ETC OPA337/OPA2337/OPA338/OPA2338

OPA337
OPA2337
OPA338
OPA2338
®
OPA
337
OPA
233
7
OPA
233
8
For most current data sheet and other product
information, visit www.burr-brown.com
MicroSIZE, Single-Supply
CMOS OPERATIONAL AMPLIFIERS
MicroAmplifier ™ Series
FEATURES
DESCRIPTION
● MicroSIZE PACKAGES:
SOT-23-5
SOT-23-8
● SINGLE-SUPPLY OPERATION
● RAIL-TO-RAIL OUTPUT SWING
● FET-INPUT: IB = 10pA max
● HIGH SPEED:
OPA337: 3MHz, 1.2V/µs (G = 1)
OPA338: 12.5MHz, 4.6V/µs (G = 5)
● OPERATION FROM 2.5V to 5.5V
● HIGH OPEN-LOOP GAIN: 120dB
● LOW QUIESCENT CURRENT: 525µA/amp
● SINGLE AND DUAL VERSIONS
The OPA337 series and OPA338 series rail-to-rail output
CMOS operational amplifiers are designed for low cost and
miniature applications. Packaged in the new SOT-23-8, the
OPA2337EA and OPA2338EA are Burr-Brown’s smallest
dual op amps. At only 1/4 the size of a conventional SO-8
surface mount, they are ideal for space-sensitive applications.
Performance is not sacrificed for size. Utilizing advanced
CMOS technology, OPA337 and OPA338 op amps provide low bias current, high-speed operation, high openloop gain, and rail-to-rail output swing. They operate on a
single supply with operation as low as 2.5V while drawing
only 525µA quiescent current. In addition, the input common-mode voltage range includes ground—ideal for singlesupply operations.
The OPA337 series is unity-gain stable. The OPA338
series is optimized for gains greater than or equal to five.
They are easy to use and free from phase inversion and
overload problems found in some other op amps. Excellent
performance is maintained as the amplifiers swing to their
specified limits. The dual versions feature completely
independent circuitry for lowest crosstalk and freedom
from interaction, even when overdriven or overloaded.
The OPA337 packages are the tiny SOT-23-5 surface
mount, SO-8 surface mount, and 8-pin DIP packages.
In addition to the miniature SOT-23-8 surface-mount
package, the OPA2337 is available in SO-8 surfacemount and 8-pin DIP packages. The OPA338 packages
are the SOT-23-5 and SO-8 surface mounts. The OPA2338
packages are the SOT-23-8 and SO-8 surface mounts.
APPLICATIONS
●
●
●
●
●
●
●
BATTERY-POWERED INSTRUMENTS
PHOTODIODE PRE-AMPS
MEDICAL INSTRUMENTS
TEST EQUIPMENT
AUDIO SYSTEMS
DRIVING ADCs
CONSUMER PRODUCTS
SPICE Model available at www.burr.com
OPA337, OPA338
OPA337, OPA338
NC
1
8
NC
–In
2
7
V+
+In
3
6
Output
V–
4
5
NC
Out 1
OPA2337, OPA2338
5
V+
V– 2
–In A
+In 3
4
–In
SOT-23-5
8-Pin DIP(1), SO-8
Out A
NOTE: (1) DIP versions for OPA337, OPA2337 only.
1
2
+In A
3
V–
4
A
B
8
V+
7
Out B
6
–In B
5
+In B
8-Pin DIP(1), SO-8, SOT-23-8
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
© 1997 Burr-Brown Corporation
PDS-1410C
PDS-1410C
Printed in U.S.A. February, 1999
SPECIFICATIONS: VS = 2.7V to 5.5V
At TA = +25°C, and RL = 25kΩ connected to VS/2, unless otherwise noted.
Boldface limits apply over the specified temperature range, –40°C to +85°C, VS = 5V.
OPA337NA, UA, PA
OPA2337EA, UA, PA
OPA338NA, UA
OPA2338EA, UA
PARAMETER
CONDITION
OFFSET VOLTAGE
Input Offset Voltage
TA = –40°C to +85°C
vs Temperature
vs Power Supply Rejection Ratio
TA = –40°C to +85°C
Channel Separation (dual versions)
dVOS/dT
PSRR
NOISE
Input Voltage Noise, f = 0.1Hz to 10Hz
Input Voltage Noise Density, f = 1kHz
Current Noise Density, f = 1kHz
±2
25
VS = 2.7V to 5.5V
VS = 2.7V to 5.5V
dc
IOS
±0.2
See Typical Curve
±0.2
en
in
6
26
0.6
IB
VCM
CMRR
TA = –40°C to +85°C
–0.2V < VCM < (V+) – 1.2V
–0.2V < VCM < (V+) – 1.2V
AOL
TA = –40°C to +85°C
RL = 25kΩ, 125mV < VO < (V+) – 125mV
RL = 25kΩ, 125mV < VO < (V+) – 125mV
RL = 5kΩ, 500mV < VO < (V+) – 500mV
RL = 5kΩ, 500mV < VO < (V+) – 500mV
MAX
UNITS
±3
mV
mV
µV/°C
µV/V
µV/V
µV/V
±3.5
125
125
0.3
–0.2
74
74
INPUT IMPEDANCE
Differential
Common-Mode
OPEN-LOOP GAIN
Open-Loop Voltage Gain
TA = –40°C to +85°C
TYP(1)
±0.5
VOS
INPUT BIAS CURRENT
Input Bias Current
TA = –40°C to +85°C
Input Offset Current
INPUT VOLTAGE RANGE
Common-Mode Voltage Range
Common-Mode Rejection Ratio
TA = –40°C to +85°C
MIN
100
100
100
100
±10
pA
±10
pA
µVp-p
nV/√Hz
fA/√Hz
90
(V+) – 1.2
V
dB
dB
1013 || 2
1013 || 4
Ω || pF
Ω || pF
120
dB
dB
dB
dB
114
OPA337 FREQUENCY RESPONSE
Gain-Bandwidth Product
GBW
Slew Rate
SR
Settling Time: 0.1%
0.01%
Overload Recovery Time
Total Harmonic Distortion + Noise
THD+N
VS = 5V, G = 1
VS = 5V, G = 1
VS = 5V, 2V Step, CL = 100pF, G = 1
VS = 5V, 2V Step, CL = 100pF, G = 1
VIN • G = VS
VS = 5V, VO = 3Vp-p, G = 1, f = 1kHz
3
1.2
2
2.5
2
0.001
MHz
V/µs
µs
µs
µs
%
OPA338 FREQUENCY RESPONSE
Gain-Bandwidth Product
GBW
Slew Rate
SR
Settling Time: 0.1%
0.01%
Overload Recovery Time
Total Harmonic Distortion + Noise
THD+N
VS = 5V, G = 5
VS = 5V, G = 5
VS = 5V, 2V Step, CL = 100pF, G = 5
VS = 5V, 2V Step, CL = 100pF, G = 5
VIN • G = VS
VS = 5V, VO = 3Vp-p, G = 5, f = 1kHz
12.5
4.6
1.4
1.9
0.5
0.0035
MHz
V/µs
µs
µs
µs
%
RL = 25kΩ, AOL ≥ 100dB
RL = 25kΩ, AOL ≥ 100dB
RL = 5kΩ, AOL ≥ 100dB
RL = 5kΩ, AOL ≥ 100dB
40
OUTPUT
Voltage Output Swing from Rail(2)
TA = –40°C to +85°C
TA = –40°C to +85°C
Short-Circuit Current
Capacitive Load Drive
POWER SUPPLY
Specified Voltage Range
Minimum Operating Voltage
Quiescent Current (per amplifier)
TA = –40°C to +85°C
150
IQ
TA = –40°C to +85°C
2.7
2.5
0.525
IO = 0
IO = 0
mV
mV
mV
mV
mA
5.5
V
V
mA
mA
±9
See Typical Curve
ISC
CLOAD
VS
125
125
500
500
1
1.2
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.
®
OPA337, OPA2337
OPA338, OPA2338
2
SPECIFICATIONS: VS = 2.7V to 5.5V
(CONT)
At TA = +25°C, and RL = 25kΩ connected to VS/2, unless otherwise noted.
Boldface limits apply over the specified temperature range, –40°C to +85°C, VS = 5V.
OPA337NA, UA, PA
OPA2337EA, UA, PA
OPA338NA, UA
OPA2338EA, UA
PARAMETER
CONDITION
TEMPERATURE RANGE
Specified Range
Operating Range
Storage Range
Thermal Resistance
SOT-25-5 Surface Mount
SOT-23-8 Surface Mount
SO-8 Surface Mount
8-Pin DIP
MIN
TYP
–40
–55
–55
MAX
UNITS
+85
+125
+125
°C
°C
°C
θJA
°C/W
°C/W
°C/W
°C/W
200
200
150
100
NOTES: (1) VS = 5V. (2) Output voltage swings are measured between the output and negative and positive power supply rails.
ABSOLUTE MAXIMUM RATINGS(1)
ELECTROSTATIC
DISCHARGE SENSITIVITY
Supply Voltage ................................................................................... 5.5V
Input Voltage(2) .................................................. (V–) –0.5V to (V+) +0.5V
Input Current(2) ................................................................................. 10mA
Output Short Circuit(3) .............................................................. Continuous
Operating Temperature .................................................. –55°C to +125°C
Storage Temperature ..................................................... –55°C to +125°C
Junction Temperature ...................................................................... 150°C
Lead Temperature (soldering, 10s) ................................................. 300°C
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.
NOTES: (1) Stresses above these ratings may cause permanent damage.
Exposure to absolute maximum ratings for extended periods may degrade
device reliability. (2) Input signal voltage is limited by internal diodes
connected to power supplies. See text. (3) Short circuit to ground, one
amplifier per package.
PACKAGE/ORDERING INFORMATION
DESCRIPTION
PACKAGE
PACKAGE
DRAWING
NUMBER(1)
OPA337 Series
OPA337NA
Single, G = 1 Stable
5-Lead SOT-23-5
331
–40°C to +85°C
C37
"
"
"
"
"
"
Single, G = 1 Stable
Single, G = 1 Stable
8-Pin DIP
SO-8 Surface Mount
006
182
–40°C to +85°C
–40°C to +85°C
OPA337PA
OPA337UA
PRODUCT
OPA337PA
OPA337UA
"
SPECIFIED
TEMPERATURE
RANGE
PACKAGE
MARKING
ORDERING
NUMBER(2)
TRANSPORT
MEDIA
OPA337NA/250
OPA337NA/3K
OPA337PA
OPA337UA
OPA337UA/2K5
Tape and Reel
Tape and Reel
Rails
Rails
Tape and Reel
OPA2337EA/250
OPA2337EA/3K
OPA2337PA
OPA2337UA
OPA2337UA/2K5
Tape and Reel
Tape and Reel
Rails
Rails
Tape and Reel
OPA338NA/250
OPA338NA/3K
OPA338UA
OPA338UA/2K5
Tape and Reel
Tape and Reel
Rails
Tape and Reel
OPA2338EA/250
OPA2338EA/3K
OPA2338UA
OPA2338UA/2K5
Tape and Reel
Tape and Reel
Rails
Tape and Reel
"
"
"
"
"
Dual, G = 1 Stable
8-Lead SOT-23-8
348
–40°C to +85°C
A7
"
"
"
"
"
Dual, G = 1 Stable
Dual, G = 1 Stable
8-Pin DIP
SO-8 Surface Mount
006
182
–40°C to +85°C
–40°C to +85°C
OPA2337PA
OPA2337UA
"
"
"
"
"
"
OPA338 Series
OPA338NA
Single, G ≥ 5 Stable
5-Lead SOT-23-5
331
–40°C to +85°C
A38
"
"
"
"
"
"
182
–40°C to +85°C
OPA338UA
"
"
"
"
"
Dual, G ≥ 5 Stable
8-Lead SOT-23-8
348
–40°C to +85°C
A8
"
Dual, G ≥ 5 Stable
"
"
"
"
SO-8 Surface Mount
182
–40°C to +85°C
OPA2338UA
"
"
"
"
"
OPA2337EA
"
OPA2337PA
OPA2337UA
OPA338UA
"
OPA2338EA
"
OPA2338UA
"
Single, G ≥ 5 Stable SO-8 Surface Mount
NOTES: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. (2) 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 “OPA2337UA/2K5” will get a single
2500-piece Tape and Reel. For detailed Tape and Reel mechanical information, refer to Appendix B of Burr-Brown IC Data Book.
3
OPA337, OPA2337
OPA338, OPA2338
®
TYPICAL PERFORMANCE CURVES
At TA = +25°C, VS = +5V, and RL = 25kΩ connected to VS/2, unless otherwise noted.
POWER SUPPLY REJECTION RATIO AND
COMMON-MODE REJECTION RATIO vs FREQUENCY
OPEN-LOOP GAIN/PHASE vs FREQUENCY
0
160
–45
φ
–90
80
60
G
80
–135
40
PSRR, CMRR (dB)
120
100
+PSRR
90
Phase (°)
Open-Loop Gain (dB)
100
OPA337
OPA338
140
–PSRR
70
60
50
CMRR
40
30
20
–180
0
20
10
–20
1
10
100
1k
10k
100k
1M
10M
1
10
100
1k
Frequency (Hz)
INPUT VOLTAGE AND CURRENT NOISE
SPECTRAL DENSITY vs FREQUENCY
100k
1M
10M
CHANNEL SEPARATION vs FREQUENCY
1k
1k
140
10
10
1
1
Current Noise
Channel Separation (dB)
100
100
Current Noise (fA√Hz)
Voltage Noise
Voltage Noise (nV√Hz)
10k
Frequency (Hz)
130
120
110
100
Dual Versions
90
0.1
0.1
1
10
100
1k
10k
100k
80
100
1M
Frequency (Hz)
1k
10k
100k
1M
Frequency (Hz)
INPUT BIAS CURRENT
vs INPUT COMMON-MODE VOLTAGE
INPUT BIAS CURRENT vs TEMPERATURE
100
0.5
Input Bias Current (pA)
Input Bias Current (pA)
0.4
10
1
0.1
0.3
0.2
0.1
0
0.01
–0.1
–75
–50
–25
0
25
50
75
100
125
–1
Temperature (°C)
®
OPA337, OPA2337
OPA338, OPA2338
0
1
2
3
Common-Mode Voltage (V)
4
4
5
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C, VS = +5V, and RL = 25kΩ connected to VS/2, unless otherwise noted.
QUIESCENT CURRENT AND SHORT-CIRCUIT CURRENT
vs TEMPERATURE
AOL, CMRR, PSRR vs TEMPERATURE
600
130
120
550
120
110
110
100
PSRR
100
PSRR (dB)
AOL, CMRR (dB)
AOL
IQ
11
10
500
–ISC
450
9
+ISC
400
8
80
350
7
70
300
90
90
12
Short-Circuit Current (mA)
130
Quiescent Current (µA)
140
CMRR
80
–75
–50
–25
0
25
50
75
100
6
–75
125
–50
–25
±12
6
650
±10
5
600
±8
±6
±4
IQ
±2
450
400
Output Voltage (Vp-p)
+ISC
–ISC
3.0
3.5
4.0
4.5
5.0
OPA338
3
OPA337
2
100k
1M
10M
OUTPUT VOLTAGE SWING vs OUTPUT CURRENT
2.5
VS = ±2.5V
RL Tied to Ground
2.0
Output Voltage (V)
THD+N (%)
1.5
G = +10, RL = 5kΩ, 25kΩ
G = +5, RL = 5kΩ, 25kΩ
G = +1
RL = 25kΩ
100
–55°C
0.5
25°C
0
125°C
–0.5
–1.0
–55°C
Sinking
–2.0
–2.5
0.0001
20
Sourcing
1.0
–1.5
VO = 3Vp-p
OPA337
OPA338
100M
Frequency (Hz)
0.1
0.001
125
4
0
10k
5.5
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
RL = 5kΩ
100
Maximum output
voltage without slew
rate-induced distortion.
Supply Voltage (V)
0.01
75
1
0
2.5
50
MAXIMUM OUTPUT VOLTAGE vs FREQUENCY
700
Short-Circuit Current (mA)
Quiescent Current (µA)
QUIESCENT AND SHORT-CIRCUIT CURRENT
vs SUPPLY VOLTAGE
500
25
Temperature (°C)
Temperature (°C)
550
0
1k
10k
0
20k
±1
±2
±3
±4
±5
±6
±7
±8
Output Current (mA)
Frequency (Hz)
5
OPA337, OPA2337
OPA338, OPA2338
®
TYPICAL PERFORMANCE CURVES (CONT)
At TA = +25°C, VS = +5V, and RL = 25kΩ connected to VS/2, unless otherwise noted.
OFFSET VOLTAGE DRIFT
PRODUCTION DISTRIBUTION
OFFSET VOLTAGE
PRODUCTION DISTRIBUTION
25
30
Typical distribution
of packaged units
25
20
Percent of Amplifiers (%)
Percent of Amplifiers (%)
Typical distribution
of packaged units.
15
10
5
20
15
10
5
0
3.0
2.5
2.0
1.5
1.0
0.5
0.0
–0.5
–1.0
–1.5
–2.0
–2.5
–3.0
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0
Offset Voltage Drift (µV/°C)
Offset Voltage (mV)
SETTLING TIME vs CLOSED-LOOP GAIN
SMALL-SIGNAL OVERSHOOT vs LOAD CAPACITANCE
100
60
50
Overshoot (%)
10
OPA338
OPA337
OPA338
(G = ±5)
40
OPA337
(G = ±1)
30
OPA337
(G = ±10)
20
OPA338
(G = ±50)
10
0.1%
1
0
1
10
100
1k
10
100
Closed-Loop Gain (V/V)
1k
Load Capacitance (pF)
LARGE-SIGNAL STEP RESPONSE
CL = 100pF, VS = +5V
SMALL-SIGNAL STEP RESPONSE
C L = 100pF, VS = +5V
OPA338
G=5
500mV/div
OPA337
G=1
50mV/div
Settling Time (µs)
0.01%
OPA337
G=1
OPA338
G=5
2µs/div
1µs/div
®
OPA337, OPA2337
OPA338, OPA2338
6
10k
APPLICATIONS INFORMATION
+5V
The OPA337 series and OPA338 series are fabricated on a
state-of-the-art CMOS process. The OPA337 series is unitygain stable. The OPA338 series is optimized for gains
greater than or equal to five. Both are suitable for a wide
range of general purpose applications. Power supply pins
should be bypassed with 0.01µF ceramic capacitors.
IOVERLOAD
10mA max
FIGURE 2. Input Current Protection for Voltages Exceeding
the Supply Voltage.
The OPA337 series and OPA338 series can operate from a
+2.5V to +5.5V single supply with excellent performance.
Unlike most op amps which are specified at only one supply
voltage, these op amps are specified for real-world applications; a single limit applies throughout the +2.7V to +5.5V
supply range. This allows a designer to have the same
assured performance at any supply voltage within the specified voltage range. Most behavior remains unchanged
throughout the full operating voltage range. Parameters
which vary significantly with operating voltage are shown in
typical performance curves.
USING THE OPA338 IN LOW GAINS
The OPA338 series is optimized for gains greater than or
equal to five. It has significantly wider bandwidth (12.5MHz)
and faster slew rate (4.6V/µs) when compared to the OPA337
series. The OPA338 series can be used in lower gain configurations at low frequencies while maintaining its high
slew rate with the proper compensation.
Figure 3 shows the OPA338 in a unity-gain buffer configuration. At dc, the compensation capacitor C1 is effectively
“open” resulting in 100% feedback (closed-loop gain = 1).
As frequency increases, C1 becomes lower impedance and
closed-loop gain increases, eventually becoming 1 + R2/R1
(in this case five, which is equal to the minimum gain
required for stability).
OPA337, VIN = ±3V Greater Than VS = ±2.5V
VOUT, G = –1
(not limited by
input commonmode range.)
The required compensation capacitor value can be determined from the following equation:
C1 = 1/(2πfCR1)
0
Since fC may shift with process variations, it is recommended that a value less than fC be used for determining C1.
With fC = 1MHz and R1 = 2.5kΩ, the compensation capacitor is about 68pF.
G = ±1
–3V
VOUT
5kΩ
OPERATING VOLTAGE
3V
OPA337
VIN
VOUT, G = +1
(limited by input
common-mode
range)
The selection of the compensation capacitor C1 is important.
A proper value ensures that the closed-loop circuit gain is
greater than or equal to five at high frequencies. Referring to
the “Open-Loop Gain vs Frequency” plot in the Typical
Performance Curves section, the OPA338 gain line (dashed
in the curve) has a constant slope (–20dB/decade) up to
approximately 3MHz. This frequency is referred to as fC.
Beyond fC the slope of the curve increases, suggesting that
closed-loop gains less than 5 are not appropriate.
FIGURE 1. OPA337—No Phase Inversion with Inputs
Greater than the Power Supply Voltage.
INPUT VOLTAGE
The input common-mode range extends from (V–) – 0.2V to
(V+) – 1.2V. For normal operation, inputs should be
limited to this range. The absolute maximum input voltage
is 500mV beyond the supplies. Inputs greater than the
input common-mode range but less than maximum input
voltage, while not valid, will not cause any damage to the
op amp. Furthermore, if input current is limited the inputs
may go beyond the power supplies without phase inversion (Figure 1) unlike some other op amps.
Improved slew rate (4.6V/µs) versus
OPA337 (1.2V/µs) in unity gain.
R2
10kΩ
R1
2.5kΩ
C1
68pF
Normally, input currents are 0.2pA. However, large inputs
(greater than 500mV beyond the supply rails) can cause
excessive current to flow in or out of the input pins.
Therefore, as well as keeping the input voltage below the
maximum rating, it is also important to limit the input
current to less than 10mA. This is easily accomplished
with an input resistor as shown in Figure 2.
OPA338
VOUT
VIN
C1 =
1
2πfCR1
Where fC is the frequency at which closed-loop
gains less than five are not appropriate—see text.
FIGURE 3. Compensation of OPA338 for Unity-Gain Buffer.
7
OPA337, OPA2337
OPA338, OPA2338
®
Figure 4 shows a compensation technique using an inverting
configuration. The low frequency gain is set by the resistor
ratio while the high frequency gain is set by the capacitor
ratio. As with the noninverting circuit, for frequencies above
fC the gain must be greater than the recommended minimum
stable gain for the op amp.
The capacitor values shown are the nearest standard values.
Capacitor values may need to be adjusted slightly to optimize performance. For more detailed information, consult
the OPA686 product data sheet.
Figure 5 shows the large-signal transient response using the
circuit given in Figure 4. As shown, the OPA338 is stable in
low gain applications and provides improved slew rate
performance when compared to the OPA337.
C2
15pF
Improved slew rate versus OPA337
(see Figure 5).
R2
10kΩ
R1
5kΩ
OPA338
C1
150pF
C2 =
OPA338
1
2πfCR2
500mV/div
VIN
VOUT
OPA337
, C1 = (GH –1) • C2
2µs/div
Where GH is the high frequency gain,
GH = 1 + C1/C2
FIGURE 5. G = 2, Slew-Rate Comparison of OPA338 and
OPA337.
FIGURE 4. Inverting Compensation Circuit of OPA338 for
Low Gain.
TYPICAL APPLICATION
Figure 6 shows the OPA2337 in a typical application. The
ADS7822 is a 12-bit, micro-power sampling analog-todigital converter available in the tiny MSOP-8 package. As
with the OPA2337, it operates with a supply voltage as
low as +2.7V. When used with the miniature SOT-23-8
package of the OPA2337, the circuit is ideal for spacelimited and low power applications. In addition, OPA2337’s
high input impedance allows large value resistors to be
used which results in small physical capacitors, further
reducing circuit size. For further information, consult the
ADS7822 product data sheet.
Resistors R1 and R2 are chosen to set the desired dc signal
gain. Then the value for C2 is determined as follows:
C2 = 1/(2πfCR2)
C1 is determined from the desired high frequency gain (GH):
C1 = (GH – 1) • C2
For a desired dc gain of 2 and high frequency gain of 10, the
following resistor and capacitor values result:
R1 = 10kΩ
C1 = 150pF
R2 = 5kΩ
C2 = 15pF
®
OPA337, OPA2337
OPA338, OPA2338
8
Passband 300Hz to 3kHz
V+ = +2.7V to 5V
R9
510kΩ
R1
1.5kΩ
R4
20kΩ
R2
1MΩ
C1
C3
Electret
Microphone(1)
R7
51kΩ
1/2
OPA2337E
1000pF
R3
1MΩ
R8
150kΩ
33pF
1/2
OPA2337E
R6
100kΩ
C2
1000pF
VREF 1
+IN
2
–IN
ADS7822
12-Bit A/D
3
NOTE: (1) Electret microphone
with internal transistor (FET)
powered by R1.
R5
20kΩ
V+ 8
DCLOCK
7 D
OUT
6
Serial
Interface
CS/SHDN
5
GND 4
G = 100
FIGURE 6. Low Power, Single-Supply, Speech Bandpass Filtered Data Acquisition System.
SOT-23-8
(Package Drawing #348)
SOT-23-5
(Package Drawing #331)
0.075
(1.905)
0.0375
(0.9525)
0.10
(2.54)
0.10
(2.54)
0.035
(0.889)
0.035
(0.889)
0.027
(0.686)
0.0375
(0.9525)
0.026
(0.66)
0.018
(0.457)
Refer to end of data sheet or Appendix C of Burr-Brown IC Data Book for
tolerances and detailed package drawing. For further information on solder
pads for surface-mount packages, consult Application Bulletin AB-132.
FIGURE 7. Recommended SOT-23-5 and SOT-23-8 Solder Footprints.
9
OPA337, OPA2337
OPA338, OPA2338
®