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INA131

Precision G = 100

INSTRUMENTATION AMPLIFIER

DESCRIPTION

The INA131 is a low cost, general purpose G = 100

instrumentation amplifier offering excellent accuracy.

Its 3-op amp design and small size make it ideal for

a wide range of applications.

On-chip laser trimmed resistors accurately set a fixed

gain of 100. The INA131 is laser trimmed to achieve

very low offset voltage (50µV max), drift (0.25µV/°C

max), and high CMR (110dB min). Internal input

protection can withstand up to ±40V inputs without

damage.

The INA131 is available in a 8-pin plastic DIP. They

are specified over the –40°C to +85°C temperature

range.

FEATURES

● LOW OFFSET VOLTAGE: 50µV max

● LOW DRIFT: 0.25µV/°C max

● LOW INPUT BIAS CURRENT: 2nA max

● HIGH COMMON-MODE REJECTION:

110dB min

● INPUT OVERVOLTAGE PROTECTION:

±40V

● WIDE SUPPLY RANGE: ±2.25 to ±18V

● LOW QUIESCENT CURRENT: 3mA

● 8-PIN PLASTIC DIP

APPLICATIONS

● BRIDGE AMPLIFIER

● THERMOCOUPLE AMPLIFIER

● RTD SENSOR AMPLIFIER

● MEDICAL INSTRUMENTATION

● DATA ACQUISITION

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/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132

Over-Voltage

Protection

25kΩ5kΩ

25kΩ

25kΩ5kΩ

V+

V–

INA131

DIP

Ref

= 100 (V

– V

)

–

+–

2.63kΩ

Over-Voltage

Protection

INA131

1992 Burr-Brown Corporation PDS-1144E Printed in U.S.A. March, 1998

SBOS016

Summary of content (11 pages)

PAGE 1
® INA131 INA 131 Precision G = 100 INSTRUMENTATION AMPLIFIER FEATURES DESCRIPTION ● LOW OFFSET VOLTAGE: 50µV max ● LOW DRIFT: 0.25µV/°C max The INA131 is a low cost, general purpose G = 100 instrumentation amplifier offering excellent accuracy. Its 3-op amp design and small size make it ideal for a wide range of applications. ● LOW INPUT BIAS CURRENT: 2nA max ● HIGH COMMON-MODE REJECTION: 110dB min ● INPUT OVERVOLTAGE PROTECTION: ±40V ● WIDE SUPPLY RANGE: ±2.
PAGE 2
SPECIFICATIONS At TA = +25°C, VS = ±15V, RL = 2kΩ, unless otherwise noted. INA131BP PARAMETER CONDITIONS INPUT Offset Voltage, RTI Initial vs Temperature vs Power Supply Long-Term Stability Impedance, Differential Common-Mode Input Common-Mode Range Safe Input Voltage Common-Mode Rejection TYP MAX ±50 ±0.25 3 ±11 ±10 ±0.1 0.5 0.2 1010 || 6 1010 || 6 ±13.5 110 120 TA = +25°C TA = TMIN to TMAX VS = ±2.25V to ±18V VCM = ±10V, ∆RS = 1kΩ INA131AP MIN MIN TYP MAX UNITS ±125 ±1 ✻ ✻ ±25 ±0.
PAGE 3
ABSOLUTE MAXIMUM RATINGS(1) PIN CONFIGURATION Top View P-Package/8-Pin DIP RG 1 8 RG V –IN 2 7 V+ V +IN 3 6 VO V– 4 5 Ref Supply Voltage .................................................................................. ±18V Input Voltage Range .......................................................................... ±40V Output Short Circuit (to ground) .............................................. Continuous Operating Temperature ..................................................
PAGE 4
TYPICAL PERFORMANCE CURVES At 25°C, VS = ±15V, unless otherwise noted.
PAGE 5
TYPICAL PERFORMANCE CURVES (CONT) At 25°C, VS = ±15V, unless otherwise noted. INPUT BIAS CURRENT vs INPUT VOLTAGE 2 3 2 Input Bias Current (mA) Input Bias and Input Offset Current (nA) INPUT BIAS AND INPUT OFFSET CURRENT vs TEMPERATURE 1 ±IB 0 IOS –1 1 0 Common-Mode (|IB1| + |IB2|) Differential Mode –1 –2 –2 –40 –15 10 35 60 –3 –45 85 –30 Temperature (°C) MAXIMUM OUTPUT SWING vs FREQUENCY 0 15 30 45 SLEW RATE vs TEMPERATURE 32 1.2 28 1.
PAGE 6
TYPICAL PERFORMANCE CURVES (CONT) At 25°C, VS = ±15V, unless otherwise noted. POSITIVE SIGNAL SWING vs TEMPERATUE (RL = 2kΩ) 120 2.5 100 2.4 80 Power Dissipation 2.3 60 Quiescent Current 2.2 40 2.1 20 2.0 0 ±3 ±6 ±9 ±12 16 12 VS = ±11.4V 10 8 6 4 VS = ±2.25V 2 0 ±18 ±15 VS = ±15V 14 Output Voltage (V) 2.
PAGE 7
device. Absolute accuracy of the internal values is ±40%. The nominal gain with an external RG resistor can be calculated by: APPLICATION INFORMATION Figure 1 shows the basic connections required for operation of the INA131. Applications with noisy or high impedance power supplies may require decoupling capacitors close to the device pins as shown. G = 100 + 250 kΩ RG The output is referred to the output reference (Ref) terminal which is normally grounded.
PAGE 8
OFFSET TRIMMING The INA131 is laser trimmed for very low offset voltage and drift. Most applications require no external offset adjustment. Figure 2 shows an optional circuit for trimming the output offset voltage. The voltage applied to Ref terminal is summed at the output. Low impedance must be maintained at this node to assure good common-mode rejection. This is achieved by buffering trim voltage with an op amp as shown. Microphone, Hydrophone etc.
PAGE 9
– VIN 1MΩ 1MΩ + VIN VO INA131 Ref Shield is driven at the common-mode potential. 100Ω Common-mode resistors have approximately 0.1% effect on gain. OPA602 FIGURE 4. Shield Driver Circuit. V+ V+ REF200 100µA Equal line resistance here creates a small common-mode voltage which is rejected by INA131. 1 RTD VO INA131 2 Ref RZ 3 VO = 0V at RRTD = RZ Resistance in this line causes a small common-mode voltage which is rejected by INA131. FIGURE 5. RTD Temperature Measurement Circuit. V+ 2 10.
PAGE 10
+10V – VIN R IO = 100 • VIN R INA131 + Ref Bridge IB VO INA131 A1 Ref IO Load FIGURE 7. Bridge Transducer Amplifier. – VIN + ±1.5nA 1pA 75fA FIGURE 9. Differential Voltage to Current Converter. C1 0.1µF OPA602 R1 1MΩ f–3dB = 1 2πR1C1 = 1.59Hz FIGURE 8. AC-Coupled Instrumentation Amplifier.
PAGE 11
IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete.