Analog Devices Inc. LT1168CN8#PBF

Overview

LT1168CN8#PBF from Analog Devices (acquired Linear Technology) is a micropower, laser-trimmed 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 (G=1) across ±2.3V to ±18V supplies - enabling high-accuracy bridge sensor conditioning in battery-powered medical and industrial equipment.

For engineers reviewing the LT1168CN8#PBF datasheet, LT1168CN8#PBF pinout, LT1168CN8#PBF application, or LT1168CN8#PBF equivalent, key selection criteria include gain error (0.4% max at G=10), load capability down to 2kΩ, ESD robustness (13kV HBM), IEC 1000-4-2 Level 4 compliance with two 5kΩ resistors, and 350µA typical supply current for ultra-low-power designs.

Technical Context

The LT1168CN8#PBF implements a three-op-amp topology with laser-trimmed internal 24.7kΩ resistors (R1/R2) and superbeta NPN input transistors (Q1/Q2), enabling precise gain setting via single external RG and achieving <0.3µV/°C input offset drift. Its transconductance-scaling architecture maintains bandwidth stability across gain settings - delivering 400kHz BW at G=1 and 1kHz at G=1000.

Input stage bias currents are held constant via feedback loops (Q1-A1-R1, Q2-A2-R2), ensuring picoampere-level input bias (250pA max) and high common-mode rejection even under mismatched source impedances. The REF pin directly references output to an externally set voltage, with 60kΩ input resistance and ±1.6V headroom from rails.

Key Specifications

Pinout & Package

LT1168CN8#PBF is housed in an 8-pin PDIP (N8) package with 0.3-inch body width and through-hole mounting. Pin spacing is 0.1 inch, compatible with standard PCB layouts and socket-based prototyping.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD620ARZ and INA128UA, the LT1168CN8#PBF offers superior micropower operation (350µA typ), wider supply range (±18V), and certified ESD robustness - making it optimal for battery-powered, high-reliability industrial sensing where long-term stability and ruggedness are mandatory.

Availability

LT1168CN8#PBF is available at Aetrix Electronics and suitable for bridge amplifiers, strain gauge interfaces, and medical instrumentation requiring stable component supply, long-lifecycle support, and traceable sourcing for production programs.

Supply support for LT1168CN8#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 LT1168CN8#PBF belongs to ADI's precision instrumentation amplifier product line, engineered for high-accuracy, low-power sensor signal conditioning in demanding environments where offset drift, noise, and ESD resilience are critical.

FAQ

What is the maximum gain achievable with the LT1168CN8#PBF?

The LT1168CN8#PBF supports a gain range of 1 to 10,000, set by a single external resistor RG using the formula G = 1 + (49.4kΩ/RG). At G=10,000, RG = 4.94Ω (standard 1% value not available; requires precision resistor or parallel combination). The LT1168CN8#PBF maintains specified performance including 20ppm nonlinearity and 0.5% gain error up to G=1000 per datasheet test conditions.

Does the LT1168CN8#PBF require external trimming for offset voltage?

No, the LT1168CN8#PBF is laser-trimmed at wafer level to achieve 40µV max input offset voltage and 0.3µV/°C drift, eliminating the need for external nulling circuits in most applications. Optional trimming is possible via the REF pin using an op-amp buffer circuit (Figure 4 in datasheet), but this is reserved for ultra-high-accuracy systems where residual offset must be reduced below 5µV.

Can the LT1168CN8#PBF drive capacitive loads?

Yes, the LT1168CN8#PBF is designed to remain stable with capacitive loads up to 1000pF in any gain configuration, as verified in datasheet Figure 16 (Overshoot vs Capacitive Load). For loads >1000pF, external isolation (e.g., series resistor + local bypass) is recommended to maintain phase margin and prevent peaking or oscillation in closed-loop systems.

What is the input voltage range for the LT1168CN8#PBF at G=10 and ±15V supplies?

At G=10 and ±15V supplies, the LT1168CN8#PBF input voltage range is –VS + 1.9V to +VS – 1.4V, i.e., –13.1V to +13.6V. This is derived from the datasheet's specified input common-mode range (Table "VCM" under Electrical Characteristics), which decreases slightly with increasing gain due to internal IR drops. The LT1168CN8#PBF maintains full rail-to-rail output swing (±13.6V) within this input range.

Is the LT1168CN8#PBF pin-compatible with the AD620 or INA118?

Yes, the LT1168CN8#PBF is explicitly described in its datasheet as a "pin-for-pin improved second source for the AD620 and INA118", sharing identical 8-pin PDIP/SO footprints and pin assignments (RG, –IN, +IN, –VS, REF, OUTPUT, +VS). However, design validation is required for gain error (0.4% vs AD620's 0.1%), noise (10nV/√Hz vs AD620's 9nV/√Hz), and ESD behavior before drop-in replacement.