FEATURES
DRAIL-TO-RAIL INPUT
DRAIL-TO-RAIL OUTPUT (within 10mV)
DWIDE BANDWIDTH: 38MHz
DHIGH SLEW RATE: 22V/µs
DLOW NOISE: 5nV/Hz
DLOW THD+NOISE: 0.0006%
DUNITY-GAIN STABLE
DMicroSIZE PACKAGES
DSINGLE, DUAL, AND QUAD
APPLICATIONS
DCELL PHONE PA CONTROL LOOPS
DDRIVING A/D CONVERTERS
DVIDEO PROCESSING
DDATA ACQUISITION
DPROCESS CONTROL
DAUDIO PROCESSING
DCOMMUNICATIONS
DACTIVE FILTERS
DTEST EQUIPMENT
DESCRIPTION
The OPA350 series rail-to-rail CMOS operational
amplifiers are optimized for low voltage, single-supply
operation. Rail-to-rail input/output, low noise (5nV/Hz),
and high speed operation (38MHz, 22V/µs) make them
ideal for driving sampling Analog-to-Digital (A/D)
converters. They are also well suited for cell phone PA
control loops and video processing (75 drive capability)
as well as audio and general purpose applications. Single,
dual, and quad versions have identical specifications for
maximum design flexibility.
The OPA350 series operates on a single supply as low as
2.5V with an input common-mode voltage range that
extends 300mV below ground and 300mV above the
positive supply. Output voltage swing is to within 10mV of
the supply rails with a 10k load. Dual and quad designs
feature completely independent circuitry for lowest
crosstalk and freedom from interaction.
The single (OPA350) and dual (OPA2350) come in the
miniature MSOP-8 surface mount, SO-8 surface mount,
and DIP-8 packages. The quad (OPA4350) packages are
the space-saving SSOP-16 surface mount and SO-14
surface moun t . A l l a r e s p e c i f i e d f r o m 4 0 °C to +85°C and
operate from −55°C to +150°C.
SPICE model available at www.ti.com
1
2
3
4
5
6
7
14
13
12
11
10
9
8
Out D
InD
+In D
V
+In C
InC
Out C
Out A
In A
+In A
V+
+In B
In B
Out B
OPA4350
SO−14
AD
BC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
Out D
In D
+In D
V
+In C
In C
Out C
NC
Out A
In A
+In A
+V
+In B
In B
Out B
NC
OPA4350
SSOP−16
AD
BC
1
2
3
4
8
7
6
5
NC
V+
Output
NC
NC
In
+In
V
OPA350
DIP−8, SO8, MSOP−8
1
2
3
4
8
7
6
5
V+
Out B
In B
+In B
Out A
In A
+In A
OPA2350
DIP−8, SO8, MSOP−8
A
B
All trademarks are the property of their respective owners.
OPA350
OPA2350
OPA4350
High-Speed, Single-Supply, Rail-to-Rail
OPERATIONAL AMPLIFIERS
MicroAmplifiertSeries
SBOS099CSEPTEMBER 2000 − REVISED JANUARY 2005
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          
 !     !   
www.ti.com
Copyright 2000−2005, Texas Instruments Incorporated
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
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2
ABSOLUTE MAXIMUM RATINGS(1)
Supply Voltage 7.0V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Signal Input Terminals(2),Voltage (V−) − 0.3V to (V+) + 0.3V. . . . .
Current 10mA. . . . . . . . . . . . . . . . . . . . . .
Open Short-Circuit Current(3) Continuous. . . . . . . . . . . . . . . . . . . .
Operating Temperature Range −55 °C to +150°C. . . . . . . . . . . . . . .
Storage Temperature Range −55 °C to +150°C. . . . . . . . . . . . . . . . .
Junction Temperature +150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Lead Temperature (soldering, 10s) +300°C. . . . . . . . . . . . . . . . . . . . .
(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 , an d
functional operation of the device at these or any other conditions
beyond those specified is not implied.
(2) Input terminals are diode-clamped to the power-supply rails.
Input signals that can swing more than 0.3V beyond the supply
rails should be current limited to 10mA or less.
(3) Short-circuit to ground, one amplifier per package.
ELECTROSTATIC DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Texas
Instruments 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.
PACKAGE/ORDERING INFORMATION (1)
PRODUCT PACKAGE-LEAD PACKAGE
DESIGNATOR
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING ORDERING
NUMBER TRANSPORT
MEDIA, QUANTITY
SINGLE
OPA350EA
MSOP-8
DGK
−40°C to +85°C
C50
OPA350EA/250 Tape and Reel, 250
OPA350EA
MSOP-8
DGK
−40
°
C to +85
°
C
C50
OPA350EA/2K5 Tape and Reel, 2500
OPA350UA
SO-8
D
−40°C to +85°C
OPA350UA
OPA350UA Rails
OPA350UA
SO-8
D
−40
°
C to +85
°
C
OPA350UA
OPA350UA/2K5 Tape and Reel, 2500
OPA350PA DIP-8 P −40°C to +85°C OPA350PA OPA350PA Rails
DUAL
OPA2350EA
MSOP-8
DGK
−40°C to +85°C
D50
OPA2350EA/250 Tape and Reel, 250
OPA2350EA
MSOP-8
DGK
−40
°
C to +85
°
C
D50
OPA2350EA/2K5 Tape and Reel, 2500
OPA2350UA
SO-8
D
−40°C to +85°C
OPA2350UA
OPA2350UA Rails
OPA2350UA
SO-8
D
−40
°
C to +85
°
C
OPA2350UA
OPA2350UA/2K5 Tape and Reel, 2500
OPA2350PA DIP-8 P −40°C to +85°C OPA2350PA OPA2350PA Rails
QUAD
OPA4350EA
SSOP-16
DBQ
−40°C to +85°C
OPA4350EA
OPA4350EA/250 Tape and Reel, 250
OPA4350EA
SSOP-16
DBQ
−40
°
C to +85
°
C
OPA4350EA
OPA4350EA/2K5 Tape and Reel, 2500
OPA4350UA
SO-14
D
−40°C to +85°C
OPA4350UA
OPA4350UA Rails
OPA4350UA
SO-14
D
−40
°
C to +85
°
C
OPA4350UA
OPA4350UA/2K5 Tape and Reel, 2500
(1) For the most current package and ordering information, see the Package Option Addendum located at the end of this data sheet.
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3
ELECTRICAL CHARACTERISTICS: VS = 2.7V to 5.5V
Boldface limits apply over the temperature range, TA = −40°C to +85°C. VS = 5V.
All specifications at TA = +25°C, RL = 1k connected to VS/2 and VOUT = VS/2, unless otherwise noted.
OPA350, OPA2350, OP A4350
PARAMETER TEST CONDITIONS MIN TYP(1) MAX UNIT
OFFSET VOLT AGE
Input Offset Voltage VOS VS = 5V ±150 ±500 µV
TA = −40°C to +85°C±1mV
vs Temperature TA = −40°C to +85°C±4µV/°C
vs Power-Supply Rejection Ratio PSRR VS = 2.7V to 5.5V, VCM = 0V 40 150 µV/V
TA = −40°C to +85°C VS = 2.7V to 5.5V, VCM = 0V 175 µV/V
Channel Separation (dual, quad) dc 0.15 µV/V
INPUT BIAS CURRENT
Input Bias Current IB±0.5 ±10 pA
vs Temperature See Typical Characteristics
Input Offset Current IOS ±0.5 ±10 pA
NOISE
Input Voltage Noise, f = 100Hz to 400kHz 4µVrms
Input Voltage Noise Density , f = 10kHz en7 nV/Hz
Input Current Noise Density, f = 100kHz 5 nV/Hz
Current Noise Density, f = 10kHz in4 fA/Hz
INPUT VOLTAGE RANGE
Common-Mode Voltage Range VCM TA = −40°C to +85°C −0.1 (V+) + 0 . 1 V
Common-Mode Rejection Ratio CMRR VS = 2.7V, −0.1V < VCM < 2.8V 66 84 dB
VS = 5.5V, −0.1V < VCM < 5.6V 74 90 dB
TA = −40°C to +85°C VS = 5.5V, −0.1V < VCM < 5.6V 74 dB
INPUT IMPEDANCE
Differential 1013 || 2.5 || pF
Common-Mode 1013 || 6.5 || pF
OPEN-LOOP GAIN
Open-Loop Voltage Gain AOL RL = 10k, 50mV < VO < (V+) −50mV 100 122 dB
TA = −40°C to +85°C RL = 10kW, 50mV < VO < (V+) −50mV 100 dB
RL = 1k, 200mV < VO < (V+) −200mV 100 120 dB
TA = −40°C to +85°C RL = 1kW, 200mV < VO < (V+) −200mV 100 dB
FREQUENCY RESPONSE CL = 100pF
Gain-Bandwidth Product GBW G = 1 38 MHz
Slew Rate SR G = 1 22 V/µs
Settling Time: 0.1% G = ±1, 2V Step 0.22 µs
0.01% G = ±1, 2V Step 0.5 µs
Overload Recovery Time VIN G = VS0.1 µs
Total Harmonic Distortion + Noise THD+N RL = 600, VO = 2.5VPP(2), G = 1, f = 1kHz 0.0006 %
Differential Gain Error G = 2, RL = 600, VO = 1.4V(3) 0.17 %
Differential Phase Error G = 2, RL = 600, VO = 1.4V(3) 0.17 deg
(1) VS = +5V.
(2) VOUT = 0.25V to 2.75V.
(3) NTSC signal generator used. See Figure 6 for test circuit.
(4) Output voltage swings are measured between the output and power supply rails.
(5) See typical characteristic curve, Output Voltage Swing vs Output Current.
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4
ELECTRICAL CHARACTERISTICS: VS = 2.7V to 5.5V (continued)
Boldface limits apply over the temperature range, TA = −40°C to +85°C. VS = 5V.
All specifications at TA = +25°C, RL = 1k connected to VS/2 and VOUT = VS/2, unless otherwise noted.
OPA350, OPA2350, OP A4350
PARAMETER UNITMAXTYP(1)
MINTEST CONDITIONS
OUTPUT
Voltage Output Swing from Rail(4) VOUT RL = 10k, AOL 100dB 10 50 mV
TA = −40°C to +85°C RL = 10kW, AOL 100dB 50 mV
RL = 1k, AOL 100dB 25 200 mV
TA = −40°C to +85°C RL = 1kW, AOL 100dB 200 mV
Output Current IOUT ±40(5) mA
Short-Circuit Current ISC ±80 mA
Capacitive Load Drive CLOAD See Typical Characteristics
POWER SUPPLY
Operating Voltage Range VSTA = −40°C to +85°C 2.7 5.5 V
Minimum Operating Voltage 2.5 V
Quiescent Current (per amplifier) IQIO = 0 5.2 7.5 mA
TA = −40°C to +85°CIO = 0 8.5 mA
TEMPERATURE RANGE
Specified Range −40 +85 °C
Operating Range −55 +150 °C
Storage Range −55 +150 °C
Thermal Resistance qJA
MSOP-8 Surface Mount 150 °C/W
SO-8 Surface Mount 150 °C/W
DIP-8 100 °C/W
SO-14 Surface Mount 100 °C/W
SSOP-16 Surface Mount 100 °C/W
(1) VS = +5V.
(2) VOUT = 0.25V to 2.75V.
(3) NTSC signal generator used. See Figure 6 for test circuit.
(4) Output voltage swings are measured between the output and power supply rails.
(5) See typical characteristic curve, Output Voltage Swing vs Output Current.
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5
TYPICAL CHARACTERISTICS
All specifications at TA = +25°C, VS = +5V, and RL = 1kconnected to VS/2, unless otherwise noted.
0.1 1
160
140
120
100
80
60
40
20
0
0
45
90
135
180
Phase (_)
Frequency (Hz)
10 100 1k 10k 100k 1M 10M 100M
G
φ
OPEN-LOOP GAIN/PHASE vs FREQUENCY
Voltage Gain (dB)
INPUT VOLTAGE AND CURRENT NOISE
SPECTRAL DENSITY vs FREQUENCY
100k
10k
1k
100
10
1
10k
1k
100
10
1
0.1
Voltage Noise (nVHz)
Frequency (Hz)
10 100 1k 10k 100k 1M 10M
Current Noise (fAHz)
Voltage Noise
Current Noise
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
1
0.1
0.01
0.001
0.0001
THD+N (%)
Frequency (Hz)
10 100 1k 10k 100k
RL= 600
G = 100, 3VPP (VO=1Vto4V)
G=10,3V
PP (VO=1Vto4V)
G = 1, 3VPP (VO=1Vto4V)
Input goes through transition region
G = 1, 2.5VPP (VO= 0.25V to 2.75V)
Input does NOT go through transition region
POWER SUPPLY AND COMMON−MODE
REJECTION RATIO vs FREQUENCY
100
90
80
70
60
50
40
30
20
10
0
PSRR, CMRR (dB)
Frequency (Hz)
10 100 1k 10k 100k 1M 10M
PSRR
CMRR
(VS=+5V
VCM =0.1V to 5.1V)
CHANNEL SEPARATION vs FREQUENCY
Frequency (Hz)
Channel Separation (dB)
140
130
120
110
100
90
80
70
60 10010 1k 1M100k10k 10M
Dual and quad devices.
HARMONIC DISTORTION + NOISE vs FREQUENCY
1
(40dBc)
0.1
(60dBc)
0.01
(80dBc)
0.001
(100dBc)
0.0001
(120dBc)
Harmonic Distortion (%)
Frequency (Hz)
1k 10k 100k 1M
G=1
VO=2.5V
PP
RL= 600
3rd−Harmonic 2nd−Harmonic
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6
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, VS = +5V, and RL = 1kconnected to VS/2, unless otherwise noted.
DIFFERENTIAL GAIN/PHASE vs RESISTIVE LOAD
0.5
0.4
0.3
0.2
0.1
0
Differential Gain (%)
Differential Phase (_)
Resistive Load ()
0 100 200 300 500400 600 800700 900 100
0
G=2
VO=1.4V
NTSC Signal Generator
SeeFigure6fortestcircuit.
Phase
Gain
COMMONMODE AND POWER−SUPPLY REJECTION RATIO
vs TEMPERATURE
100
90
80
70
60
CMRR (dB)
110
100
90
80
70
PSRR (dB)
Temperature (_C)
75 50 25 0 25 50 75 100 125
CMRR, VS=5.5V
(VCM =0.1V to +5.6V)
CMRR, VS=2.7V
(VCM =0.1V to+2.8V)
PSRR
QUIESCENT CURRENT AND
SHORT−CIRCUIT CURRENT vs TEMPERATURE
Temperature (_C)
Quiescent Current (mA)
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
100
90
80
70
60
50
40
30
Short−Circuit Current (mA)
75 50 25 0 25 50 75 100 125
IQ
+ISC
ISC
OPEN−LOOP GAIN vs TEMPERATURE
130
125
120
115
110
Open−Loop Gain (dB)
Temperature (_C)
75 50 250255075100125
RL=600
RL=1k
RL=10k
SLEW RATE vs TEMPERATURE
Temperature (_C)
Slew Rate (V/µs)
40
35
30
25
20
15
10
5
0
75 50 250 255075100125
Negative Slew Rate
Positive Slew Rate
QUIESCENT CURRENT vs SUPPLY VOLTAGE
Supply Voltage (V)
Quiescent Current (mA)
6.0
5.5
5.0
4.5
4.0
3.5
3.02.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
Per Amplifier
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7
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, VS = +5V, and RL = 1kconnected to VS/2, unless otherwise noted.
INPUT BIAS CURRENT vs TEMPERATURE
Input Bias Current (pA)
Temperature (_C)
75 50 25 0 25 50 75 100 125
1k
100
10
1
0.1
CLOSED−LOOP OUTPUT IMPEDANCE vs FREQUENCY
Frequency (Hz)
Output Impedance ()
100
10
1
0.1
0.01
0.001
0.0001 1 10 100 1k 10k 100k 1M 10M 100
M
G = 100
G=10
G=1
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
Output Current (mA)
Output Voltage (V)
V+
(V+)1
(V+)2
(V)+2
(V)+1
(V)0±10 ±20 ±30 ±4
0
+25_C
+125_C55_C
55_C
+125_C+25_C
Depending on circuit configuration
(including closed−loop gain) performance
may be degraded in shaded region.
INPUT BIAS CURRENT
vs INPUT COMMON−MODE VOLTAGE
CommonMode Voltage (V)
Input Bias Current (pA)
1.5
1.0
0.5
0.0
0.5
0.5 0.0 0.5 1.0 2.01.5 2.5 3.0 3.5 4.0 5.04.5 5.5
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
100M1M 10M
Frequency (Hz)
100k
6
5
4
3
2
1
0
Output Voltage (VPP)
Maximum output
voltage without
slew rate−induced
distortion.
VS=2.7V
VS=5.5V
OPEN−LOOP GAIN vs OUTPUT VOLTAGE SWING
140
130
120
110
100
90
80
70
60
Open−Loop Gain (dB)
Output Voltage Swing from Rails (mV)
0204060 10080 120 160140 180 200
IOUT =4.2mA
IOUT =250
µAIOUT =2.5mA
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8
TYPICAL CHARACTERISTICS (continued)
All specifications at TA = +25°C, VS = +5V, and RL = 1kconnected to VS/2, unless otherwise noted.
Offset Voltage (µV)
OFFSET VOLTAGE
PRODUCTION DISTRIBUTION
18
16
14
12
10
8
6
4
2
0
Percent of Amplifiers (%)
500
450
400
350
300
250
200
150
100
50
0
50
100
150
200
250
300
350
400
450
500
Typical distribution of
packaged units.
SMALLSIGNAL OVERSHOOT vs LOAD CAPACITANCE
1M100 1k 10k 100k
Load Capacitance (pF)
10
80
70
60
50
40
30
20
10
0
Overshoot (%)
G=1
G=1
G=±10
SMALL−SIGNAL STEP RESPONSE
CL= 100pF
100ns/div
50mV/div
Offset Voltage Drift (µV/_C)
OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
20
18
16
14
12
10
8
6
4
2
00123456789101112131415
Percent of Amplifiers (%)
Typical production
distribution of
packaged units.
SETTLING TIME vs CLOSED−LOOP GAIN
10
1
0.1
Settling Time (µs)
Closed−Loop Gain (V/V)
110 100
0.1%
0.01%
LARGE−SIGNAL STEP RESPONSE
CL= 100pF
200ns/div
1V/div
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APPLICATIONS INFORMATION
OPA350 series op amps are fabricated on a
state-of-the-art 0.6 micron CMOS process. They are
unity-gain stable and suitable for a wide range of
general-purpose applications. Rail-to-rail input/output
make them ideal for driving sampling A/D converters.
They are also well-suited for controlling the output
power in cell phones. These applications often require
high speed and low noise. In addition, the OPA350
series offers a low-cost solution for general-purpose
and consumer video applications (75 drive capability).
Excellent ac performance makes the OPA350 series
well-suited for audio applications. Their bandwidth,
slew rate, low noise (5nV/Hz), low THD (0.0006%),
and small package options are ideal for these
applications. The class AB output stage is capable of
driving 6 0 0 loads connected to any point between V+
and ground.
Rail-to-rail input and output swing significantly
increases dynamic range, especially in low voltage
supply applications. Figure 1 shows the input and
output waveforms for the OPA350 in unity-gain
configuration. Operation is from a single +5V supply
with a 1k load connected to VS/2. The input is a 5VPP
sinusoid. Output voltage swing is approximately
4.95VPP.
Power supply pins should be bypassed with 0.01µF
ceramic capacitors.
VS=+5,G=+1,R
L=1k
5V
VIN
0
5V
VOUT
0
1.25V/div
Figure 1. Rail-to-Rail Input and Output
OPERATING VOLTAGE
OPA350 series op amps are fully specified from +2.7V
to +5.5V. However, supply voltage may range from
+2.5V to +5.5V. Parameters are tested over the
specified supply range—a unique feature of the
OPA350 series. In addition, many specifications apply
from −40°C to +85°C. Most behavior remains virtually
unchanged throughout the full operating voltage range.
Parameters that vary significantly with operating
voltage or temperature are shown in the typical
characteristics.
RAIL-TO-RAIL INPUT
The tested input common-mode voltage range of the
OPA350 series extends 100mV 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, as shown in Figure 2. The
N-channel pair is active for input voltages close to the
positive rail, typically (V+) – 1.8V to 100mV above the
positive supply, while the P-channel pair is on for inputs
from 100mV below the negative supply to
approximately (V+) 1.8V. There is a small transition
region, typically (V+) – 2V to (V+) – 1.6V, in which both
pairs are on. This 400mV transition region can vary
±400mV with process variation. Thus, the transition
region (both input stages on) can range from (V+) –
2.4V to (V+) 2.0V on the low end, up to (V+) – 1.6V
to (V+) – 1.2V on the high end.
OPA350 series op amps are laser-trimmed to reduce
offset voltage difference between the N-channel and
P-channel input stages, resulting in improved
common-mode rejection and a smooth transition
between the N-channel pair and the P-channel pair.
However, within the 400mV transition region PSRR,
CMRR, offset voltage, offset drift, and THD may be
degraded compared to operation outside this region.
A double-folded cascode adds the signal from the two
input pairs and presents a differential signal to the class
AB output stage. Normally, input bias current is
approximately 500fA. However, large inputs (greater
than 300mV beyond the supply rails) can turn on the
OPA350’s input protection diodes, causing excessive
current to flow in or out of the input pins. Momentary
voltages greater than 300mV beyond the power supply
can be tolerated if the current on the input pins is limited
to 10mA. This is easily accomplished with an input
resistor, as shown in Figure 3. Many input signals are
inherently current-limited to less than 10mA; therefore,
a limiting resistor is not required.
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10
VBIAS1
VBIAS2
VIN+VIN
Class AB
Control
Circuitry VO
V
(Ground)
V+
Reference
Current
Figure 2. Simplified Schematic
5k
OPAx350
10mA max
V+
VIN
VOUT
IOVERLOAD
Figure 3. Input Current Protection for Voltages
Exceeding the Supply Voltage
RAIL-TO-RAIL OUTPUT
A class AB output stage with common-source
transistors is used to achieve rail-to-rail output. For light
resistive loads (>10k), the output voltage swing is
typically ten m i l l i v o l t s f r o m the supply rails. With heavier
resistive loads (600 to 10k), the output can swing to
within a few tens of millivolts from the supply rails and
maintain high open-loop gain. See the typical
characteristics Output V oltage Swing vs Output Current
and Open-Loop Gain vs Output Voltage.
CAPACITIVE LOAD AND STABILITY
OPA350 series op amps can drive a wide range of
capacitive loads. However, all op amps under certain
conditions may become unstable. Op amp
configuration, gain, and load value are just a few of the
factors to consider when determining stability. An op
amp in unity-gain configuration is the most susceptible
to the effects of capacitive load. The capacitive load
reacts with the op amp’s output impedance, along with
any additional load resistance, to create a pole in the
small-signal response that degrades the phase margin.
In unity gain, OPA350 series op amps perform well with
very large capacitive loads. Increasing gain enhances
the amplifier’s ability to drive more capacitance. The
typical characteristic Small-Signal Overshoot vs
Capacitive Load shows performance with a 1k
resistive load. Increasing load resistance improves
capacitive load drive capability.
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11
FEEDBACK CAPACITOR IMPROVES
RESPONSE
For optimum settling time and stability with
high-impedance feedback networks, it may be
necessary to add a feedback capacitor across the
feedback resistor, RF, as shown in Figure 4. This
capacitor compensates for the zero created by the
feedback network impedance and the OPA350’s input
capacitance (and any parasitic layout capacitance).
The effect becomes more significant with higher
impedance networks.
OPA350
V+
VOUT
VIN
RIN
RIN CIN =R
FCF
RF
CL
CIN
CIN
CF
Where CIN is equal to the OPA350’s input
capacitance (approximately 9pF) plus any
parasitic layout capacitance.
Figure 4. Feedback Capacitor Improves Dynamic
Performance
It is suggested that a variable capacitor be used for the
feedback capacitor since input capacitance may vary
between op amps and layout capacitance is difficult to
determine. For the circuit shown in Figure 4, the value
of the variable feedback capacitor should be chosen so
that the input resistance times the input capacitance of
the OPA350 (typically 9pF) plus the estimated parasitic
layout capacitance equals the feedback capacitor times
the feedback resistor:
RIN @CIN +RF@CF
where CIN is equal to the OPA350’s input capacitance
(sum of differential and common-mode) plus the layout
capacitance. The capacitor can be varied until optimum
performance is obtained.
DRIVING A/D CONVERTERS
OPA350 series op amps are optimized for driving
medium speed (up to 500kHz) sampling A/D
converters. However, they also offer excellent
performance for higher speed converters. The OPA350
series provides an effective means of buffering the
A/D’s input capacitance and resulting charge injection
while providing signal gain.
Figure 5 shows the OPA350 driving an ADS7861. The
ADS7861 is a dual, 500kHz, 12-bit sampling converter
in the tiny SSOP-24 package. When used with the
miniature package options of the OPA350 series, the
combination is ideal for space-limited applications. For
further information, consult the ADS7861 data sheet
(SBAS110A).
OUTPUT IMPEDANCE
The low frequency open-loop output impedance of the
OPA350’s common-source output stage is
approximately 1 k . When the op amp is connected with
feedback, this value is reduced significantly by the loop
gain of the op amp. For example, with 122dB of
open-loop gain, the output impedance is reduced in
unity-gain to less than 0.001. For each decade rise in
the closed-loop gain, the loop gain is reduced by the
same amount which results in a ten-fold increase in
effective output impedance (see the typical
characteristic, Output Impedance vs Frequency).
At higher frequencies, the output impedance will rise as
the open-loop gain of the op amp drops. However, at
these frequencies the output also becomes capacitive
due to parasitic capacitance. This prevents the output
impedance from becoming too high, which can cause
stability problems when driving capacitive loads. As
mentioned previously, the OPA350 has excellent
capacitive load drive capability for an op amp with its
bandwidth.
VIDEO LINE DRIVER
Figure 6 shows a circuit for a single supply, G = 2
composite video line driver. The synchronized outputs
of a composite video line driver extend below ground.
As shown, the input to the op amp should be ac-coupled
and shifted positively to provide adequate signal swing
to account for these negative signals in a single-supply
configuration.
The input is terminated with a 75 resistor and
ac-coupled with a 47µF capacitor to a voltage divider
that provides the dc bias point to the input. In Figure 6,
this point is approximately (V−) + 1.7V. Setting the
optimal bias point requires some understanding of the
nature of composite video signals. For best
performance, one should be careful to avoid the
distortion caused by the transition region of the
OPA350’s complementary input stage. Refer to the
discussion of rail-to-rail input.
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SBOS099CSEPTEMBER 2000 − REVISED JANUARY 2005
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12
1/4
OPA4350
VIN B1
2
3
4
2k
2k
CB1
CH B1+
CH B1
CH B0+
CH B0
CH A1+
CH A1
CH A0+
CH A0
REFIN
REFOUT
SERIAL DATA A
SERIAL DATA B
BUSY
CLOCK
CS
RD
CONVST
A0
M0
M1
2
3
4
5
6
7
8
9
10
11
23
22
21
20
19
18
17
16
15
14
1/4
OPA4350
VIN B0
+5V
6
5
2k
2k
CB0
1/4
OPA4350
VIN A1
9
10
12
13
8
7
1
2k
2k
CA1
1/4
OPA4350
VIN A0
14
11
112
2k
2k
CA0
0.1µF0.1
µF
+VA
+VD
24 13
Serial
Interface
DGND AGND
ADS7861
VIN = 0V to 2.45V for 0V to 4.9V output.
Choose CB1,C
B0,C
A1,C
A0 to filter high frequency noise.
Figure 5. OPA4350 Driving Sampling A/D Converter
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SBOS099CSEPTEMBER 2000 − REVISED JANUARY 2005
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13
OPA350
+5V
VOUT
+5V (pin 7)
Video
In
ROUT
RL
Cable
RF
1k
RG
1k
R4
5k
R3
5k
C3
10µF
0.1µF10µF
+
6
7
4
3
2
C4
0.1µF
C5
1000µF
C2
47µF
R2
5k
R1
75
C1
220µF
Figure 6. Single-Supply Video Line Driver
1/2
OPA2350
1/2
OPA2350
R3
25k
R2
25k
RG
R1
100k
R4
100k
RL
10k
VO
50k
G=5+200k
RG
+5V
+5V
REF1004−2.5
4
8
(2.5V)
Figure 7. Two Op-Amp Instrumentation Amplifier With
Improved High Frequency Common-Mode Rejection
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SBOS099CSEPTEMBER 2000 − REVISED JANUARY 2005
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14
+2.5V
VIN
R2
19.6k
R1
2.74k
2.5V
C2
1nF
RL
20k
OPA350 VOUT
C1
4.7nF
Figure 8. 10kHz Low-Pass Filter
+2.5V
VIN
C2
270pF
C1
1830pF
2.5V
R2
49.9k
RL
20k
OPA350 VOUT
R1
10.5k
Figure 9. 10kHz High-Pass Filter
PACKAGE OPTION ADDENDUM
www.ti.com 11-Apr-2013
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead/Ball Finish MSL Peak Temp
(3)
Op Temp (°C) Top-Side Markings
(4)
Samples
OPA2350EA/250 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 D50
OPA2350EA/250G4 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 D50
OPA2350EA/2K5 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 D50
OPA2350EA/2K5G4 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 D50
OPA2350PA ACTIVE PDIP P 8 50 Green (RoHS
& no Sb/Br) CU NIPDAU N / A for Pkg Type -40 to 85 OPA2350PA
OPA2350PAG4 ACTIVE PDIP P 8 50 Green (RoHS
& no Sb/Br) CU NIPDAU N / A for Pkg Type -40 to 85 OPA2350PA
OPA2350UA ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
2350UA
OPA2350UA/2K5 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
2350UA
OPA2350UA/2K5G4 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
2350UA
OPA2350UAG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
2350UA
OPA350EA/250 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 C50
OPA350EA/250G4 ACTIVE VSSOP DGK 8 250 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 C50
OPA350EA/2K5 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 C50
OPA350EA/2K5G4 ACTIVE VSSOP DGK 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAUAG Level-2-260C-1 YEAR -40 to 85 C50
OPA350PA ACTIVE PDIP P 8 50 Green (RoHS
& no Sb/Br) CU NIPDAU N / A for Pkg Type -40 to 85 OPA350PA
OPA350PAG4 ACTIVE PDIP P 8 50 Green (RoHS
& no Sb/Br) CU NIPDAU N / A for Pkg Type -40 to 85 OPA350PA
OPA350UA ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
350UA
PACKAGE OPTION ADDENDUM
www.ti.com 11-Apr-2013
Addendum-Page 2
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead/Ball Finish MSL Peak Temp
(3)
Op Temp (°C) Top-Side Markings
(4)
Samples
OPA350UA/2K5 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
350UA
OPA350UA/2K5G4 ACTIVE SOIC D 8 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
350UA
OPA350UAG4 ACTIVE SOIC D 8 75 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
350UA
OPA4350EA/250 ACTIVE SSOP DBQ 16 250 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR OPA
4350EA
OPA4350EA/250G4 ACTIVE SSOP DBQ 16 250 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR OPA
4350EA
OPA4350EA/2K5 ACTIVE SSOP DBQ 16 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
4350EA
OPA4350EA/2K5G4 ACTIVE SSOP DBQ 16 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR -40 to 85 OPA
4350EA
OPA4350UA ACTIVE SOIC D 14 50 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR OPA4350UA
OPA4350UA/2K5 ACTIVE SOIC D 14 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR OPA4350UA
OPA4350UA/2K5G4 ACTIVE SOIC D 14 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR OPA4350UA
OPA4350UAG4 ACTIVE SOIC D 14 50 Green (RoHS
& no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR OPA4350UA
(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.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
PACKAGE OPTION ADDENDUM
www.ti.com 11-Apr-2013
Addendum-Page 3
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) Multiple Top-Side Markings will be inside parentheses. Only one Top-Side Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a
continuation of the previous line and the two combined represent the entire Top-Side Marking for that device.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.