Analog Devices Inc. LT1008IN8

Overview

LT1008IN8 from Analog Devices (formerly Linear Technology) is a precision operational amplifier designed for ultra-low-input-bias-current, microvolt-offset, low-noise analog signal conditioning in demanding instrumentation and metrology systems. It delivers guaranteed 120μV max input offset voltage, 600pA max input bias current over –40°C to 85°C, 0.5μV_P-P 0.1Hz–10Hz noise, 114dB min CMRR/PSRR, and 600μA max supply current in an 8-lead PDIP package.

For engineers reviewing the LT1008IN8 datasheet, LT1008IN8 pinout, LT1008IN8 application, or LT1008IN8 equivalent, this page provides verified specifications, validated pin functions, real-world use cases in charge integration and thermocouple amplification, and two confirmed alternative op amps with documented performance trade-offs.

Technical Context

The LT1008IN8 employs a proprietary JFET-input stage enabling picoampere-level bias currents across its full –40°C to 85°C operating range. Its external frequency compensation via dual COMP pins (Pin 1 and Pin 5) allows flexible bandwidth/slew rate tuning - e.g., 0.1 V/μs with 30pF, up to 4 V/μs at high closed-loop gains without compensation.

It achieves microvolt-level DC precision through laser-trimmed input offset and low-drift architecture (1.5μV/°C max drift), while maintaining 200 V/mV minimum large-signal voltage gain into 10kΩ loads and ±13V output swing on ±15V supplies - critical for high-resolution sensor front-ends and reference buffers.

Key Specifications

Pinout & Package

LT1008IN8 is housed in an 8-lead plastic dual in-line package (PDIP), N8 package per Linear Technology drawing #05-08-1510, with 0.300-inch body width and 0.100-inch lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT1008IN8, LT1012CN8 trades external compensation flexibility for lower offset, while OPA2189IDR replaces JFET input with zero-drift topology - offering better long-term stability but introducing switching artifacts incompatible with charge integration.

Availability

LT1008IN8 is available at Aetrix Electronics and suitable for precision instrumentation, metrology-grade voltage references, and low-drift sensor signal conditioning requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LT1008IN8 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 product support, documentation, and manufacturing continuity for legacy Linear precision op amps.

The LT1008IN8 belongs to Linear's universal precision op amp family, engineered specifically for applications demanding simultaneous picoampere bias current, microvolt offset, and low 0.1Hz–10Hz noise - such as calibration equipment and scientific measurement systems.

FAQ

What is the maximum guaranteed input bias current for LT1008IN8 over its full operating temperature range?

The LT1008IN8 guarantees ≤600pA maximum input bias current across its specified –40°C to 85°C operating temperature range. This value is explicitly stated in the Electrical Characteristics table for the LT1008I grade under "Input Bias Current" with conditions TA = –40°C to 85°C. At 25°C, the limit is tighter at 100pA max, but system design must use the worst-case 600pA figure for thermal margining in the LT1008IN8.

Can LT1008IN8 be used as a direct replacement for LM308A in existing designs?

Yes, the LT1008IN8 is pin-compatible with the LM308A and can be plugged directly into the same socket. Its external compensation architecture matches the LM308A's, allowing identical CF capacitor values. However, the LT1008IN8 delivers superior DC specs - 120μV max offset vs. 1500μV for LM308A, and 600pA max bias vs. 150nA - making it a functional upgrade without layout changes.

Does LT1008IN8 require external frequency compensation in all configurations?

No. The LT1008IN8 does not require external compensation when configured for closed-loop gains ≥200. In such high-gain configurations, its internal architecture provides sufficient phase margin, and omitting the compensation capacitor increases slew rate to 4V/μs. For gains below 200, external compensation via Pins 1 and 5 is mandatory to ensure stability - typically using 30pF for unity-gain stable behavior.

What is the purpose of Pin 8 (NC) on the LT1008IN8, and how should it be handled on the PCB?

Pin 8 on the LT1008IN8 is a No-Connect terminal - it is internally unconnected and serves no electrical function. It must remain unconnected on the PCB: do not tie it to ground, supply, or any other net. Leaving it floating prevents unintended coupling or parasitic effects. This is explicitly confirmed in the LT1008 datasheet pin description table and schematic diagrams.

How does the LT1008IN8 achieve low 0.1Hz–10Hz noise while maintaining picoampere input bias current?

The LT1008IN8 achieves 0.5μV_P-P 0.1Hz–10Hz noise through a combination of JFET input stage optimization and proprietary die-level filtering that suppresses 1/f noise without increasing gate leakage. Its picoampere bias is maintained by using matched, low-leakage JFETs with guard-ring isolation and surface passivation - decoupling noise reduction techniques from input current mechanisms, unlike bipolar-input op amps where noise and bias are inherently linked.