Analog Devices Inc. LT1168IS8#PBF

Overview

LT1168IS8#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 90dB CMRR at G=1 while operating from ±2.3V to ±18V supplies with just 530µA max supply current. It is widely used in strain gauge, thermocouple, and bridge amplifier circuits for industrial sensor signal conditioning.

For engineers reviewing the LT1168IS8#PBF datasheet, LT1168IS8#PBF pinout, LT1168IS8#PBF application, or LT1168IS8#PBF equivalent, key selection criteria include gain programmability via single RG resistor, guaranteed performance over –40°C to +85°C, laser-trimmed input offset drift of 0.3µV/°C, and IEC 1000-4-2 Level 4 ESD compliance with two external 5kΩ resistors.

Technical Context

The LT1168IS8#PBF implements a three-op-amp instrumentation architecture with laser-trimmed internal 24.7kΩ resistors (R1/R2) and superbeta NPN input transistors (Q1/Q2), enabling precise gain setting via external RG and picoampere-level input bias currents (250pA max). Its transconductance-based preamp stage scales with programmed gain, maintaining bandwidth stability and minimizing gain-related errors.

It features a dedicated REF pin (Pin 5) that defines the output's reference level, with output voltage referenced as V_OUT = G·(V_+IN – V_–IN) + V_REF. Input common-mode range extends to within 1.9V of –V_S and 1.4V of +V_S at G=1, degrading predictably with gain per the IR drop across internal gain-setting resistors.

Key Specifications

Pinout & Package

LT1168IS8#PBF is housed in an 8-lead plastic SO package (S8), measuring 5.0mm × 4.0mm × 1.5mm with standard SOIC footprint and gull-wing leads. Thermal resistance θ_JA = 190°C/W enables operation up to 85°C ambient without heatsinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD620ARZ and INA128UA, the LT1168IS8#PBF provides superior micropower operation (530µA vs ≥1.3mA), lower 0.1Hz–10Hz noise (0.28µV_P-P), and factory-validated IEC 1000-4-2 Level 4 compliance-making it the preferred choice for portable, certified, and long-life sensor systems.

Availability

LT1168IS8#PBF is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, portable medical devices, and battery-powered test equipment requiring stable component supply and long-term lifecycle support.

Supply support for LT1168IS8#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 technologies, serving industrial, automotive, communications, and healthcare markets.

The LT1168 product line was originally developed by Linear Technology (acquired by ADI in 2017) to address demand for low-power, high-accuracy instrumentation amplifiers in space-constrained and energy-sensitive sensor interfaces.

FAQ

What is the maximum gain achievable with LT1168IS8#PBF and how is it set?

The LT1168IS8#PBF supports gains from 1 to 10,000, set by a single external resistor RG connected between Pins 1 and 8. The gain equation is G = 1 + (49.4kΩ/RG); for G = 10,000, RG = 4.94Ω. At G = 1000, LT1168IS8#PBF maintains 25ppm gain nonlinearity with 2kΩ load, verified per datasheet Figure 1.

Does LT1168IS8#PBF support single-supply operation?

Yes, LT1168IS8#PBF operates from single supplies down to +4.6V (equivalent to ±2.3V), with input common-mode range extending to within 1.9V of the negative rail and 1.4V of the positive rail at G = 1. For optimal single-supply performance, the REF pin must be biased above the negative rail, and one input held ≥2.5V above ground-as demonstrated in the "Single Supply Pressure Monitor" application circuit.

What is the guaranteed temperature range for LT1168IS8#PBF?

The LT1168IS8#PBF is rated for operation from –40°C to +85°C and is fully specified and tested across this range. Unlike the 'C' grade variants, the 'I' grade (denoted by 'I' in LT1168I and 'IS8' package) guarantees all electrical parameters-including gain error (0.6% max at G=10), CMRR (86dB min at G=1), and supply current (650µA max)-over the full industrial temperature span.

How does LT1168IS8#PBF achieve its low input bias current of 250pA max?

LT1168IS8#PBF achieves ultra-low input bias current using superbeta NPN input transistors (Q1/Q2) fabricated in a proprietary process that minimizes base current. This, combined with laser-trimmed collector current matching, yields 250pA max input bias current and 300pA max input offset current at 25°C-critical for interfacing with high-impedance pH electrodes and piezoelectric sensors without added offset error.

Can LT1168IS8#PBF drive ADC inputs directly?

Yes, LT1168IS8#PBF can drive SAR and delta-sigma ADC inputs directly due to its ability to stabilize with up to 1000pF capacitive load in any gain configuration. Its output voltage swing (–V_S + 1.6V to +V_S – 1.5V at G ≥ 5) and low 0.28µV_P-P 0.1Hz–10Hz noise ensure clean sampling without settling-time penalties or external buffer stages.