Texas Instruments LF298MX

Overview

LF298MX 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 signal capture stability, low droop, and high input impedance (10¹⁰ Ω) are critical - such as in high-resolution ADC front-ends and analog computing circuits.

For engineers reviewing the LF298MX datasheet, LF298MX pinout, LF298MX application, or LF298MX equivalent, key selection considerations include its ±5-V to ±18-V dual-supply operation, differential TTL/CMOS-compatible logic interface (1.4 V threshold), SOIC-14 package thermal profile (R_θJA = 80.6°C/W), and guaranteed performance over –25°C to +85°C ambient.

Technical Context

The LF298MX uses a bipolar input stage combined with P-channel JFET output devices to achieve low offset voltage (≤3 mV typ), wide bandwidth (enabling stable inclusion inside 1-MHz op-amp feedback loops), and low hold-mode droop (5 mV/min with 1 µF capacitor). Its BI-FET architecture ensures input characteristics remain unchanged during hold mode and eliminates feedthrough even at rail-to-rail input signals.

Logic control is fully differential: LOGIC and LOGIC REFERENCE pins define sample/hold state via a 1.4 V threshold; acquisition is triggered when LOGIC exceeds LOGIC REFERENCE by ≥1.4 V. Input offset is trimmed externally via a single OFFSET ADJUST pin without degrading drift performance.

Key Specifications

Pinout & Package

LF298MX is housed in a 14-pin SOIC (D package), 8.65 mm × 3.91 mm body size, with exposed pad not specified. Thermal resistance is R_θJA = 80.6°C/W under standard board-mount conditions (400 LF/min airflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LF398N and LF198AN, the LF298MX offers the optimal balance of industrial temperature range, SOIC-14 surface-mount compatibility, and production-ready DC performance - making it the preferred choice for volume-manufactured test equipment and embedded DAQ modules.

Availability

LF298MX is available at Aetrix Electronics and suitable for high-resolution data acquisition, programmable integrators, synchronous correlators, and ramp generator systems requiring stable component supply across multi-year production cycles.

Supply support for LF298MX 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, embedded processing, and connectivity technologies, with decades of heritage in precision analog IC design.

The LF298MX belongs to TI's LFx98x monolithic sample-and-hold product line, engineered specifically for high-fidelity signal capture in instrumentation, automated test equipment, and real-time control systems demanding ultrahigh DC accuracy and fast acquisition.

FAQ

What is the maximum recommended hold capacitor value for LF298MX?

The LF298MX supports hold capacitors from 0.001 µF up to 1 µF. Larger values reduce droop rate (e.g., 5 mV/min with 1 µF) but increase acquisition time - 0.01 µF is typical for balancing speed and hold stability. Capacitor dielectric matters: polypropylene or C0G ceramic is preferred to minimize dielectric absorption error; avoid high-hysteresis types like standard ceramics or mylar.

Does LF298MX require external passive components for basic operation?

Yes - LF298MX requires an external hold capacitor (Ch) connected directly to Pin 8, plus a dual ±5 V to ±18 V supply. For DC offset correction, a 1-kΩ potentiometer between V+ and ground (wiper to OFFSET ADJUST) is recommended. No external op-amps or resistors are needed for unity-gain follower operation, but decoupling capacitors (e.g., 0.1 µF ceramic per supply pin) are essential for noise suppression.

Can LF298MX operate with single-supply configurations?

No - LF298MX is designed exclusively for dual ±5 V to ±18 V supplies. Its internal BI-FET architecture and rail-to-rail input capability depend on symmetric positive and negative rails. Single-supply operation is not supported, and attempting it risks damage or undefined behavior. For single-supply sample-and-hold needs, consider purpose-built alternatives like the MAX196 or LTC1098.

What logic families are compatible with LF298MX's LOGIC input?

LF298MX's differential LOGIC input is compatible with TTL, PMOS, and CMOS families. It requires a minimum 1.4 V differential between LOGIC and LOGIC REFERENCE pins for reliable mode switching. For TTL/CMOS (3–7 V logic high), tie LOGIC REFERENCE to ground and drive LOGIC with 0 V / 5 V. For higher-voltage CMOS (7–15 V), use the biasing scheme in Figure 20 of the datasheet to maintain correct threshold referencing.

How does temperature affect LF298MX's hold step and leakage performance?

Hold step remains stable over temperature, but leakage current into the hold capacitor doubles every 11°C rise above 25°C - e.g., 100 pA at 25°C becomes ~200 pA at 36°C. This directly impacts hold-time accuracy: at 85°C ambient, leakage may exceed 500 pA, limiting usable hold duration with small capacitors. Derating curves in Figure 7 of the datasheet should guide thermal design and capacitor selection.