OPA
4727
OPA
2727
OP
A7
27
OP
A7
28
OP
A2
727
OP
A7
27
OP
A7
28
OPA727, OPA2727
OPA4727, OPA728
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
e-trim™ 20MHz, High Precision CMOS
Operational Amplifier
FEATURES
•
•
•
•
•
•
•
•
•
•
DESCRIPTION
OFFSET: 15µV (typ), 150µV (max)
DRIFT: 0.3µV/°C (typ), 1.5µV/°C (max)
BANDWIDTH: 20MHz
SLEW RATE: 30V/µs
BIAS CURRENT: 500pA (max)
LOW NOISE: 6nV/√Hz at 100kHz
THD+N: 0.0003% at 1kHz
QUIESCENT CURRENT: 4.3mA/ch
SUPPLY VOLTAGE: 4V to 12V
SHUTDOWN MODE (OPA728): 6µA
APPLICATIONS
•
•
•
•
•
•
•
•
•
OPTICAL NETWORKING
TRANSIMPEDANCE AMPLIFIERS
INTEGRATORS
ACTIVE FILTERS
A/D CONVERTER DRIVERS
I/V CONVERTER FOR DACs
HIGH PERFORMANCE AUDIO
PROCESS CONTROL
TEST EQUIPMENT
OPAx727 AND OPAx728 RELATED PRODUCTS
FEATURES
PRODUCT
20MHz, 3mV, 4µV/°C
(non-e-trim version of OPA727)
OPA725
20MHz, 3mV, 4µV/°C, Shutdown
(non-e-trim version of OPA728)
OPA726
+12V
OPA727
l
VOUT
The OPA727 and OPA728 series op amps use a
state-of-the-art 12V analog CMOS process and
e-trim, a package-level trim, offering outstanding dc
precision and ac performance. The extremely low
offset (150µV max) and drift (1.5µV/°C) are achieved
by trimming the IC digitally after packaging to avoid
the shift in parameters as a result of stresses during
package assembly. To correct for offset drift, the
OPA727 and OPA728 family is trimmed over
temperature. The devices feature very high CMRR
and open-loop gain to minimize errors.
Excellent ac characteristics, such as 20MHz GBW,
30V/µs slew rate and 0.0003% THD+N make the
OPA727 and OPA728 well-suited for communication,
high-end audio, and active filter applications. With a
bias current of less than 500pA, they are well suited
for use as transimpedance (I/V-conversion)
amplifiers for monitoring optical power in ONET
applications.
Optimized for single-supply operation up to 12V, the
input common-mode range extends to GND for true
single-supply functionality. The output swings to
within 150mV of the rails, maximizing dynamic range.
The low quiescent current of 4.3mA makes it
well-suited for use in battery-operated equipment.
The OPA728 shutdown version reduces the
quiescent current to typically 6µA and features a
reference pin for easy shutdown operation with
standard CMOS logic in dual-supply applications.
For ease of use, the OPA727 and OPA728 op amp
families are fully specified and tested over the supply
range of 4V to 12V. The OPA727 (single) and
OPA728 (single with shutdown) are available in
MSOP-8 and DFN-8; the OPA2727 (dual) is
available in DFN-8 and SO-8; and the quad version
OPA4727 in TSSOP-14. All versions are specified for
operation from –40°C to +125°C.
-VB
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.
e-trim is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2007, Texas Instruments Incorporated
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
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
PACKAGE MARKING
MSOP-8
DGK
AUE
DFN-8
DRB
NSF
DFN-8
DRB
NSD
SO-8
D
O2727A
TSSOP-14
PW
OPA4727
MSOP-8
DGK
AUF
DFN-8
DRB
NSG
Non-Shutdown
OPA727
OPA2727
OPA4727
Shutdown
OPA728
(1)
For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
ABSOLUTE MAXIMUM RATINGS (1)
Supply Voltage
Signal Input Terminals
UNIT
+13.2
V
Voltage (2)
–0.5 to (V+) + 0.5
V
Current (2)
±10
mA
Output Short-Circuit (3)
Continuous
Operating Temperature
–55 to +125
°C
Storage Temperature
–55 to +150
°C
Junction Temperature
+150
°C
Human Body Model
2000
V
Charged Device Model
1000
V
ESD Rating
(1)
(2)
(3)
2
OPA727, OPA2727
OPA4727, OPA728
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, and functional operation of the device at these or any other conditions beyond
those specified is not supported.
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.
Short-circuit to ground, one amplifier per package.
Submit Documentation Feedback
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
PIN CONFIGURATIONS
OPA727
MSOP-8
(TOP VIEW)
(1)
OPA2727
SO-8
(TOP VIEW)
(1)
1
8
NC
-IN
2
7
V+
+IN
3
6
OUT
NC
V-
4
NC
5
OUT A
1
-IN A
2
+IN A
3
V-
4
(1)
-IN 2
+IN 3
Exposed
Thermal
Die Pad
on
(2)
Underside
(3)
1
2
-IN
-IN A 2
6 OUT
+IN A 3
(1)
8
Enable
7
V+
3
6
V-
4
5
NC
OUT A
V- 4
+IN B
7 OUT B
6 -IN B
5 +IN B
14 OUT D
1
A
D
13 -IN D
-IN A
2
+IN A
3
12 +IN D
V+
4
11 V-
+IN B
5
10 +IN C
-IN B
6
OUT B
7
B
C
9
-IN C
8
OUT C
8 Enable
1
+IN 3
5
(1)
OPA728
DFN-8
(TOP VIEW)
-IN 2
-IN B
OPA4727
TSSOP-14
(TOP VIEW)
+IN
(3)
Exposed
Thermal
Die Pad
on
(2)
Underside
V- 4
OUT
REF
6
8 V+
OUT A 1
OPA728
MSOP-8
(TOP VIEW)
REF
OUT B
(1)
7 V+
5 NC
V- 4
7
OPA2727
DFN-8
(TOP VIEW)
8 NC
1
B
V+
(1)
OPA727
DFN-8
(TOP VIEW)
NC
A
8
Exposed
Thermal
Die Pad
on
Underside(2)
7 V+
6 OUT
5 NC
(1)
Notes:
1. NC denotes no internal connection.
2. Connect thermal die pad to V–.
3. REF is the reference voltage for ENABLE pin.
Submit Documentation Feedback
3
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
ELECTRICAL CHARACTERISTICS: VS = +4V to +12V or VS = ±2V to ±6V
Boldface limits apply over the specified temperature range, TA = –40°C to +125°C.
At TA = +25°C, RL = 10kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.
OPA727, OPA728,
OPA2727, OPA4727
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
OPA727 DFN, OPA728 DFN Packages
15
150
µV
OPA727 MSOP, OPA728 MSOP Packages
15
300
µV
OPA2727
15
150
µV
OPA4727
15
175
µV
0°C to +85°C
0.3
1.5
µV/°C
–40°C to +125°C
0.6
3
µV/°C
VS = ±2V to ±6V, VCM = V–
30
150
µV/V
150
µV/V
OFFSET VOLTAGE
Input Offset Voltage
Drift
VOS
dVOS/dT
vs Power Supply
PSRR
VS = ±5V, VCM = 0V
VS = ±2V to ±6V, VCM = V–
Over Temperature
Channel Separation, dc
µV/V
1
INPUT BIAS CURRENT
±85
Input Bias Current
Over Temperature
Input Ofset Current
±500
pA
See Typical Characteristics
±10
IOS
±100
pA
NOISE
Input Voltage Noise, f = 0.1Hz to 10Hz
en
VS = ±6V, VCM = 0V
10
µVPP
Input Voltage Noise Density, f = 10kHz
en
VS = ±6V, VCM = 0V
10
nV/√Hz
Input Voltage Noise Density, f = 100kHz
en
VS = ±6V, VCM = 0V
6
nV/√Hz
in
VS = ±6V, VCM = 0V
2.5
fA/√Hz
Input Current Noise Density, f = 1kHz
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
VCM
Common-Mode Rejection Ratio
CMRR
Over Temperature
Over Temperature
(V–)
(V–) ≤ VCM ≤ (V+) – 2.5V
86
(V–) ≤ VCM ≤ (V+) – 2.5V
84
(V–) ≤ VCM ≤ (V+) – 3V
94
(V–) ≤ VCM ≤ (V+) – 3V
84
(V+)–2.5
94
V
dB
dB
100
dB
dB
INPUT IMPEDANCE
Differential
1011 || 5
Ω || pF
Common-Mode
1011 || 4
Ω || pF
120
dB
OPEN-LOOP GAIN
Open-Loop Voltage Gain
AOL
Over Temperature
RL = 100kΩ, 0.15V < VO < (V+)
–0.15V
110
RL = 100kΩ, 0.15V < VO < (V+)
–0.15V
100
RL = 1kΩ, 0.25V < VO < (V+) –0.25V
106
Over Temperature, OPA727, OPA728
RL = 1kΩ, 0.25V < VO < (V+) –0.25V
96
dB
Over Temperature, OPA2727, OPA4727
RL = 1kΩ, 0.35V < VO < (V+) –0.35V
96
dB
FREQUENCY RESPONSE
Gain-Bandwidth Product
Slew Rate
Settling Time,
GBW
ts
0.01%
Overload Recovery Time
Total Harmonic Distortion + Noise
116
dB
CL = 20 pF
SR
Settling Time, 0.1%
THD+N
20
MHz
G = +1
30
V/µs
VS = ±6V, 5V Step, G = +1
350
ns
VS = ±6V, 5V Step, G = +1
450
ns
VIN × Gain > VS
50
ns
VS = ±6V, VOUT = 2VRMS, RL = 600Ω,
0.003
%
G = +1, f = 1kHz
4
dB
Submit Documentation Feedback
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
ELECTRICAL CHARACTERISTICS: VS = +4V to +12V or VS = ±2V to ±6V (continued)
Boldface limits apply over the specified temperature range, TA = –40°C to +125°C.
At TA = +25°C, RL = 10kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.
OPA727, OPA728,
OPA2727, OPA4727
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
100
150
mV
150
mV
OUTPUT
Voltage Output Swing from Rail
RL = 100kΩ, AOL > 110dB
Over Temperature
RL = 100kΩ, AOL > 100dB
RL = 1kΩ, AOL > 106dB
Over Temperature, OPA727, OPA728
Over Temperature, OPA2727, OPA4727
Output Current
Short-Circuit Current
Capacitive Load Drive
200
RL = 1kΩ, AOL > 96dB
RL = 1kΩ, AOL > 96dB
IOUT
|VS – VOUT| < 1V
ISC
CLOAD
250
mV
250
mV
350
mV
40
mA
±55
mA
See Typical Characteristics
40
Ω
tOFF
5
µs
tON
80
µs
Open-Loop Output Impedance
f = 1MHz, IO = 0
ENABLE/SHUTDOWN (OPA728)
Enable Reference (Ref Pin) Voltage Range
V–
VL (amplifier is disabled)
VH (amplifier is enabled)
(V+) –2
V
< VDGND+0.8V
V
> VDGND+2V
Input Bias Current of Enable Pin
V
5
IQSD
Amplifier Disabled
6
pA
15
µA
12
V
POWER SUPPLY
Specified Voltage Range
Operating Voltage Range
Quiescent Current (per amplifier)
VS
4
VS
3.5 to
13.2
IQ
4.3
Over Temperature
V
6.5
mA
6.5
mA
TEMPERATURE RANGE
Specified Range
–40
+125
°C
Operating Range
–55
+125
°C
Storage Range
–55
+150
°C
Thermal Resistance
θJA
MSOP-8, SO-8
150
°C/W
TSSOP-14
100
°C/W
DFN-8
46
°C/W
Submit Documentation Feedback
5
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
TYPICAL CHARACTERISTICS
At TA = +25°C, VS = ±6V, RL = 10kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.
GAIN AND PHASE vs FREQUENCY
COMMON-MODE REJECTION RATIO vs FREQUENCY
180
180
160
160
140
140
100
100
80
80
60
60
40
40
Gain
20
20
0
0
–20
10
100
1k
10k
100k
1M
10M
CMRR (dB)
Phase
100
Phase (°)
120
120
Gain (dB)
120
80
60
40
20
–20
100M
(V–) £ VCM £ (V+) – 2V
0
10
Frequency (Hz)
100
1k
10k
100k
1M
10M
Frequency (Hz)
Figure 1.
Figure 2.
POWER-SUPPLY REJECTION RATIO vs FREQUENCY
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
7
100
VS = ±6V
90
6
80
5
Amplitude (V)
PSRR (dB)
70
60
50
40
30
4
3
Indicates maximum output
for no visible distortion.
2
20
1
10
0
10k
0
100
1k
10k
100k
1M
10M
100M
100k
Frequency (Hz)
Figure 3.
Figure 4.
CHANNEL SEPARATION vs FREQUENCY
INPUT VOLTAGE NOISE SPECTRAL DENSITY
vs FREQUENCY
140
1000
120
Voltage Noise (nV/ÖHz)
Channel Separation (dB)
10M
1M
Frequency (Hz)
100
80
60
100
10
40
20
1
1k
10k
100k
1M
10M
100M
10
Frequency (Hz)
1k
10k
Frequency (Hz)
Figure 5.
6
100
Figure 6.
Submit Documentation Feedback
100k
1M
10M
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, VS = ±6V, RL = 10kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.
INPUT BIAS CURRENT
vs COMMON-MODE VOLTAGE
100k
OFFSET CURRENT vs TEMPERATURE
+125°C
10k
+85 ° C
1k
1k
+25°C
100
100
IOS(pA)
Input Bias Current (pA)
10k
10
IB < ± 10pA
–10
10
+25°C
1
+85°C
0.1
–100
–1k
–10k
+125°C
0.01
–50
–100k
–6
–4
–2
0
4
2
6
–25
0
25
75
50
100
125
150
Temperature (°C)
Common-- Mode Voltage (V)
Figure 7.
Figure 8.
OPEN-LOOP GAIN vs TEMPERATURE
POWER-SUPPLY REJECTION RATIO vs TEMPERATURE
140
120
130
RL = 100kW
PSRR (dB)
AOL(dB)
120
110
RL = 1kW
100
100
80
90
80
60
–50
–25
0
25
50
75
100
125
150
–50
25
50
75
Figure 9.
Figure 10.
COMMON-MODE REJECTION RATIO vs TEMPERATURE
100
4
90
3
80
100
125
150
QUIESCENT CURRENT vs TEMPERATURE
5
IQ(mA)
CMRR (dB)
0
Temperature (°C)
110
2
1
70
60
–25
Temperature (°C)
(V–) £ VCM £ (V+) – 2V
–50
–25
0
25
0
50
75
100
125
150
–50
–25
0
25
50
75
100
125
150
Temperature (°C)
Temperature (°C)
Figure 11.
Figure 12.
Submit Documentation Feedback
7
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, VS = ±6V, RL = 10kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.
SHORT-CIRCUIT CURRENT vs TEMPERATURE
5.0
90
4.8
80
4.6
70
Short--Circuit (mA)
IQ per Amplifier (mA)
QUIESCENT CURRENT vs SUPPLY VOLTAGE
4.4
4.2
4.0
3.8
3.6
Sourcing
60
50
Sinking
40
30
3.4
20
3.2
10
3.0
0
3
4
5
6
7
8
9
10
11
12
13
–50
14
–25
0
Supply Voltage (V)
25
75
50
100
125
150
Temperature (°C)
Figure 13.
Figure 14.
SHORT-CIRCUIT CURRENT vs SUPPLY VOLTAGE
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
6
90
–40°C
Sourcing
4
70
Output Voltage (V)
Short--Circuit Current (mA)
80
60
Sinking
50
40
30
2
25°C
125°C
0
–2
20
–4
10
–40°C
0
0
13.5
12.5
11.5
10.5
9.5
8.5
7.5
6.5
5.5
4.5
3.5
–6
10
20
30
40
50
60
70
80
Output Current (mA)
Supply Voltage (V)
Figure 15.
Figure 16.
TOTAL HARMONIC DISTORTION + NOISE vs
FREQUENCY
SETTLING TIME vs GAIN
5000
RL = 600W
VOUT = 2Vrms
BW = 80kHz
4500
4000
Settling Time (ns)
THD + Noise (%)
0.01
0.001
3500
3000
2500
2000
1500
0.01%
1000
0.1%
500
0.0001
0
10
100
1k
10k
100k
1
Frequency (Hz)
Figure 17.
8
10
Noninverting Gain (V/V)
Figure 18.
Submit Documentation Feedback
100
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, VS = ±6V, RL = 10kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.
SMALL-SIGNAL OVERSHOOT vs CAPACITIVE LOAD
OFFSET VOLTAGE PRODUCTION DISTRIBUTION
90
VS = ±5V
80
60
G = +1
Population
Overshoot (%)
70
50
40
G = –1
CF = 3pF
30
20
100
1000
–12 0
– 11 0
–10 0
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
10
20
30
40
50
60
70
80
90
100
11 0
120
130
140
150
10
–13 0
0
–15 0
–14 0
G = +5
CF = 1pF
10
Capacitive Load (pF)
Offset Voltage (mV)
Figure 19.
Figure 20.
OFFSET VOLTAGE DRIFT PRODUCTION DISTRIBUTION
(0°C TO +85°C)
OFFSET VOLTAGE DRIFT PRODUCTION DISTRIBUTION
(–40°C TO +125°C)
VS = ±5V
0
0
0 .1
0 .2
0 .3
0 .4
0 .5
0 .6
0 .7
0 .8
0 .9
1 .0
1 .1
1 .2
1 .3
1 .4
1 .5
1 .6
1 .7
1 .8
1 .9
2 .0
2 .1
2 .2
2 .3
2 .4
2 .5
2 .6
2 .7
2 .8
2 .9
3 .0
Population
Population
VS = ±5V
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
Offset Voltage Drift (mV/°C)
Offset Voltage Drift (mV/°C)
Figure 21.
Figure 22.
OFFSET VOLTAGE vs TEMPERATURE
SMALL-SIGNAL STEP RESPONSE
300
G = +1
RL = 10kW
CL = 20pF
VS = ± 5V
4s
100
10mV/div
Offset Voltage (m V)
200
0
–100
4s
–200
7 Representative Units Shown
–300
–50
–25
0
25
50
75
100
125
100ns/div
Temperature (° C)
Figure 23.
Figure 24.
Submit Documentation Feedback
9
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
TYPICAL CHARACTERISTICS (continued)
At TA = +25°C, VS = ±6V, RL = 10kΩ connected to VS/2, and VOUT = VS/2, unless otherwise noted.
LARGE-SIGNAL STEP RESPONSE
SMALL-SIGNAL STEP RESPONSE
CF = 2pF
G = +1
RL = 10kW
CL = 20pF
CF = 3pF
1V/div
10mV/div
CF = 4pF
CF
G = –1
RF
10kW
10kW
O PA 7 2 7
CL
20pF
400ns/div
200ns/div
Figure 25.
Figure 26.
LARGE-SIGNAL STEP RESPONSE
1V/div
CF
4pF
G = –1
RF
10kW
"
10kW
O PA 7 2 7
CL
20pF
400ns/div
Figure 27.
10
Submit Documentation Feedback
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
APPLICATIONS INFORMATION
The OPA727 and OPA728 family of op amps use
e-trim, an adjustment to offset voltage and
temperature drift made during the final steps of
manufacturing after the plastic molding is completed.
This compensates for performance shifts that can
occur during the molding process. Through e-trim,
the OPA727 and OPA728 deliver excellent offset
voltage (150µV max) and extremely low offset
voltage drift (1.5µV/°C). Additionally, these 20MHz
CMOS op amps have a fast slew rate, low noise, and
excellent PSRR, CMRR, and AOL. They can operate
on typically 4.3mA quiescent current from a single (or
split) supply in the range of 4V to 12V (±2V to ±6V),
making them highly versatile and easy to use. They
are stable in a unity-gain configuration.
Common-mode rejection is excellent throughout the
input voltage range from V– to (V+) – 3V. CMRR
decreases somewhat as the common-mode voltage
extends to (V+) – 2.5V, but remains very good and is
tested throughout this range. See the Electrical
Characteristics table for details.
a) Single-Supply Configuration
Enable
+12V
Digital
Logic
REF
VREF = DGND
Power-supply pins should be bypassed with 1nF
ceramic capacitors in parallel with 1µF tantalum
capacitors.
b) Dual-Supply Configuration
OPERATING VOLTAGE
Enable
OPA727 series op amps require approximately
4.3mA quiescent current. The enable/shutdown
feature of the OPA728 allows the op amp to be shut
off to reduce this current to approximately 6µA.
The enable/shutdown input is referenced to the
Enable Reference Pin, REF (see Pin Configurations).
This pin can be connected to logic ground in
dual-supply op amp configurations to avoid
level-shifting the enable logic signal, as shown in
Figure 28.
The Enable Reference Pin voltage, VREF, must not
exceed (V+) – 2V. It may be set as low as V–. The
amplifier is enabled when the Enable Pin voltage is
greater than VREF + 2V. The amplifier is disabled
(shutdown) if the Enable Pin voltage is less than
VREF + 0.8V. The Enable Pin is connected to internal
pull-up circuitry and will enable the device if left
unconnected.
OPA728
VOUT
REF
VREF = DGND
-5V
Figure 28. Enable Reference Pin Connection for
Single- and Dual-Supply Configurations
INPUT OVER-VOLTAGE PROTECTION
Device inputs are protected by ESD diodes that will
conduct if the input voltages exceed the power
supplies by more than approximately 300mV.
Momentary voltages greater than 300mV beyond the
power supply can be tolerated if the current is limited
to 10mA. This is easily accomplished with an input
resistor in series with the op amp, as shown in
Figure 29. The OPA727 series features no phase
inversion when the inputs extend beyond supplies, if
the input is current limited.
V+
IOVERLOAD
10mA max
R
COMMON-MODE VOLTAGE RANGE
+5V
Digital
Logic
OPA727 series op amps are specified from 4V to
12V supplies over a temperature range of –40°C to
+125°C. They will operate well in ±5V or +5V to
+12V power-supply systems. Parameters that vary
significantly with operating voltage or temperature
are shown in the Typical Characteristics.
ENABLE/SHUTDOWN
VOUT
OPA728
VOUT
OPA727
VIN
The input common-mode voltage range of the
OPA727 and OPA728 series extends from V– to
(V+) – 2.5V.
V-
Figure 29. Input Current Protection for Voltages
Exceeding the Supply Voltage
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11
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
RAIL-TO-RAIL OUTPUT
+5V
A class AB output stage with common-source
transistors is used to achieve rail-to-rail output. This
output stage is capable of driving heavy loads
connected to any point between V+ and V–. For light
resistive loads (>100kΩ), the output voltage can
swing to 150mV from the supply rail, while still
maintaining excellent linearity (AOL > 110dB). With
1kΩ resistive loads, the output is specified to swing
to within 250mV from the supply rails with excellent
linearity (see the Typical Characteristics curve,
Output Voltage Swing vs Output Current).
+5V
75W
OPA727
VIN
±2.5V
330pF
AIN
ADS8342
16-Bit ADC
Common
-5V
-5V
Figure 31. OPA727 Driving an ADC
TRANSIMPEDANCE AMPLIFIER
CAPACITIVE LOAD AND STABILITY
Capacitive load drive is dependent upon gain and
the overshoot requirements of the application.
Increasing the gain enhances the ability of the
amplifier to drive greater capacitive loads (see the
Typical
Characteristics
curve,
Small-Signal
Overshoot vs Capacitive Load).
One method of improving capacitive load drive in the
unity-gain configuration is to insert a 10Ω to 20Ω
resistor inside the feedback loop, as shown in
Figure 30. This reduces ringing with large capacitive
loads while maintaining DC accuracy.
V+
RS
20W
OPA727
VOUT
Wide bandwidth, low input bias current, and low
input voltage and current noise make the OPA727 an
ideal wideband photodiode transimpedance amplifier.
Low-voltage noise is important because photodiode
capacitance causes the effective noise gain of the
circuit to increase at high frequency.
The key elements to a transimpedance design, as
shown in Figure 32, are the expected diode
capacitance (CD), which should include the parasitic
input common-mode and differential-mode input
capacitance (4pF + 5pF for the OPA727); the desired
transimpedance gain (RF); and the GBW for the
OPA727 (20MHz). With these three variables set, the
feedback capacitor value (CF) can be set to control
the frequency response. CF includes the stray
capacitance of RF, which is 0.2pF for a typical
surface-mount resistor.
VIN
CL
RL
(1)
CF
< 1pF
Figure 30. Series Resistor in Unity-Gain Buffer
Configuration Improves Capacitive Load Drive
RF
10MW
DRIVING FAST 16-BIT ADCs
The OPA727 series is optimized for driving fast
16-bit ADCs such as the ADS8342. The OPA727 op
amps buffer the converter input capacitance and
resulting charge injection, while providing signal gain.
Figure 31 shows the OPA727 in a single-ended
method of interfacing to the ADS8342 16-bit,
250kSPS, 4-channel ADC with an input range of
±2.5V. The OPA727 has demonstrated excellent
settling time to the 16-bit level within the 600ns
acquisition time of the ADS8342. The RC filter,
shown in Figure 31, has been carefully tuned for best
noise and settling performance. It may need to be
adjusted for different op amp configurations. Refer to
the ADS8342 data sheet (available for download at
www.ti.com) for additional information on this
product.
12
+5V
l
CD
OPA727
VOUT
-5V
NOTE: (1) CF is optional to prevent gain peaking.
It includes the stray capacitance of RF.
Figure 32. Dual-Supply Transimpedance
Amplifier
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OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
To achieve a maximally-flat, 2nd-order Butterworth
frequency response, the feedback pole should be set
to:
1
+
2pR FCF
GBW
Ǹ4pR
C
F
D
(1)
Bandwidth is calculated by:
f *3dB +
GBW Hz
Ǹ2pR
C
F
D
(2)
For even higher transimpedance bandwidth, the
high-speed CMOS OPA380 (90MHz GBW), OPA354
(100MHz GBW), OPA300 (180MHz GBW), OPA355
(200MHz GBW), or OPA656, OPA657 (400MHz
GBW) may be used.
For single-supply applications, the +IN input can be
biased with a positive dc voltage to allow the output
to reach true zero when the photodiode is not
exposed to any light, and respond without the added
delay that results from coming out of the negative
rail; this is shown in Figure 33. This bias voltage also
appears across the photodiode, providing a reverse
bias for faster operation.
(1)
CF
< 1pF
RF
10MW
V+
l
OPA727
VOUT
+VBias
NOTE: (1) CF is optional to prevent gain peaking.
It includes the stray capacitance of RF.
Figure 33. Single-Supply Transimpedance
Amplifier
For additional information, refer to Application
Bulletin (SBOA055), Compensate Transimpedance
Amplifiers Intuitively, available for download at
www.ti.com.
OPTIMIZING THE TRANSIMPEDANCE
CIRCUIT
To achieve the best performance, components
should be selected according to the following
guidelines:
1. For lowest noise, select RF to create the total
required gain. Using a lower value for RF and
adding gain after the transimpedance amplifier
generally produces poorer noise performance.
The noise produced by RF increases with the
square-root of RF, whereas the signal
increases linearly. Therefore, signal-to-noise
ratio is improved when all the required gain is
placed in the transimpedance stage.
2. Minimize photodiode capacitance and stray
capacitance at the summing junction (inverting
input). This capacitance causes the voltage
noise of the op amp to be amplified
(increasing amplification at high frequency).
Using a low-noise voltage source to
reverse-bias a photodiode can significantly
reduce its capacitance. Smaller photodiodes
have lower capacitance. Use optics to
concentrate light on a small photodiode.
3. Noise increases with increased bandwidth.
Limit the circuit bandwidth to only that
required. Use a capacitor across the RF to
limit bandwidth, even if not required for
stability.
4. Circuit board leakage can degrade the
performance of an otherwise well-designed
amplifier. Clean the circuit board carefully. A
circuit board guard trace that encircles the
summing junction and is driven at the same
voltage can help control leakage.
For additional information, refer to the Application
Bulletins Noise Analysis of FET Transimpedance
Amplifiers (SBOA060), and Noise Analysis for
High-Speed Op Amps (SBOA066), available for
download at the TI web site.
Submit Documentation Feedback
13
OPA727,, OPA2727
OPA4727, OPA728
www.ti.com
SBOS314H – SEPTEMBER 2004 – REVISED APRIL 2007
C3
2.2nF
C1
1nF
R1
1.93kW
R2
15.9kW
R3
2.07kW
1/2
OPA2727
R4
22.3kW
1/2
OPA2727
VO
C4
100pF
C2
330pF
DC Gain = 1
Cutoff Frequency = 50kHz
Note:
FilterPro is a low-pass filter design program available for download at no cost from TI’s web site (www.ti.com). The
program can be used to determine component values for other cutoff frequencies or filter types.
Figure 34. Four-Pole Butterworth Sallen-Key Low-Pass Filter
DFN PACKAGE
LAYOUT GUIDELINES
The OPA727 series uses the DFN-8 (also known as
SON), which is a QFN package with lead contacts on
only two sides of the bottom of the package. This
leadless, near-chip-scale package maximizes board
space and enhances thermal and electrical
characteristics through an exposed pad.
The leadframe die pad should be soldered to a
thermal pad on the PCB. A mechanical data sheet
showing an example layout is attached at the end of
this data sheet. Refinements to this layout may be
required based on assembly process requirements.
Mechanical drawings located at the end of this data
sheet list the physical dimensions for the package
and pad. The five holes in the landing pattern are
optional, and are intended for use with thermal vias
that connect the leadframe die pad to the heatsink
area on the PCB.
DFN packages are physically small, have a smaller
routing area, improved thermal performance, and
improved electrical parasitics, with a pinout scheme
that is consistent with other commonly-used
packages, such as SO and MSOP. Additionally, the
absence of external leads eliminates bent-lead
issues.
The DFN package can be easily mounted using
standard printed circuit board (PCB) assembly
techniques. See Application Note, QFN/SON PCB
Attachment (SLUA271) and Application Report,
Quad Flatpack No-Lead Logic Packages (SCBA017),
both available for download at www.ti.com.
Soldering the exposed pad significantly improves
board-level reliability during temperature cycling, key
push, package shear, and similar board-level tests.
Even with applications that have low-power
dissipation, the exposed pad must be soldered to the
PCB to provide structural integrity and long-term
reliability.
The exposed leadframe die pad on the bottom of
the package should be connected to V–.
14
Submit Documentation Feedback
PACKAGE OPTION ADDENDUM
www.ti.com
14-Oct-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
OPA2727AID
ACTIVE
SOIC
D
8
75
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 85
O2727A
2727A
Samples
OPA2727AIDR
ACTIVE
SOIC
D
8
2500
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 85
O2727A
2727A
Samples
OPA2727AIDRBR
ACTIVE
SON
DRB
8
2500
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 85
NSD
Samples
OPA2727AIDRBT
ACTIVE
SON
DRB
8
250
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 85
NSD
Samples
OPA4727AIPW
ACTIVE
TSSOP
PW
14
90
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
OPA4727
Samples
OPA4727AIPWR
ACTIVE
TSSOP
PW
14
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
OPA4727
Samples
OPA727AIDGKR
ACTIVE
VSSOP
DGK
8
2500
RoHS & Green
Call TI | NIPDAU
Level-2-260C-1 YEAR
-40 to 85
AUE
Samples
OPA727AIDGKT
ACTIVE
VSSOP
DGK
8
250
RoHS & Green
Call TI | NIPDAU
Level-2-260C-1 YEAR
-40 to 85
AUE
Samples
OPA727AIDRBT
ACTIVE
SON
DRB
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
NSF
Samples
OPA728AIDGKT
ACTIVE
VSSOP
DGK
8
250
RoHS & Green
Call TI | NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
AUF
Samples
OPA728AIDRBT
ACTIVE
SON
DRB
8
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
NSG
Samples
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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