Datasheet

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INA326

INA327

SBOS222D – NOVEMBER 2001 – REVISED NOVEMBER 2004

www.ti.com

DESCRIPTION

The INA326 and INA327 (with shutdown) are high-perfor-

mance, low-cost, precision instrumentation amplifiers with

rail-to-rail input and output. They are true single-supply

instrumentation amplifiers with very low DC errors and input

common-mode ranges that extends beyond the positive and

negative rails. These features make them suitable for appli-

cations ranging from general-purpose to high-accuracy.

Excellent long-term stability and very low 1/f noise assure

low offset voltage and drift throughout the life of the product.

The INA326 (without shutdown) comes in the MSOP-8 pack-

age. The INA327 (with shutdown) is offered in an MSOP-10.

Both are specified over the industrial temperature range,

–40°C to +85°C, with operation from –40°C to +125°C.

FEATURES

● PRECISION

LOW OFFSET: 100µV (max)

LOW OFFSET DRIFT: 0.4

µV/°C (max)

EXCELLENT LONG-TERM STABILITY

VERY-LOW 1/f NOISE

● TRUE RAIL-TO-RAIL I/O

INPUT COMMON-MODE RANGE:

20mV Below Negative Rail to 100mV Above

Positive Rail

WIDE OUTPUT SWING: Within 10mV of Rails

SUPPLY RANGE: Single +2.7V to +5.5V

● SMALL SIZE

micro

PACKAGE: MSOP-8, MSOP-10

● LOW COST

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Precision, Rail-to-Rail I/O

INSTRUMENTATION AMPLIFIER

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.

APPLICATIONS

● LOW-LEVEL TRANSDUCER AMPLIFIER FOR

BRIDGES, LOAD CELLS, THERMOCOUPLES

● WIDE DYNAMIC RANGE SENSOR

MEASUREMENTS

● HIGH-RESOLUTION TEST SYSTEMS

● WEIGH SCALES

● MULTI-CHANNEL DATA ACQUISITION

SYSTEMS

● MEDICAL INSTRUMENTATION

● GENERAL-PURPOSE

INA326 AND INA327 RELATED PRODUCTS

PRODUCT FEATURES

INA337 Precision, 0.4

µV/°C Drift, Specified –40°C to +125°C

INA114 50µV V

, 0.5nA I

, 115dB CMR, 3mA I

, 0.25µV/°C Drift

INA118 50µV V

, 1nA I

, 120dB CMR, 385µA I

, 0.5µV/°C Drift

INA122 250µV V

, –10nA I

, 85µA I

, Rail-to-Rail Output, 3µV/°C Drift

INA128 50µV V

, 2nA I

, 125dB CMR, 750µA I

, 0.5µV/°C Drift

INA321 500µV V

, 0.5pA I

, 94dB CMRR, 60µA I

, Rail-to-Rail Output

INA326R

IN−

IN+

V+

V−

G = 2(R

)

Summary of content (24 pages)

PAGE 1
INA3 INA3 26 INA326 INA327 27 SBOS222D – NOVEMBER 2001 – REVISED NOVEMBER 2004 Precision, Rail-to-Rail I/O INSTRUMENTATION AMPLIFIER FEATURES DESCRIPTION ● PRECISION LOW OFFSET: 100µV (max) LOW OFFSET DRIFT: 0.4µV/°C (max) EXCELLENT LONG-TERM STABILITY VERY-LOW 1/f NOISE The INA326 and INA327 (with shutdown) are high-performance, low-cost, precision instrumentation amplifiers with rail-to-rail input and output.
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PACKAGE/ORDERING INFORMATION(1) PRODUCT PACKAGE-LEAD PACKAGE DESIGNATOR SPECIFIED TEMPERATURE RANGE PACKAGE MARKING ORDERING NUMBER TRANSPORT MEDIA, QUANTITY MSOP-8 DGK –40°C to +85°C B26 " " " " INA326EA/250 INA326EA/2K5 Tape and Reel, 250 Tape and Reel, 2500 MSOP-10 DGS –40°C to +85°C B27 " " " " INA327EA/250 INA327EA/2K5 Tape and Reel, 250 Tape and Reel, 2500 INA326 " INA327 " NOTE: (1) For the most current package and ordering information, download the latest version of th
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ELECTRICAL CHARACTERISTICS: VS = +2.7V to +5.5V BOLDFACE limits apply over the specified temperature range, TA = –40°C to +85°C At TA = +25°C, RL = 10kΩ, G = 100 (R1 = 2kΩ, R2 = 100kΩ), external gain set resistors, and IACOMMON = VS /2, with external equivalent filter corner of 1kHz, unless otherwise noted. INA326EA, INA327EA PARAMETER CONDITION INPUT Offset Voltage, RTI VOS VS = +5V, VCM = VS /2 Over Temperature vs Temperature dVOS/dT vs Power Supply PSR VS = +2.7V to +5.
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ELECTRICAL CHARACTERISTICS: VS = +2.7V to +5.5V (Cont.) BOLDFACE limits apply over the specified temperature range, TA = –40°C to +85°C At TA = +25°C, RL = 10kΩ, G = 100 (R1 = 2kΩ, R2 = 100kΩ), external gain set resistors, and IACOMMON = VS /2, with external equivalent filter corner of 1kHz, unless otherwise noted. INA326EA, INA327EA PARAMETER POWER SUPPLY Specified Voltage Range Quiescent Current Over Temperature CONDITION TYP MAX UNITS 2.4 +5.5 3.4 3.7 V mA mA 0.25 V V µs µs µA +2.
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TYPICAL CHARACTERISTICS At TA = 25°C, VS = +5V, Gain = 100, and RL = 10kΩ with external equivalent filter corner of 1kHz, unless otherwise noted.
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TYPICAL CHARACTERISTICS (Cont.) At TA = 25°C, VS = +5V, Gain = 100, and RL = 10kΩ with external equivalent filter corner of 1kHz, unless otherwise noted. INPUT OFFSET VOLTAGE vs TURN- ON TIME 1kHz FILTER, G = 100 INPUT OFFSET VOLTAGE vs WARM- UP TIME 10kHz FILTER, G = 100 Input Offset Voltage (20µV/div) Input Offset Voltage (20µV/div) Filter Settling Time Device Turn- On Time (75µs) 0 1 Turn- On Time (ms) 2 Device Turn- On Time Filter Settling Time 0 SMALL- SIGNAL RESPONSE G = 1, 10, AND 100 0.
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TYPICAL CHARACTERISTICS (Cont.) At TA = 25°C, VS = +5V, Gain = 100, and RL = 10kΩ with external equivalent filter corner of 1kHz, unless otherwise noted.
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TYPICAL CHARACTERISTICS (Cont.) At TA = 25°C, VS = +5V, Gain = 100, and RL = 10kΩ with external equivalent filter corner of 1kHz, unless otherwise noted. GAIN ERROR PRODUCTION DISTRIBUTION G = 100 −100 100.000 −110 31.600 −120 1.000 −130 0.316 −140 0.100 −150 0.030 −160 0.010 −170 0.003 −200 −180 −160 −140 −120 −100 −80 −60 −40 −20 0 20 40 60 80 100 120 140 160 180 200 −180 0 200k 400k 600k Frequency (Hz) Gain Error (m%) QUIESCENT CURRENT vs TEMPERATURE 2.0 VS = +5V 1.5 2.5 1.
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APPLICATIONS INFORMATION SETTING THE GAIN The INA326 is a 2-stage amplifier with each stage gain set by R1 and R2, respectively (see Figure 5, “Inside the INA326”, for details). Overall gain is described by the equation: Figure 1 shows the basic connections required for operation of the INA326. A 0.1µF capacitor, placed close to and across the power-supply pins is strongly recommended for highest accuracy. RoCo is an output filter that minimizes auto-correction circuitry noise.
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Following this design procedure for R1 produces the maximum possible input stage gain for best accuracy and lowest noise. Circuit layout and supply bypassing can affect performance. Minimize the stray capacitance on pins 1 and 8. Use recommended supply bypassing, including a capacitor directly from pin 7 to pin 4 (V+ to V–), even with dual (split) power supplies (see Figure 1).
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Applications sensitive to the spectral characteristics of highfrequency noise may require consideration of the spurious frequencies generated by internal clocking circuitry. “Spurs” occur at approximately 90kHz and its harmonics (see typical characteristic “Input-Referred Ripple Spectrum”) which may be reduced by additional filtering below 1kHz. Thermocouple INA326 5 Insufficient filtering at pin 5 can cause nonlinearity with large output voltage swings (very near the supply rails).
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INSIDE THE INA326 The INA326 uses a new, unique internal circuit topology that provides true rail-to-rail input. Unlike other instrumentation amplifiers, it can linearly process inputs up to 20mV below the negative power-supply rail, and 100mV above the positive power-supply rail. Conventional instrumentation amplifier circuits cannot deliver such performance, even if rail-to-rail op amps are used. A1 and A2’s output stages. A2 combines the current in R1 with a mirrored replica of the current from A1.
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APPLICATION CIRCUITS 2 R0 1 R1 6 INA326 VO 5 8 VREF C0 3 R′2 R2 and R′2 are chosen to R2 C2 create a small output offset voltage (e.g., 100mV). Gain is determined by G = 2 (R2 || R′2)/R1 the parallel combination of R2 and R′2. FIGURE 6. Generating Output Offset Voltage. VREF 2 1 INA326 2kΩ RO 100Ω 6 8 5 A/D Converter CO 1µF 3 200kΩ C2 200kΩ G = 2(200kΩ || 200kΩ)/2kΩ = 100 FIGURE 7. Output Referenced to VREF/2.
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+5V 2 7 1 R1 6 INA326 R2 2kΩ IL VO = 2(IL × RS) VO 5 8 3 RO 100Ω CO 1µF C2 R2 R1 RL RS must be chosen so that the input voltage does not exceed 20mV beyond the rail. RS NOTE: Connection point of V− will include ( ) or exclude ( ) quiescent current in the measurement as desired. Output offset required for measurements near zero (see Figure 6). FIGURE 9. Low-Side Current Shunt Measurement. 1nF RF = 100kΩ NOTE: 0.2% accuracy.
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2 + 1 VIN 2kΩ 6 INA326 8 − VO = VIN (100) + VDAC 5 +5V 3 1nF 100kΩ 2 DAC VDAC = 0.075V to 4.925V 7 +15V 1 R1 VD 6 INA326 FIGURE 12. Output Offset Adjustment. NC(1) 5 8 2 4 3 3 OPA277 6 VO 4 (2) VCM 7 −15V +1.8V to +5V R2 C2 +5V Logic 2 9 1 R1 INA327 7 10 3 NOTES: (1) NC denotes No Connection. (2) Typical swing capability −20mV to (+5V + 100mV). 6 Enable 8 4 1nF R2(1) FIGURE 14. Output from Pin 5 to Allow Swing Beyond the Rail.
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VREF = +2.5V +2.5V 2 DAC 7 1 6 INA326 RI = 200kΩ 5 8 4 3 10kΩ −2.5V IOUT = 2 VREF − VDAC 200kΩ 49.9Ω IO 1+ 10kΩ 49.9Ω RL 0.1µF IO = ±5mA with 0.1µA stability. FIGURE 16. Programmable ±5mA Current Source. RI = 1kΩ RF = 100kΩ VI +30V 20kΩ 2 3 +5V 7 OPA551 4 2 IB 2kΩ 6 INA326 5 8 3 −30V 7 1 4 10nF 20kΩ 6 VO = –27V VOS = –100µV at 200mA G=− RF RI = −100V/V Offset of the high- voltage op amp is controlled by the INA326.
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FIGURE 18. Single-Supply PID Temperature Control Loop. INA326, INA327 SBOS222D www.ti.com 17 R6 9.53kΩ R7 1kΩ POT R11 14.3kΩ IN− R9 2kΩ IN+ C6 10µF 2 1 8 3 VS 4 8 VBIAS R8 100kΩ 5 C2 470nF INA326 7 4 V+ V− 0.1µF REF1004- 2.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 11-Apr-2013 (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.
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PACKAGE MATERIALS INFORMATION www.ti.com 26-Jan-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing INA326EA/250 VSSOP DGK INA326EA/2K5 VSSOP INA327EA/250 VSSOP INA327EA/2K5 VSSOP SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 8 250 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 DGK 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 DGS 10 250 180.0 12.4 5.3 3.4 1.4 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 26-Jan-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) INA326EA/250 VSSOP DGK 8 250 366.0 364.0 50.0 INA326EA/2K5 VSSOP DGK 8 2500 366.0 364.0 50.0 INA327EA/250 VSSOP DGS 10 250 210.0 185.0 35.0 INA327EA/2K5 VSSOP DGS 10 2500 367.0 367.0 35.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.