Analog Devices Inc. LT1168AIN8#PBF

Overview

LT1168AIN8#PBF from Analog Devices (acquired Linear Technology) is a micropower, precision instrumentation amplifier requiring only one external resistor to set gains from 1 to 10,000. It delivers 10nV/√Hz input voltage noise at 1kHz, 40µV max input offset voltage, and 0.4% max gain error at G=10 - all while consuming just 530µA max supply current across ±2.3V to ±18V supplies. It is widely deployed in strain gauge and thermocouple amplification within industrial sensor interfaces.

For engineers reviewing the LT1168AIN8#PBF datasheet, LT1168AIN8#PBF pinout, LT1168AIN8#PBF application, or LT1168AIN8#PBF equivalent, this page provides verified circuit role, validated pin functions, confirmed load-drive capability (2kΩ min), ESD robustness (13kV HBM), and precise alternative selection guidance for medical, battery-powered, and high-accuracy measurement systems.

Technical Context

The LT1168AIN8#PBF implements a laser-trimmed, three-op-amp instrumentation architecture with superbeta NPN input transistors enabling 250pA max input bias current and 200GΩ min input resistance. Its gain-setting topology uses a single external resistor (RG) across Pins 1 and 8, where G = 1 + (49.4kΩ/RG), ensuring predictable scaling without matching networks.

It features dual-stage trimming: input offset voltage (40µV max) and drift (0.3µV/°C max) are laser-adjusted at wafer level, while CMRR (90dB min at G=1) and PSRR (103dB min at G=1) are stabilized via matched internal resistors (24.7kΩ) and feedback loops. The output stage drives capacitive loads up to 1000pF without instability across all gains.

Key Specifications

Pinout & Package

LT1168AIN8#PBF is housed in an 8-pin PDIP (N8) package with through-hole mounting and 0.3-inch width. Pin spacing is 0.1 inch, compatible with standard prototyping and industrial PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar instrumentation amplifier applications.

Compared with AD620ARZ and INA128UA, the LT1168AIN8#PBF uniquely balances ultra-low power (530µA), industry-leading ESD hardness (13kV), and 10nV/√Hz noise - making it the optimal choice for portable, high-reliability sensor nodes where battery life and ruggedness are co-primary constraints.

Availability

LT1168AIN8#PBF is available at Aetrix Electronics and suitable for strain gauge amplification, thermocouple interfacing, and portable medical instrumentation requiring stable component supply across extended production lifecycles.

Supply support for LT1168AIN8#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LT1168 series was developed by Linear Technology (acquired by ADI in 2017) specifically for precision, low-power sensor signal conditioning - targeting applications where micropower operation, laser-trimmed accuracy, and robust ESD tolerance are simultaneously required.

FAQ

What is the maximum capacitive load the LT1168AIN8#PBF can drive without oscillation?

The LT1168AIN8#PBF is specified to remain stable with capacitive loads up to 1000pF across all gain configurations. This is verified in the datasheet's "Overshoot vs Capacitive Load" plot (Figure 1168 G16), where phase margin remains sufficient even at G=1 with 10,000pF - though 1000pF is the guaranteed limit for production designs. For loads exceeding 1000pF, an external isolation resistor (e.g., 10–50Ω) in series with the output is recommended. The LT1168AIN8#PBF achieves this stability via internal compensation optimized for its three-op-amp topology.

Does the LT1168AIN8#PBF support true single-supply operation (e.g., +5V and GND)?

Yes - the LT1168AIN8#PBF supports single-supply operation from +4.6V to +36V (i.e., ±2.3V to ±18V dual equivalent). When operated from +5V/GND, the input common-mode range extends from +1.9V to +3.6V (per datasheet Table "Input Voltage Range"), and the output swings from +1.1V to +3.8V into 10kΩ. To ensure proper biasing, the REF pin must be set to a mid-supply voltage (e.g., +2.5V) using a low-impedance source; the LT1168AIN8#PBF itself does not generate this reference. This configuration is validated in the "Single Supply Pressure Monitor" application circuit (Figure 1168 TA01a).

What is the minimum load resistance the LT1168AIN8#PBF can drive while maintaining 20ppm gain nonlinearity?

The LT1168AIN8#PBF guarantees ≤20ppm gain nonlinearity at G=10 with a 2kΩ load, as explicitly stated in the "Gain Nonlinearity" section of the datasheet (VO = ±10V, G = 10, RL = 2k). This is a key differentiator versus prior monolithic instrumentation amplifiers, which degraded significantly below 10kΩ. Driving lower loads (e.g., 600Ω) increases nonlinearity beyond 20ppm and may reduce output swing - the device remains functional but violates the precision specification. For 2kΩ loads, the LT1168AIN8#PBF delivers full accuracy without external buffering.

How does the LT1168AIN8#PBF achieve 13kV HBM ESD protection without external components?

The LT1168AIN8#PBF integrates proprietary input protection structures - including large-area, low-leakage silicon-controlled rectifiers (SCRs) and current-limiting resistors - directly into its input transistor cells. These are process-optimized during Linear Technology's fabrication and validated per JEDEC JS-001. Unlike standard op-amps requiring external 10kΩ series resistors and TVS diodes, the LT1168AIN8#PBF passes IEC 1000-4-2 Level 4 (±15kV contact) when used with two external 5kΩ resistors (as documented in the "Features" list), confirming system-level robustness. This eliminates BOM cost and board space for discrete protection in sensor front-ends.

Is the LT1168AIN8#PBF pin-compatible with the AD620 and INA118 as claimed in the datasheet?

Yes - the LT1168AIN8#PBF is explicitly designed as a pin-for-pin improved second source for both the AD620 and INA118 in 8-pin SO and PDIP packages. Pin mapping (RG, –IN, +IN, –VS, REF, OUTPUT, +VS, RG) matches identically, and electrical characteristics exceed both predecessors: lower supply current (530µA vs 1.3mA for AD620), lower noise (10nV/√Hz vs 12nV/√Hz), and higher ESD rating (13kV vs unspecified for AD620). No PCB changes are required when upgrading from AD620AN/AD620AR or INA118P/INA118PA to LT1168AIN8#PBF.