Analog Devices Inc. LT1673IS8#PBF

Overview

LT1673IS8#PBF from Analog Devices (formerly Linear Technology) is a dual-channel, ultralow-power, precision rail-to-rail input and output operational amplifier with Over-The-Top™ input capability. It delivers 2 µA max supply current per amplifier, 375 µV max input offset voltage, and 12 kHz gain bandwidth product across a 2.2 V to 36 V supply range. It is used in battery-powered sensor signal conditioning where input signals exceed the positive rail.

For engineers reviewing the LT1673IS8#PBF datasheet, LT1673IS8#PBF pinout, LT1673IS8#PBF application, or LT1673IS8#PBF equivalent, key selection criteria include micropower operation under ±15 V or single 5 V supply, reverse-battery protection to –18 V, rail-to-rail I/O swing, and guaranteed performance over –40°C to 85°C.

Technical Context

The LT1673IS8#PBF implements a three-stage architecture: a rail-to-rail input stage with dual differential pairs enabling Over-The-Top operation (inputs up to V+ + 0.3 V), a folded-cascode second stage for high open-loop gain (≥100 V/mV), and a rail-to-rail common-emitter output stage delivering ±500 µA load current. Its decompensated design requires minimum closed-loop gain of 5 for stability.

It features 90 dB PSRR and CMRR at low frequencies, 0.4 µV/°C typical input offset drift, and input bias current as low as 250 pA - enabling use with >1 MΩ source impedances without significant error. The device remains functional during reverse-battery conditions (<100 nA quiescent current).

Key Specifications

Pinout & Package

LT1673IS8#PBF is housed in an 8-lead plastic SOIC (S8) package, 3.9 mm × 4.9 mm, 1.27 mm pitch, JEDEC MS-012 compliant. Thermal resistance θ_JA = 190°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision micropower op amp applications.

Compared with LTC1495CS8#PBF and LT1782CS5#TRMPBF, the LT1673IS8#PBF uniquely combines Over-The-Top input operation, sub-2 µA quiescent current, and dual-channel integration - making it irreplaceable for high-side battery monitoring and ultra-low-power sensor front-ends requiring AV ≥ 5.

Availability

LT1673IS8#PBF is available at Aetrix Electronics and suitable for battery-powered instrumentation, remote sensor amplifiers, and micropower filter applications requiring stable component supply and long-term industrial temperature support.

Supply support for LT1673IS8#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for legacy Linear op amp families.

The LT167x family was designed specifically for ultralow-power, high-precision signal conditioning in harsh environments - emphasizing Over-The-Top input operation, reverse-battery survivability, and guaranteed –40°C to +85°C performance without derating.

FAQ

What is the minimum supply voltage required for stable operation of the LT1673IS8#PBF?

The LT1673IS8#PBF operates down to 2.2 V (minimum specified), with guaranteed functionality at 2.1 V under typical conditions. At 2.2 V, all key specifications - including 375 µV max input offset voltage, 12 kHz GBW, and rail-to-rail output swing - remain valid across the full –40°C to +85°C temperature range. Below 2.2 V, parameters such as open-loop gain and CMRR degrade progressively.

Can the LT1673IS8#PBF drive capacitive loads, and what is the maximum recommended value?

Yes, the LT1673IS8#PBF can drive capacitive loads, but stability depends on output voltage and gain. With output biased at mid-supply and AV = 5, it remains stable with ≤100 pF. If the output operates within 100 mV of V+, allowable capacitance drops to <500 pF at 5 V supply and <100 pF at 30 V supply. For loads >100 pF, a series resistor (e.g., 10–50 Ω) between op amp output and capacitor is recommended to isolate the pole.

Does the LT1673IS8#PBF support true single-supply operation with inputs extending below ground?

Yes. The LT1673IS8#PBF supports true single-supply operation with input common-mode range from –0.3 V to 36 V. Inputs may be taken 300 mV below V– (e.g., –0.3 V with V– = 0 V) without damage, provided input current is limited to <10 mA. However, phase reversal is not guaranteed below –0.3 V, and supply current increases - so operation below this point should be avoided in precision applications.

How does the Over-The-Top™ input feature work in the LT1673IS8#PBF, and what is its practical voltage limit?

The Over-The-Top™ input uses a dual-differential-pair architecture that activates a second input stage when common-mode voltage exceeds V+ – 0.8 V. This allows inputs to operate up to V+ + 0.3 V (typical) without clipping or phase reversal. In practice, the LT1673IS8#PBF reliably accepts inputs up to V+ + 0.25 V across –40°C to +85°C, enabling direct connection to unregulated battery rails in portable equipment.

Is the LT1673IS8#PBF pin-compatible with other dual op amps in SO-8 packages, such as the LM358 or MCP602?

No. The LT1673IS8#PBF uses the industry-standard dual op amp pinout (OUT A, –IN A, +IN A, V–, V+, OUT B, –IN B, +IN B), which matches LM358, TL072, and MCP602. However, due to its decompensated design, it is not unity-gain stable - unlike those parts. Using LT1673IS8#PBF in circuits designed for LM358 without verifying gain ≥5 will result in oscillation. Electrical compatibility requires circuit redesign, not just pin replacement.