Texas Instruments LMC6494AEMX

Overview

LMC6494AEMX from Texas Instruments (formerly National Semiconductor) is a quad CMOS rail-to-rail input and output operational amplifier designed for single-supply automotive sensor signal conditioning. It operates from 5V to 15V, delivers rail-to-rail output swing within 20 mV of supply rails at 100 kΩ load, features 150 fA input bias current, 82 dB CMRR, and −40°C to +125°C operating temperature range-enabling high-accuracy pressure, oxygen, and temperature sensor front-ends.

For engineers reviewing the LMC6494AEMX datasheet, LMC6494AEMX pinout, LMC6494AEMX application, or LMC6494AEMX equivalent, key selection criteria include ultra-low input current for high-impedance transducer interfacing, guaranteed rail-to-rail operation over full temperature range, CMRR stability across common-mode voltage, and SOIC-14 packaging compatibility with automotive PCB layout constraints.

Technical Context

The LMC6494AEMX employs a proprietary CMOS input stage enabling input common-mode voltage range extending 0.3 V beyond both supply rails-eliminating phase inversion and non-linear errors when sensor signals exceed rail limits. Its output stage delivers true rail-to-rail swing via complementary push-pull architecture, maintaining linearity down to 20 mV from V− and V+ under 100 kΩ load.

It achieves 120 dB open-loop gain and 82 dB CMRR across 0 V to 15 V common-mode range at V+ = 15 V, with PSRR ≥60 dB over 5 V–15 V supply variation. The 1.5 MHz gain-bandwidth product and 1.3 V/µs slew rate support precision DC and low-frequency AC signal amplification in closed-loop configurations up to unity gain.

Key Specifications

Pinout & Package

LMC6494AEMX is housed in a 14-pin SOIC (Small Outline Integrated Circuit) package (NS Package Number M14A), surface-mount compatible with standard reflow profiles and automotive-grade board assembly requirements.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLC27L4CDR and OPA4340UA, the LMC6494AEMX uniquely combines guaranteed rail-to-rail input beyond rails, 150 fA bias current, and −40°C to +125°C qualification - making it irreplaceable for high-precision, high-temperature automotive sensor signal chains where input headroom and leakage immunity are non-negotiable.

Availability

LMC6494AEMX is available at Aetrix Electronics and suitable for automotive pressure sensing, oxygen sensor conditioning, temperature monitoring, and speed detection applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LMC6494AEMX 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

Texas Instruments acquired National Semiconductor in 2011 and maintains full technical and manufacturing continuity for legacy precision analog products including the LMC649x family.

The LMC649x series was engineered specifically for single-supply automotive sensor signal conditioning-prioritizing rail-to-rail operation, ultra-low input current, and wide-temperature reliability over speed or power efficiency.

FAQ

What is the maximum supply voltage for LMC6494AEMX?

The absolute maximum supply voltage (V+ − V−) for LMC6494AEMX is 16 V, with recommended operating range from 2.5 V to 15.5 V. Operation at 15.5 V is validated across −40°C to +125°C, and output swing remains within 20 mV of rails at 100 kΩ load. Exceeding 16 V risks permanent damage per Absolute Maximum Ratings.

Does LMC6494AEMX support true rail-to-rail input beyond the supply rails?

Yes, LMC6494AEMX guarantees rail-to-rail input common-mode voltage range from V− − 0.25 V to V+ + 0.25 V at temperature extremes, enabling direct connection to transducers whose output exceeds supply rails-such as unregulated bridge sensors or thermocouples-without phase inversion or clipping.

What is the input bias current specification for LMC6494AEMX?

The LMC6494AEMX has a typical input bias current of 150 fA and a maximum of 200 pA across −40°C to +125°C. This ultra-low value allows direct interfacing with high-impedance sources like piezoresistive sensors, pH electrodes, and photodiodes without introducing measurable offset voltage errors in precision gain stages.

Can LMC6494AEMX drive capacitive loads directly?

LMC6494AEMX is not optimized for direct capacitive loading; its phase margin degrades with >100 pF loads. For stable operation, use a series resistor (≥100 Ω) between output and capacitive load, or implement the compensated non-inverting configuration shown in Figure 5 of the datasheet-especially critical in anti-aliasing filter applications.

Is LMC6494AEMX qualified for automotive applications?

Yes, LMC6494AEMX is explicitly rated for −40°C to +125°C junction temperature and listed in National Semiconductor's automotive-grade ordering table. Its design targets automotive transducer amplification-including pressure, oxygen, temperature, and speed sensors-with validated CMRR, PSRR, and rail-to-rail performance across this full range.