Texas Instruments LF298M

Overview

LF298M from Texas Instruments is a monolithic BI-FET sample-and-hold IC operating as a unity-gain follower with 0.002% typical DC gain accuracy, ≤10 µs acquisition time to 0.1%, and 0.5 mV typical hold step (Ch = 0.01 µF). It functions in precision data acquisition systems where analog signal capture must maintain ultrahigh DC accuracy under ±15 V supplies.

For engineers reviewing the LF298M datasheet, LF298M pinout, LF298M application, or LF298M equivalent, key selection considerations include hold capacitor leakage (<100 pA), input impedance (10¹⁰ Ω), feedthrough attenuation (96 dB at 1 kHz), logic compatibility (TTL/PMOS/CMOS), and thermal-limited junction temperature (115°C).

Technical Context

The LF298M uses a bipolar input stage for low offset voltage and wide bandwidth, enabling stable inclusion inside the feedback loop of 1-MHz op-amps. Its P-channel JFET–bipolar output stage achieves droop rates as low as 5 mV/min with a 1-µF hold capacitor while suppressing high-temperature instability.

Logic control is fully differential with 1.4 V threshold, supporting direct TTL/PMOS/CMOS interfacing. Input offset adjustment is performed via a dedicated pin without degrading drift performance, and no feedthrough occurs from input to output in hold mode-even with input signals at supply rails.

Key Specifications

Pinout & Package

LF298M is packaged in a 14-pin SOIC (D package), 8.65 mm × 3.91 mm body size, with exposed pad not present and standard JEDEC-compliant footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar sample-and-hold applications.

Compared with LF398N and LF198N, the LF298M offers the optimal balance of SOIC packaging density, 85°C upper ambient limit, and 0.5 mV hold step - making it the default choice for modern surface-mount data acquisition modules requiring production scalability and thermal margin.

Availability

LF298M is available at Aetrix Electronics and suitable for precision data acquisition systems, automated test equipment, and industrial process monitoring requiring stable component supply across multi-year production cycles.

Supply support for LF298M 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 is a global semiconductor leader specializing in analog and embedded processing technologies, with over 90 years of innovation in precision signal chain components.

The LFx98x product line was designed specifically for high-fidelity sample-and-hold applications in test & measurement, medical instrumentation, and radar signal conditioning - prioritizing DC accuracy, low droop, and logic interoperability over cost or integration density.

FAQ

What is the maximum recommended hold capacitor value for LF298M to maintain ≤10 µs acquisition time?

The LF298M achieves ≤10 µs acquisition time to 0.1% with a 0.01 µF hold capacitor. Increasing capacitance slows acquisition: at 0.1 µF, acquisition extends to ~20 µs per datasheet Section 6.4. For fastest settling, use 1000 pF–0.01 µF film capacitors (polypropylene preferred). Larger values improve droop but degrade speed - always verify against actual signal slew rate.

Can LF298M operate with single-supply configurations?

No, LF298M requires dual symmetric supplies (±5 V to ±18 V) as specified in Absolute Maximum Ratings and Recommended Operating Conditions. Its bipolar input stage and internal biasing depend on balanced rails. Attempting single-supply operation violates the −VS + 3.5 V ≤ V_IN ≤ +VS − 3.5 V input range and risks latch-up or undefined behavior.

How does LF298M handle logic signals from 3.3-V CMOS microcontrollers?

LF298M accepts 3.3-V CMOS logic directly: its differential logic threshold is 1.4 V, and the LOGIC pin tolerates input voltages up to ±30 V relative to LOGIC REFERENCE. Tie LOGIC REFERENCE to ground, and drive LOGIC with 0 V / 3.3 V - the 1.4 V threshold ensures clean transition without external resistors or level shifters.

What is the purpose of the OFFSET ADJUST pin on LF298M, and how is it configured?

The OFFSET ADJUST pin on LF298M trims input offset voltage to <3 mV using a 1-kΩ potentiometer: connect one end to V+, the other to ground via a resistor (set for ~0.6 mA total current), and the wiper to OFFSET ADJUST. This adjustment does not degrade temperature drift - a key advantage over amplifier-based nulling circuits. Full procedure is in Section 9.1.2 of the datasheet.

Why does LF298M specify different junction temperature limits than LF198N or LF398N?

LF298M has a maximum junction temperature (T_JMAX) of 115°C, lower than LF198N (150°C) and higher than LF398N (100°C), reflecting its SOIC package's thermal resistance (R_θJA = 80.6°C/W). This rating ensures reliable operation at 85°C ambient with proper PCB copper area - exceeding commercial-grade requirements while avoiding military-cost packaging.