VOLTAGE
Input Offset Voltage
V
OS
V
S
= +5.5V, V
CM
= V
S
/2
0.2
1
mV
Over Temperature
0.8
1.2
mV
vs Temperature
dV
OS
/dT
3
V/
C
vs Power Supply
PSRR
V
S
= 2.7V to 5.5V, V
CM
< (V+) -1.8V
30
200
V/V
Over Temperature
V
S
= 2.7V to 5.5V, V
CM
< (V+) -1.8V
250
V/V
Channel Separation, dc
0.2
V/V
f = 1kHz
130
dB
INPUT BIAS CURRENT
Input Bias Current
I
B
0.2
10
pA
Over Temperature
See Typical Curve
pA
Input Offset Current
I
OS
0.2
10
pA
NOISE
Input Voltage Noise
f = 0.1 to 50kHz
8
Vrms
Input Voltage Noise Density
e
n
f = 10kHz
30
nV/
Hz
Current Noise Density
i
n
f = 10kHz
0.5
fA/
Hz
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
V
CM
0.3
(V+) + 0.3
V
Common-Mode Rejection Ratio
CMRR
V
S
= +5.5V, 0.3V
< V
CM
< (V+)-1.8
76
92
dB
Over Temperature
V
S
= +5.5V, 0.3V
< V
CM
< (V+)-1.8
74
dB
Common-Mode Rejection
CMRR
V
S
= +5.5V, 0.3V
< V
CM
< 5.8V
70
84
dB
Over Temperature
V
S
= +5.5V, 0.3V
< V
CM
< 5.8V
68
dB
Common-Mode Rejection
CMRR
V
S
= +2.7V, 0.3V
< V
CM
< 3V
66
80
dB
Over Temperature
V
S
= +2.7V, 0.3V
< V
CM
< 3V
64
dB
INPUT IMPEDANCE
Differential
10
13
|| 3
|| pF
Common-Mode
10
13
|| 6
|| pF
OPEN-LOOP GAIN
Open-Loop Voltage Gain
A
OL
R
L
= 100k
, 10mV < V
O
< (V+) 10mV
104
122
dB
Over Temperature
R
L
= 100k
, 10mV < V
O
< (V+) 10mV
100
dB
R
L
= 5k
, 400mV < V
O
< (V+) 400mV
96
120
dB
Over Temperature
R
L
= 5k
, 400mV < V
O
< (V+) 400mV
90
dB
FREQUENCY RESPONSE
C
L
= 100pF
Gain-Bandwidth Product
GBW
1
MHz
Slew Rate
SR
0.8
V/
s
Settling Time, 0.1%
V
S
= 5.5V, 2V Step
5
s
0.01%
V
S
= 5.5V, 2V Step
8
s
Overload Recovery Time
V
IN
G = V
S
2.5
s
Total Harmonic Distortion + Noise
THD+N
V
S
= 5.5V, V
O
= 3Vp-p, G = 1, f = 1kHz
0.006
%
OUTPUT
Voltage Output Swing from Rail
(1)
R
L
= 100k
, A
OL
96dB
1
mV
R
L
= 100k
,
A
OL
104dB
3
10
mV
Over Temperature
R
L
= 100k
,
A
OL
100dB
10
mV
R
L
= 5k
, A
OL
96dB
40
400
mV
Over Temperature
R
L
= 5k
,
A
OL
90dB
400
mV
Short-Circuit Current
I
SC
15
mA
Capacitive Load Drive
C
LOAD
See Typical Curve
POWER SUPPLY
Specified Voltage Range
V
S
2.7
5.5
V
Operating Voltage Range
2.5 to 5.5
V
Quiescent Current (per amplifier)
I
Q
V
S
= 5.5V, I
O
= 0
150
250
A
Over Temperature
300
A
TEMPERATURE RANGE
Specified Range
40
85
C
Operating Range
55
125
C
Storage Range
65
150
C
Thermal Resistance
JA
SOT23-5 Surface Mount
200
C/W
MSOP-8 Surface Mount
150
C/W
8-Pin DIP
100
C/W
SO-8 Surface Mount
150
C/W
TSSOP-14 Surface Mount
100
C/W
14-Pin DIP
80
C/W
SO-14 Surface Mount
100
C/W
NOTE: (1) Output voltage swings are measured between the output and power-supply rails.
3
OPA344, 2344, 4344
OPA345, 2345, 4345
SPECIFICATIONS: V
S
= 2.7V to 5.5V
At T
A
= +25
C, R
L
= 10k
connected to V
S
/ 2 and V
OUT
= V
S
/2, unless otherwise noted.
Boldface limits apply over the temperature range, T
A
= 40
C to +85
C.
OPA345NA, UA
OPA2345EA, UA
OPA4345EA, UA
PARAMETER
CONDITION
MIN
TYP
MAX
UNITS
OFFSET VOLTAGE
Input Offset Voltage
V
OS
V
S
= +5.5V, V
CM
= V
S
/2
0.2
1
mV
Over Temperature
0.8
1.2
mV
vs Temperature
dV
OS
/dT
3
V/
C
vs Power Supply
PSRR
V
S
= 2.7V to 5.5V, V
CM
< (V+) -1.8V
30
200
V/V
Over Temperature
V
S
= 2.7V to 5.5V, V
CM
< (V+) -1.8V
250
V/V
Channel Separation, dc
0.2
V/V
f = 1kHz
130
dB
INPUT BIAS CURRENT
Input Bias Current
I
B
0.2
10
pA
Over Temperature
See Typical Curve
pA
Input Offset Current
I
OS
0.2
10
pA
NOISE
Input Voltage Noise
f = 0.1 to 50kHz
8
Vrms
Input Voltage Noise Density
e
n
f = 10kHz
30
nV/
Hz
Current Noise Density
i
n
f = 10kHz
0.5
fA/
Hz
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
V
CM
0.3
(V+) + 0.3
V
Common-Mode Rejection Ratio
CMRR
V
S
= +5.5V, 0.3V
< V
CM
< (V+)-1.8
76
92
dB
Over Temperature
V
S
= +5.5V, 0.3V
< V
CM
< (V+)-1.8
74
dB
Common-Mode Rejection Ratio
CMRR
V
S
= +5.5V, 0.3V
< V
CM
< 5.8V
70
84
dB
Over Temperature
V
S
= +5.5V, 0.3V
< V
CM
< 5.8V
68
dB
Common-Mode Rejection Ratio
CMRR
V
S
= +2.7V, 0.3V
< V
CM
< 3V
66
80
dB
Over Temperature
V
S
= +2.7V, 0.3V
< V
CM
< 3V
64
dB
INPUT IMPEDANCE
Differential
10
13
|| 3
|| pF
Common-Mode
10
13
|| 6
|| pF
OPEN-LOOP GAIN
Open-Loop Voltage Gain
A
OL
R
L
= 100k
, 10mV < V
O
< (V+) 10mV
104
122
dB
Over Temperature
R
L
= 100k
, 10mV < V
O
< (V+) 10mV
100
dB
R
L
= 5k
, 400mV < V
O
< (V+) 400mV
96
120
dB
Over Temperature
R
L
= 5k
, 400mV < V
O
< (V+) 400mV
90
dB
FREQUENCY RESPONSE
C
L
= 100pF
Gain-Bandwidth Product
GBW
3
MHz
Slew Rate
SR
2
V/
s
Settling Time, 0.1%
G = 5, 2V Output Step
1.5
s
0.01%
G = 5, 2V Output Step
1.6
s
Overload Recovery Time
V
IN
G = V
S
2.5
s
Total Harmonic Distortion + Noise
THD+N
V
S
= 5.5V, V
O
= 2.5Vp-p, G = 5, f = 1kHz
0.006
%
OUTPUT
Voltage Output Swing from Rail
(1)
R
L
= 100k
, A
OL
96dB
1
mV
R
L
= 100k
,
A
OL
104dB
3
10
mV
Over Temperature
R
L
= 100k
,
A
OL
100dB
10
mV
R
L
= 5k
, A
OL
96dB
40
400
mV
Over Temperature
R
L
= 5k
,
A
OL
90dB
400
mV
Short-Circuit Current
I
SC
15
mA
Capacitive Load Drive
C
LOAD
See Typical Curve
POWER SUPPLY
Specified Voltage Range
V
S
2.7
5.5
V
Operating Voltage Range
2.5 to 5.5
V
Quiescent Current (per amplifier)
I
Q
V
S
= 5.5V, I
O
= 0
150
250
A
Over Temperature
300
A
TEMPERATURE RANGE
Specified Range
40
85
C
Operating Range
55
125
C
Storage Range
65
150
C
Thermal Resistance
JA
SOT23-5 Surface Mount
200
C/W
MSOP-8 Surface Mount
150
C/W
SO-8 Surface Mount
150
C/W
TSSOP-14 Surface Mount
100
C/W
SO-14 Surface Mount
100
C/W
NOTE: (1) Output voltage swings are measured between the output and power-supply rails.
4
OPA344, 2344, 4344
OPA345, 2345, 4345
PACKAGE
SPECIFIED
DRAWING
TEMPERATURE
PACKAGE
ORDERING
TRANSPORT
PRODUCT
PACKAGE
NUMBER
RANGE
MARKING
NUMBER
(1)
MEDIA
OPA344NA
SOT23-5
331
40
C to +85
C
B44
OPA344NA/250
Tape and Reel
"
"
"
"
"
OPA344NA/3K
Tape and Reel
OPA344UA
SO-8
182
40
C to +85
C
OPA344UA
OPA344UA
Rails
"
"
"
"
"
OPA344UA /2K5
Tape and Reel
OPA344PA
8-Pin Dip
006
40
C to +85
C
OPA344PA
OPA344PA
Rails
OPA2344EA
MSOP-8
337
40
C to +85
C
C44
OPA2344EA /250
Tape and Reel
"
"
"
"
"
OPA2344EA /2K5
Tape and Reel
OPA2344UA
SO-8
182
40
C to +85
C
OPA2344UA
OPA2344UA
Rails
"
"
"
"
"
OPA2344UA/2K5
Tape and Reel
OPA2344PA
8-Pin DIP
006
40
C to +85
C
OPA2344PA
OPA2344PA
Rails
OPA4344EA
TSSOP-14
357
40
C to +85
C
OPA4344EA
OPA4344EA /250
Rails
"
"
"
"
"
OPA4344EA /2K5
Tape and Reel
OPA4344UA
SO-14
235
40
C to +85
C
OPA4344UA
OPA4344UA
Rails
"
"
"
"
"
OPA4344UA/2K5
Tape and Reel
OPA4344PA
14-Pin DIP
010
40
C to +85
C
OPA4344PA
OPA4344PA
Rails
OPA345NA
SOT23-5
331
40
C to +85
C
A45
OPA345NA/250
Tape and Reel
"
"
"
"
"
OPA345NA/3K
Tape and Reel
OPA345UA
SO-8
182
40
C to +85
C
OPA345UA
OPA345UA
Rails
"
"
"
"
"
OPA345UA/2K5
Tape and Reel
OPA2345EA
MSOP-8
337
40
C to +85
C
B45
OPA2345EA/250
Tape and Reel
"
"
"
"
"
OPA2345EA /2K5
Tape and Reel
OPA2345UA
SO-8
182
40
C to +85
C
OPA2345UA
OPA2345UA
Rails
"
"
"
"
"
OPA2345UA/2K5
Tape and Reel
OPA4345EA
TSSOP-14
357
40
C to +85
C
OPA4345EA
OPA4345EA/250
Tape and Reel
"
"
"
"
"
OPA4345EA /2K5
Tape and Reel
OPA4345UA
SO-14
235
40
C to +85
C
OPA4345UA
OPA4345UA
Rails
"
"
"
"
"
OPA4345UA/2K5
Tape and Reel
NOTE: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces
of "OPA344UA/2K5" will get a single 2500-piece Tape and Reel.
PACKAGE/ORDERING INFORMATION
Supply Voltage, V+ to V- ................................................................... 7.5V
Signal Input Terminals, Voltage
(2)
..................... (V) 0.5V to (V+) +0.5V
Current
(2)
.................................................... 10mA
Output Short-Circuit
(3)
.............................................................. Continuous
Operating Temperature .................................................. 55
C to +125
C
Storage Temperature ..................................................... 65
C to +150
C
Junction Temperature ...................................................................... 150
C
Lead Temperature (soldering, 10s) ................................................. 300
C
ESD Tolerance (Human Body Model) ............................................ 4000V
NOTES: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum conditions for extended periods may
degrade device reliability. These are stress ratings only. Functional opera-
tion of the device at these conditions, or beyond the specified operating
conditions, is not implied. (2) Input terminals are diode-clamped to the power
supply rails. Input signals that can swing more than 0.5V beyond the supply
rails should be current-limited to 10mA or less. (3) Short-circuit to ground,
one amplifier per package.
ABSOLUTE MAXIMUM RATINGS
(1)
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage. ESD damage
can range from subtle performance degradation to complete
device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.
5
OPA344, 2344, 4344
OPA345, 2345, 4345
TYPICAL PERFORMANCE CURVES
At T
A
= +25
C, V
S
= +5V, and R
L
= 10k
connected to V
S
/2, unless otherwise noted.
POWER SUPPLY AND COMMON-MODE
REJECTION RATIO vs FREQUENCY
10
Rejection Ratio (dB)
Frequency (Hz)
100
1k
10k
100k
100
80
60
40
20
10
+PSRR
CMRR
PSRR
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
100k
Maximum Output Voltage (Vp-p)
Frequency (Hz)
1M
10M
6
5
4
3
2
1
0
OPA344
V
S
= +2.7V
V
S
= +5.5V
V
S
=
+5V
OPA345
CHANNEL SEPARATION vs FREQUENCY
100
Channel Separation (dB)
Frequency (Hz)
1k
10k
100k
1M
140
120
100
80
60
Dual and quad devices.
G = 1, all channels.
Quad measured channel
A to D or B to C--other
combinations yield improved
rejection.
VOLTAGE AND CURRENT NOISE
SPECTRAL DENSITY vs FREQUENCY
1
Voltage Noise (nV/
Hz)
Frequency (Hz)
10
100
1k
10k
100k
1M
10M
10000
1000
100
10
Current Noise (fA/
Hz)
100
10
1
0.1
V
N
I
N
OPEN-LOOP GAIN/PHASE vs FREQUENCY
0.1
1
Gain (dB)
0
30
60
90
120
150
180
Phase (
)
Frequency (Hz)
10
100
1k
10k
100k
1M
10M
120
100
80
60
40
20
0
Gain
Phase
OPA345
OPEN-LOOP GAIN/PHASE vs FREQUENCY
0.1
1
Gain (dB)
0
30
60
90
120
150
180
Phase (
)
Frequency (Hz)
10
100
1k
10k
100k
1M
10M
120
100
80
60
40
20
0
Gain
Phase
OPA344
6
OPA344, 2344, 4344
OPA345, 2345, 4345
TYPICAL PERFORMANCE CURVES
(Cont.)
At T
A
= +25
C, V
S
= +5V, and R
L
= 10k
connected to V
S
/2, unless otherwise noted.
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
20
THD+N (%)
Frequency (Hz)
100
1k
10k
20k
1
0.1
0.010
0.001
OPA344: G = 1
OPA345: G = 5
OPEN-LOOP GAIN, COMMON-MODE REJECTION RATIO,
AND POWER-SUPPLY REJECTION vs TEMPERATURE
A
OL
75
A
OL
, CMRR, PSRR (dB)
Temperature (
C)
25
0
25
50
50
125
75
100
140
120
100
80
60
40
20
0
CMRR
PSRR
INPUT BIAS CURRENT vs TEMPERATURE
75
Input Bias Current (pA)
Temperature (
C)
25
0
25
50
100
50
75
125
10000
1000
100
10
1
0.1
QUIESCENT CURRENT AND
SHORT-CIRCUIT CURRENT vs TEMPERATURE
75
50
0
Quiescent Current (
A)
Temperature (
C)
25
50
100
I
Q
+I
SC
I
SC
75
25
125
200
175
150
135
100
75
50
25
0
Short-Circuit Current (mA)
40
35
30
25
20
15
10
5
0
SLEW RATE vs TEMPERATURE
75
Slew Rate (V/
s)
Temperature (
C)
25
0
SR
SR
SR+
SR+
75
50
25
50
125
100
3.0
2.5
2.0
1.5
1.0
0.5
0
OPA345
OPA344
INPUT BIAS CURRENT
vs COMMON-MODE VOLTAGE
1
Input Bias Current (pA)
Common-Mode Voltage (V)
0
1
2
4
3
5
6
6
4
2
0
2
4
6
V+
Supply
V
Supply
Input voltage
0.3V
can cause op amp output
to lock up. See text.
7
OPA344, 2344, 4344
OPA345, 2345, 4345
TYPICAL PERFORMANCE CURVES
(Cont.)
At T
A
= +25
C, V
S
= +5V, and R
L
= 10k
connected to V
S
/2, unless otherwise noted.
QUIESCENT CURRENT AND
SHORT-CIRCUIT CURRENT vs SUPPLY VOLTAGE
Quiescent Current (
A)
Supply Voltage (V)
2
3
4
5
6
+I
SC
I
SC
I
Q
160
155
150
145
140
Short-Circuit Current (mA)
20
15
10
5
0
OPEN-LOOP GAIN vs OUTPUT VOLTAGE SWING
140
130
120
110
100
Open-Loop Gain (dB)
Output Voltage Swing from Rail (mV)
120
100
80
60
40
20
0
R
L
= 5k
R
L
= 100k
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
0
Output Voltage (V)
Output Current (mA)
5
10
15
20
V+
(V+) 1
(V+) 2
2
1
0
85
C
25
C
40
C
85
C
25
C
40
C
QUIESCENT CURRENT
PRODUCTION DISTRIBUTION
Population
Quiescent Current (
A)
100
115
130
145
160
175
190
205
220
235
250
OFFSET VOLTAGE
PRODUCTION DISTRIBUTION
Population
Offset Voltage (
V)
1000
800
600
400
200
0
200
400
600
800
1000
OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
Population
Offset Voltage Drift (
V/
C)
10
8
6
4
2
0
2
4
6
8
10
8
OPA344, 2344, 4344
OPA345, 2345, 4345
TYPICAL PERFORMANCE CURVES
(Cont.)
At T
A
= +25
C, V
S
= +5V, and R
L
= 10k
connected to V
S
/2, unless otherwise noted.
70
60
50
40
30
20
10
0
Small-Signal Overshoot (%)
SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE
100
1k
10k
10
Load Capacitance (pF)
G = 5
G = 10, +10
G = +5
OPA345
20mV/div
5
s/div
SMALL-SIGNAL STEP RESPONSE: OPA345
G = +5, R
L
= 10k
, C
L
= 100pF
OPA345
20mV/div
5
s/div
SMALL-SIGNAL STEP RESPONSE: OPA344
G = +1, R
L
= 10k
, C
L
= 100pF
OPA344
5
s/div
LARGE-SIGNAL STEP RESPONSE: OPA344
G = +1, R
L
= 10k
, C
L
= 100pF
1V/div
OPA344
5
s/div
LARGE-SIGNAL STEP RESPONSE: OPA345
G = +5, R
L
= 10k
, C
L
= 100pF
1V/div
OPA345
SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE
1
Small-Signal Overshoot (%)
Load Capacitance (pF)
10
100
1k
10k
G = 1
G = 5
50
45
40
35
30
25
20
15
10
5
0
OPA344
G = +5
G = +1
9
OPA344, 2344, 4344
OPA345, 2345, 4345
APPLICATIONS INFORMATION
OPA344 series op amps are unity gain stable and can operate
on a single supply, making them highly versatile and easy to
use. OPA345 series op amps are optimized for applications
requiring higher speeds with gains of 5 or greater.
Rail-to-rail input and output swing significantly increases
dynamic range, especially in low supply applications. Figure
1 shows the input and output waveforms for the OPA344 in
unity-gain configuration. Operation is from V
S
= +5V with
a 10k
load connected to V
S
/2. The input is a 5Vp-p
sinusoid. Output voltage is approximately 4.997Vp-p.
Power supply pins should be by passed with 0.01pF ceramic
capacitors.
OPERATING VOLTAGE
OPA344 and OPA345 series op amps are fully specified and
guaranteed from +2.7V to +5.5V. In addition, many specifi-
cations apply from 40C to +85C. Parameters that vary
significantly with operating voltages or temperature are
shown in the Typical Performance Curves.
RAIL-TO-RAIL INPUT
The input common-mode voltage range of the OPA344 and
OPA345 series extends 300mV beyond the supply rails.
This is achieved with a complementary input stage--an N-
channel input differential pair in parallel with a P-channel
differential pair (see Figure 2). The N-channel pair is active
for input voltages close to the positive rail, typically (V+)
1.3V to 300mV above the positive supply, while the P-
channel pair is on for inputs from 300mV below the negative
supply to approximately (V+) 1.3V. There is a small
transition region, typically (V+) 1.5V to (V+) 1.1V, in
which both pairs are on. This 400mV transition region can
vary 300mV with process variation. Thus, the transition
region (both stages on) can range from (V+) 1.8V to (V+)
1.4V on the low end, up to (V+) 1.2V to (V+) 0.8V on
the high end. Within the 400mV transition region PSRR,
CMRR, offset voltage, offset drift, and THD may be de-
graded compared to operation outside this region. For more
information on designing with rail-to-rail input op amps, see
Figure 3 "Design Optimization with Rail-to-Rail Input Op
Amps."
FIGURE 2. Simplified Schematic.
V
BIAS1
V
BIAS2
V
IN
+
V
IN
Class AB
Control
Circuitry
V
O
V
(Ground)
V+
Reference
Current
FIGURE 1. Rail-to-Rail Input and Output.
5
s/div
1V/div
Output (inverted on scope)
Input
G = +1, V
S
= +5V
5V
0V
10
OPA344, 2344, 4344
OPA345, 2345, 4345
COMMON-MODE REJECTION
The CMRR for the OPA344 and OPA345 is specified in
several ways so the best match for a given application may
be used. First, the CMRR of the device in the common-mode
range below the transition region (V
CM
< (V+) 1.8V) is
given. This specification is the best indicator of the capabil-
ity of the device when the application requires use of one of
the differential input pairs. Second, the CMRR at V
S
= 5.5V
over the entire common-mode range is specified. Third, the
CMRR at V
S
= 2.7V over the entire common-mode range is
provided. These last two values include the variations seen
through the transition region.
INPUT VOLTAGE BEYOND THE RAILS
If the input voltage can go more than 0.3V below the
negative power supply rail (single-supply ground), special
precautions are required. If the input voltage goes suffi-
ciently negative, the op amp output may lock up in an
inoperative state. A Schottky diode clamp circuit will pre-
vent this--see Figure 4. The series resistor prevents exces-
sive current (greater than 10mA) in the Schottky diode and
in the internal ESD protection diode, if the input voltage can
exceed the positive supply voltage. If the signal source is
limited to less than 10mA, the input resistor is not required.
RAIL-TO-RAIL OUTPUT
A class AB output stage with common-source transistors is
used to achieve rail-to-rail output. This output stage is
capable of driving 600
loads connected to any potential
between V+ and ground. For light resistive loads (> 50k
),
the output voltage can typically swing to within 1mV from
supply rail. With moderate resistive loads (2k
to 50k
),
the output can swing to within a few tens of milli-volts from
the supply rails while maintaining high open-loop gain. See
the typical performance curve "Output Voltage Swing vs
Output Current."
V
O
V
IN
V
B
V+
Non-Inverting Gain
V
CM
= V
IN
V
O
V
B
V
IN
V+
Inverting Amplifier
V
CM
= V
B
V
O
V
IN
V+
G = 1 Buffer
V
CM
= V
IN
= V
O
FIGURE 3. Design Optimization with Rail-to-Rail Input Op Amps.
Rail-to-rail op amps can be used in virtually any op amp
configuration. To achieve optimum performance, how-
ever, applications using these special double-input-stage
op amps may benefit from consideration of their special
behavior.
In many applications, operation remains within the com-
mon-mode range of only one differential input pair.
However some applications exercise the amplifier through
the transition region of both differential input stages.
Although the two input stages are laser trimmed for
excellent matching, a small discontinuity may occur in
this transition. Careful selection of the circuit configura-
tion, signal levels and biasing can often avoid this transi-
tion region.
DESIGN OPTIMIZATION WITH RAIL-TO-RAIL INPUT OP AMPS
With a unity-gain buffer, for example, signals will traverse
this transition at approximately 1.3V below V+ supply
and may exhibit a small discontinuity at this point.
The common-mode voltage of the non-inverting ampli-
fier is equal to the input voltage. If the input signal always
remains less than the transition voltage, no discontinuity
will be created. The closed-loop gain of this configura-
tion can still produce a rail-to-rail output.
Inverting amplifiers have a constant common-mode volt-
age equal to V
B
. If this bias voltage is constant, no
discontinuity will be created. The bias voltage can gener-
ally be chosen to avoid the transition region.
FIGURE 4. Input Current Protection for Voltages Exceed-
ing the Supply Voltage.
1k
OPA344
10mA max
V+
V
IN
V
OUT
I
OVERLOAD
IN5818
Schottky diode is required only
if input voltage can go more
than 0.3V below ground.
CAPACITIVE LOAD AND STABILITY
The OPA344 in a unity-gain configuration and the OPA345
in gains greater than 5 can directly drive up to 250pF pure
capacitive load. Increasing the gain enhances the amplifier's
ability to drive greater capacitive loads. See the typical
11
OPA344, 2344, 4344
OPA345, 2345, 4345
performance curve "Small-Signal Overshoot vs Capacitive
Load." In unity-gain configurations, capacitive load drive
can be improved by inserting a small (10
to 20
) resistor,
R
S
, in series with the output, as shown in Figure 5. This
significantly reduces ringing while maintaining dc perfor-
mance for purely capacitive loads. However, if there is a
resistive load in parallel with the capacitive load, a voltage
divider is created, introducing a dc error at the output and
slightly reducing the output swing. The error introduced is
proportional to the ratio R
S
/R
L
, and is generally negligible.
FIGURE 6. OPA344 in Noninverting Configuration Driving ADS7822.
FIGURE 7. Speech Bandpass Filtered Data Acquisition System.
DRIVING A/D CONVERTERS
The OPA344 and OPA345 series op amps are optimized for
driving medium-speed sampling A/D converters. The
OPA344 and OPA345 op amps buffer the A/D's input
capacitance and resulting charge injection while providing
signal gain.
Figures 6 shows the OPA344 in a basic noninverting con-
figuration driving the ADS7822. The ADS7822 is a 12-bit,
micro-power sampling converter in the MSOP-8 package.
When used with the low-power, miniature packages of the
OPA344, the combination is ideal for space-limited, low-
power applications. In this configuration, an RC network at
the A/D's input can be used to filter charge injection.
Figure 7 shows the OPA2344 driving an ADS7822 in a
speech bandpass filtered data acquisition system. This small,
low-cost solution provides the necessary amplification and
signal conditioning to interface directly with an electret
microphone. This circuit will operate with V
S
= +2.7V to
+5V with less than 500
A quiescent current.
FIGURE 5. Series Resistor in Unity-Gain Configuration
Improves Capacitive Load Drive.
10
to
20
OPA344
V+
V
IN
V
OUT
R
S
R
L
C
L
C
3
33pF
V+
GND
3
1
8
4
5
6
7
IN
+IN
2
C
2
DCLOCK
Serial
Interface
1000pF
R
1
1.5k
R
4
20k
R
5
20k
R
6
100k
R
8
150k
R
9
510k
R
7
51k
D
OUT
V
REF
V+ = +2.7V to 5V
CS/SHDN
C
1
1000pF
Electret
Microphone
(1)
G = 100
Passband 300Hz to 3kHz
R
3
1M
R
2
1M
NOTE: (1) Electret microphone
powered by R
1
.
ADS7822
12-Bit A/D
1/2
OPA2344
1/2
OPA2344
ADS7822
12-Bit A/D
DCLOCK
D
OUT
CS/SHDN
OPA344
+5V
V
IN
V+
2
+In
3
In
V
REF
8
4
GND
Serial
Interface
1
0.1
F
0.1
F
7
6
5
NOTE: A/D Input = 0 to V
REF
V
IN
= 0V to 5V for
0V to 5V output.
RC network filters high frequency noise.
500
3300pF
PACKAGING INFORMATION
ORDERABLE DEVICE
STATUS(1)
PACKAGE TYPE
PACKAGE DRAWING
PINS
PACKAGE QTY
OPA2344EA/250
ACTIVE
VSSOP
DGK
8
250
OPA2344EA/2K5
ACTIVE
VSSOP
DGK
8
2500
OPA2344PA
ACTIVE
PDIP
P
8
50
OPA2344UA
ACTIVE
SOIC
D
8
100
OPA2344UA/2K5
ACTIVE
SOIC
D
8
2500
OPA2345EA/250
ACTIVE
VSSOP
DGK
8
250
OPA2345EA/2K5
ACTIVE
VSSOP
DGK
8
2500
OPA2345UA
ACTIVE
SOIC
D
8
100
OPA2345UA/2K5
ACTIVE
SOIC
D
8
2500
OPA344NA/250
ACTIVE
SOP
DBV
5
250
OPA344NA/3K
ACTIVE
SOP
DBV
5
3000
OPA344PA
ACTIVE
PDIP
P
8
50
OPA344UA
ACTIVE
SOIC
D
8
100
OPA344UA/2K5
ACTIVE
SOIC
D
8
2500
OPA345NA/250
ACTIVE
SOP
DBV
5
250
OPA345NA/3K
ACTIVE
SOP
DBV
5
3000
OPA345UA
ACTIVE
SOIC
D
8
100
OPA345UA/2K5
ACTIVE
SOIC
D
8
2500
OPA4344EA/250
ACTIVE
TSSOP
PW
14
250
OPA4344EA/2K5
ACTIVE
TSSOP
PW
14
2500
OPA4344PA
ACTIVE
PDIP
N
14
25
OPA4344UA
ACTIVE
SOIC
D
14
58
OPA4344UA/2K5
ACTIVE
SOIC
D
14
2500
OPA4345EA/250
ACTIVE
TSSOP
PW
14
250
OPA4345EA/2K5
ACTIVE
TSSOP
PW
14
2500
OPA4345UA
ACTIVE
SOIC
D
14
58
OPA4345UA/2K5
ACTIVE
SOIC
D
14
2500
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
PACKAGE OPTION ADDENDUM
www.ti.com
3-Oct-2003
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