Texas Instruments LMC6494BEM

Overview

LMC6494BEM 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, 120 dB open-loop gain, and −40°C to +125°C operating temperature range-enabling high-accuracy transducer amplification in engine control units.

For engineers reviewing the LMC6494BEM datasheet, LMC6494BEM pinout, LMC6494BEM application, or LMC6494BEM equivalent, this page provides verified technical context, package mapping, real-world use scenarios, and validated alternative options for pressure, oxygen, temperature, and speed sensor front-ends requiring ultra-low input current and extended temperature stability.

Technical Context

The LMC6494BEM employs a proprietary CMOS input stage enabling rail-to-rail common-mode voltage range extending beyond both supply rails-eliminating phase inversion and non-linear errors when input signals exceed V− or V+. Its output stage delivers true rail-to-rail swing with sourcing/sinking capability up to ±30 mA, supported by 82 dB CMRR and PSRR across 0–15 V common-mode range.

It integrates ultra-low input current (150 fA typical), low offset voltage drift (1.0 µV/°C), and 1.5 MHz gain-bandwidth product at 15 V supply-optimized for DC-coupled, high-impedance sensor interfaces where leakage-induced error must be minimized and thermal drift tightly controlled over automotive ambient conditions.

Key Specifications

Pinout & Package

LMC6494BEM is housed in a 14-pin SOIC (Small Outline Integrated Circuit) surface-mount package (NS Package Number M14A), measuring 8.65 mm × 3.91 mm × 1.75 mm, with standard 1.27 mm pitch and gull-wing leads. Thermal resistance θJA is 118°C/W on JEDEC-standard 2-layer board.

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 LMC6494BEM uniquely balances ultra-low input current (150 fA), automotive-grade temperature range, and rail-to-rail input/output in a single quad package-making it the optimal choice for DC-coupled, high-impedance transducer interfaces where leakage-induced offset dominates error budget.

Availability

LMC6494BEM is available at Aetrix Electronics and suitable for automotive engine control, exhaust aftertreatment, and chassis electronics requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LMC6494BEM 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 high-reliability analog products.

The LMC6494BEM belongs to TI's precision automotive op-amp portfolio, engineered specifically for sensor signal conditioning in harsh-temperature environments where rail-to-rail operation, ultra-low input current, and high CMRR are mandatory.

FAQ

What is the maximum supply voltage for LMC6494BEM?

The absolute maximum supply voltage (V+ − V−) for LMC6494BEM is 16 V, with recommended operating range from 5 V to 15 V. Operation at 15.5 V is permitted per datasheet Operating Conditions, but sustained use above 15 V may reduce long-term reliability-especially when output is shorted. The LMC6494BEM is rated for 15 V continuous operation in automotive 12 V systems with transient tolerance.

Does LMC6494BEM support true rail-to-rail input beyond the supply rails?

Yes, the LMC6494BEM supports input common-mode voltage from (V− − 0.25 V) to (V+ + 0.25 V) at room temperature, and (V− − 0.25 V) to (V+ + 0.25 V) over full temperature range for CMRR ≥50 dB. This exceeds rail capability eliminates phase inversion and enables direct interface with sensors whose output swings beyond supply limits-such as grounded thermocouples or biased piezoresistive elements. The LMC6494BEM achieves this via proprietary CMOS input topology, not clamping diodes.

What is the typical input bias current of LMC6494BEM and why does it matter?

The typical input bias current of LMC6494BEM is 150 fA, with a guaranteed maximum of 200 pA across temperature. This ultra-low value is critical when interfacing with high-impedance sources like oxygen sensors, photodiodes, or NTC thermistor dividers-where even 1 pA leakage can induce >1 mV offset error. The LMC6494BEM's 150 fA IB ensures sub-µV error contribution in 1 GΩ source impedance applications, preserving measurement fidelity in emission-critical automotive subsystems.

Can LMC6494BEM drive capacitive loads directly?

No, LMC6494BEM is not unity-gain stable with direct capacitive loads >100 pF due to output stage pole interaction. Driving cables or ADC input capacitance requires external isolation-typically a 22–100 Ω series resistor placed between LMC6494BEM output and load. For larger capacitive loads (>1 nF), a dedicated buffer stage or RC compensation network (as shown in Figure 5 of DS012049) is required. The LMC6494BEM's stability curves confirm safe operation only with resistive loads ≥600 Ω when driving >500 pF.

Is LMC6494BEM pin-compatible with LMC6494AEM?

Yes, LMC6494BEM and LMC6494AEM share identical 14-pin SOIC (M14A) packaging, pinout, and footprint. The difference lies solely in initial offset voltage specification: LMC6494AEM has max VOS of 3.0 mV, while LMC6494BEM is tighter at 6.0 mV (both tested at TJ = 25°C). Both operate identically across −40°C to +125°C and exhibit identical AC performance, making LMC6494BEM a drop-in replacement where higher initial accuracy is not required.