LT1097 - Precision Operational Amplifier

Overview

The LT1097 is a high-precision operational amplifier designed to deliver exceptional performance in applications requiring low offset voltage, low noise, and high gain. Manufactured by Linear Technology Corporation (now part of Analog Devices), this component is optimized for precision instrumentation, active filtering, and battery-powered systems. With its ultra-low input offset voltage and drift, the LT1097 is an ideal replacement for older precision op-amps such as the OP-07, OP-77, and AD707, offering superior price-to-performance ratios.

Features

• Ultra-Low Offset Voltage: 50µV maximum ensures high accuracy in precision applications.
• Low Offset Voltage Drift: 1µV/°C maximum minimizes temperature-induced errors.
• Low Bias Current: 250pA maximum reduces input loading effects.
• Low Offset Current: 250pA maximum enhances differential signal accuracy.
• Minimal Current Drift: Bias and offset current drift as low as 4pA/°C.
• Low Power Consumption: Supply current of 560µA maximum, ideal for battery-operated devices.
• Low Noise Performance: 0.5µV_p-p (0.1Hz to 10Hz) and 2.2pA_p-p noise for sensitive signal conditioning.
• High CMRR: 115dB minimum ensures excellent common-mode rejection.
• High Voltage Gain: 117dB minimum for high-precision amplification.
• High PSRR: 114dB minimum minimizes power supply variations' impact.
• Battery-Operated Compatibility: Guaranteed operation on two NiCad batteries.

Applications

The LT1097 is suited for a wide range of precision analog applications, including:

• Replacement for Legacy Precision Op-Amps: Offers improved performance over OP-07, OP-77, OP-97, OP-177, AD707, and LT1001.
• High-Impedance Difference Amplifiers: Ideal for sensor signal conditioning with minimal loading effects.
• Logarithmic Amplifiers: Supports wide dynamic range applications.
• Thermocouple Amplifiers: Low drift and noise ensure accurate temperature measurements.
• Precision Instrumentation: Suitable for medical, industrial, and test equipment requiring high accuracy.
• Active Filters: Works efficiently with small capacitors due to low bias currents.

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_S): ±18V
• Input Voltage Range: ±V_S
• Operating Temperature Range: -40°C to +85°C
• Storage Temperature Range: -65°C to +150°C

Key Performance Specifications

• Input Offset Voltage (V_OS): 50µV (max)
• Input Offset Voltage Drift: 1µV/°C (max)
• Input Bias Current (I_B): 250pA (max)
• Input Offset Current (I_OS): 250pA (max)
• Bias/Offset Current Drift: 4pA/°C (max)
• Supply Current (I_S): 560µA (max)
• Noise (0.1Hz to 10Hz): 0.5µV_p-p, 2.2pA_p-p
• Common-Mode Rejection Ratio (CMRR): 115dB (min)
• Open-Loop Voltage Gain (A_VOL): 117dB (min)
• Power Supply Rejection Ratio (PSRR): 114dB (min)

Package Information

The LT1097 is available in multiple package options to accommodate various PCB layouts and thermal requirements. Common packages include:

• 8-Pin PDIP (Plastic Dual In-Line Package): Industry-standard through-hole mounting.
• 8-Pin SOIC (Small Outline Integrated Circuit): Surface-mount package for space-constrained designs.
• TO-99 Metal Can: Hermetically sealed package for high-reliability applications.

Pin Configuration (8-Pin PDIP/SOIC)

• Pin 1: Offset Null
• Pin 2: Inverting Input (-IN)
• Pin 3: Non-Inverting Input (+IN)
• Pin 4: Negative Supply (V_-)
• Pin 5: Offset Null
• Pin 6: Output (OUT)
• Pin 7: Positive Supply (V₊)
• Pin 8: NC (No Connection)

Typical Application Circuit

The LT1097 is commonly used in precision amplification circuits. Below is a simplified example of a thermocouple amplifier configuration:

• Input Stage: Thermocouple connected to +IN and -IN via high-precision resistors.
• Gain Setting: Feedback resistor network sets amplification factor.
• Power Supply: Dual ±2.4V (two NiCad batteries) or single-supply with biasing.
• Output Filtering: Optional RC filter to reduce high-frequency noise.

Conclusion

The LT1097 is a versatile, high-precision operational amplifier that excels in applications demanding low noise, low drift, and high gain. Its robust electrical characteristics and flexible packaging options make it suitable for a broad range of industrial, medical, and instrumentation applications. By replacing older-generation op-amps, the LT1097 provides designers with improved performance while maintaining cost efficiency.