Analog Devices Inc. LT1638CDD#PBF

Overview

LT1638CDD#PBF from Analog Devices (formerly Linear Technology) is a dual rail-to-rail input/output operational amplifier in an 8-lead 3mm × 3mm plastic DFN package, featuring Over-The-Top® operation with inputs up to 44V above V–, 1.2MHz gain bandwidth, 0.4V/μs slew rate, and 170μA per amplifier quiescent current. It operates on single or split supplies from 2.5V to 44V and is reverse-battery protected to 18V, enabling use in battery monitoring and high-side sensing circuits.

For engineers reviewing the LT1638CDD#PBF datasheet, LT1638CDD#PBF pinout, LT1638CDD#PBF application, or LT1638CDD#PBF equivalent, key selection criteria include its ±15V-compatible rail-to-rail I/O, 44V common-mode input range beyond V+, 25mA output drive capability, low micropower consumption, and DFN thermal performance (θJA = 43°C/W).

Technical Context

The LT1638CDD#PBF integrates dual NPN/PNP input stages enabling true Over-The-Top operation-inputs can exceed V+ by up to 0.3V while maintaining phase reversal protection and 44V differential/common-mode tolerance. Its internal compensation supports stable unity-gain operation and drives ≥200pF capacitive loads; optional RC compensation extends this to 1000pF.

It delivers rail-to-rail output swing within 20mV of V+ and 3mV of V– at no load, with 25mA minimum sourcing/sinking capability under ±15V supplies. Input offset voltage is 400–1450μV over –40°C to 85°C, and CMRR is 80–98dB across 0V to 44V common-mode range.

Key Specifications

Pinout & Package

LT1638CDD#PBF uses an 8-lead plastic DFN (3mm × 3mm, 0.8mm height) with exposed thermal pad internally connected to V–. The package provides low thermal resistance (θJA = 43°C/W) and space-constrained compatibility for portable and industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual rail-to-rail op amp applications.

Compared with AD8602ARMZ and TSV912IDT, the LT1638CDD#PBF uniquely supports 44V Over-The-Top inputs and reverse-battery survival while consuming <200μA - making it irreplaceable in industrial 24V/48V monitoring and automotive battery management where supply robustness and wide common-mode range are mandatory.

Availability

LT1638CDD#PBF is available at Aetrix Electronics and suitable for battery monitoring systems, high-side current sensing circuits, and micropower active filters requiring stable component supply across extended temperature ranges (–40°C to 85°C) and long production lifecycles.

Supply support for LT1638CDD#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.

The LT1638 product line was designed specifically for micropower, high-voltage-tolerant signal conditioning in harsh environments - targeting battery-powered instrumentation, automotive subsystems, and industrial process control where supply resilience and wide input range are critical.

FAQ

What is the maximum input voltage range supported by the LT1638CDD#PBF?

The LT1638CDD#PBF supports an input common-mode voltage range from –0.4V to 44V relative to V–, including operation with inputs exceeding V+ by up to 0.3V (Over-The-Top®). This is validated across the full –40°C to 85°C operating temperature range and enables direct interfacing with 44V battery buses without external level-shifting components.

Does the LT1638CDD#PBF require external compensation for driving capacitive loads?

The LT1638CDD#PBF is internally compensated and stable driving ≥200pF capacitive loads under all conditions. For loads >200pF up to 1000pF, optional external compensation using a 0.22μF capacitor in series with a 150Ω resistor from output to ground is recommended - a configuration verified in the LT1638/LT1639 datasheet Figure 12.

What is the thermal performance of the LT1638CDD#PBF in its DFN package?

The LT1638CDD#PBF in the 8-lead 3mm × 3mm DFN package has a junction-to-ambient thermal resistance (θJA) of 43°C/W, significantly lower than MSOP (190°C/W) or SO-8 (150°C/W) variants. This enables higher continuous output current in compact layouts, provided the exposed V– pad is soldered to a ≥1cm² copper pour.

Can the LT1638CDD#PBF operate with a single 3.3V supply?

Yes, the LT1638CDD#PBF is fully specified and functional on single supplies from 2.5V to 44V, including 3.3V. At 3.3V, it maintains rail-to-rail input/output swing, 170μA quiescent current, and 1.2MHz GBW - making it suitable for low-voltage portable instrumentation where headroom and power efficiency are critical.

How does the LT1638CDD#PBF handle reverse battery conditions?

Under reverse battery conditions up to –18V, the LT1638CDD#PBF draws <1nA supply current and remains undamaged. This protection is inherent to the architecture and requires no external components - a key differentiator for automotive and industrial field-deployed equipment where wiring errors are common.