Analog Devices Inc. LT1639CN#PBF

Overview

LT1639CN#PBF from Analog Devices (formerly Linear Technology) is a quad rail-to-rail input and output operational amplifier with Over-The-Top® capability, enabling operation with inputs up to 44V above the negative supply or above V+. It delivers 1.2MHz gain bandwidth, 0.4V/µs slew rate, and draws only 170µA per amplifier at 2.5V–44V total supply. Used in battery monitoring and supply current sensing where high-voltage common-mode tolerance and micropower operation are critical.

For engineers reviewing the LT1639CN#PBF datasheet, LT1639CN#PBF pinout, LT1639CN#PBF application, or LT1639CN#PBF equivalent, key selection criteria include its 44V input voltage range beyond V+, reverse-battery protection to 18V, rail-to-rail I/O swing, 25mA output drive, and guaranteed performance over –40°C to +85°C in 14-pin PDIP packaging.

Technical Context

The LT1639CN#PBF integrates dual NPN/PNP input stages enabling true Over-The-Top operation-inputs function reliably at voltages exceeding V+ by up to 44V while maintaining phase reversal protection and ±25mA differential input tolerance. Its internal compensation supports stable unity-gain operation and drives ≥200pF capacitive loads without external compensation.

Each of the four amplifiers features independent reverse-battery protection (≤1nA current draw at –18V), no supply sequencing requirements, and operates on single supplies as low as 2.5V or split supplies up to ±22V. Input bias current varies with common-mode voltage due to dual-input-stage architecture, ranging from –20nA (PNP-active) to +40nA (NPN-active) near V+.

Key Specifications

Pinout & Package

LT1639CN#PBF is housed in a 14-lead plastic PDIP package (N package) with JEDEC standard footprint, 0.300" wide body, and through-hole mounting. Thermal resistance θ_JA = 130°C/W. Underside has no exposed pad; leads are tin-lead (Pb-free finish per #PBF suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLV2464IDR and AD8604ARUZ, the LT1639CN#PBF uniquely supports 44V Over-The-Top inputs and reverse-battery survival - making it irreplaceable in unregulated or fault-prone power environments despite its lower speed and higher offset voltage.

Availability

LT1639CN#PBF is available at Aetrix Electronics and suitable for battery monitoring, supply current sensing, and sensor conditioning requiring stable component supply across industrial temperature ranges and long-lifecycle programs.

Supply support for LT1639CN#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 LT1639CN#PBF belongs to Linear Technology's legacy precision op amp product line, engineered specifically for micropower, high-voltage common-mode, and ruggedized industrial applications where reliability under electrical stress is non-negotiable.

FAQ

What is the maximum input voltage the LT1639CN#PBF can tolerate relative to V–?

The LT1639CN#PBF supports an input voltage range of –0.4V to 44V relative to V–, meaning either input can be as high as 44V above the negative supply rail regardless of V+ value. This Over-The-Top® capability is confirmed in the Absolute Maximum Ratings table and Typical Applications section of the datasheet, enabling direct interface to high-voltage buses without attenuation.

Does the LT1639CN#PBF require external compensation for driving capacitive loads?

The LT1639CN#PBF is internally compensated to drive ≥200pF capacitively without oscillation. For loads >200pF up to 1000pF, optional external compensation - a 0.22µF capacitor in series with a 150Ω resistor from output to ground - is recommended per the Applications Information section. This maintains stability across all output currents and supply voltages.

Can the LT1639CN#PBF operate with a single 3.3V supply?

Yes, the LT1639CN#PBF operates on total supply voltages from 2.5V to 44V, including single 3.3V (V+ = 3.3V, V– = 0V). At 3.3V, it delivers rail-to-rail input/output swing, 1.2MHz GBW, and 170µA per amplifier quiescent current. Electrical Characteristics tables explicitly specify parameters at VS = 3V, confirming full functionality.

What is the thermal performance of the LT1639CN#PBF in the 14-lead PDIP package?

The LT1639CN#PBF in the 14-lead PDIP (N package) has a junction-to-ambient thermal resistance θ_JA of 130°C/W, as documented in the Pin Configuration diagram. With 4 × 170µA supply current and moderate output loading, junction temperature rise remains minimal - enabling reliable operation up to +85°C ambient without heatsinking under typical conditions.

How does the LT1639CN#PBF handle reverse battery connection?

When subjected to reverse supply voltage up to –18V, the LT1639CN#PBF draws less than 1nA of current and sustains no damage. This reverse-battery protection is intrinsic to the input stage design and verified in the Absolute Maximum Ratings and Applications Information sections. It eliminates need for external blocking diodes in automotive and portable equipment.