Texas Instruments LF398N Sample and Hold Amplifier IC, DIP-8, 1MHz

Texas Instruments LF398N Sample and Hold Amplifier IC is a monolithic sample-and-hold integrated circuit in an 8-pin DIP package, built with BI-FET technology for precision analogue signal processing. It operates as a unity-gain follower with a typical DC gain accuracy of 0.002%.

Overview

The LF398N/NOPB can acquire a signal to within 0.01% in as little as 6 µs. Its bipolar input stage provides a low input offset voltage and a wide bandwidth, which allows the circuit to be used within the feedback loop of 1MHz operational amplifiers without introducing stability issues.

Key Features

• Ultra-high input impedance of 10¹⁰Ω, allowing the circuit to interface with high-source impedances without any loss of accuracy
• P-channel JFETs in the output amplifier give very low droop rates, typically 5 mV per minute with a 1 µF hold capacitor
• These JFETs offer lower noise and greater temperature stability than the MOS devices used in earlier designs
• Control logic input is fully compatible with TTL, PMOS, and CMOS logic levels for straightforward integration into digital control systems
• Input characteristics remain consistent when switching between sample and hold modes, and the device maintains a high supply rejection ratio in both states

Specifications

• Package: Standard 8-pin DIP (Dual In-line Package)
• Supply voltage: ±15 V, with an operating range from ±5 V to ±18 V
• Power dissipation: 500 mW
• Typical hold step: 0.5 mV with a 0.01 µF capacitor
• Dimensions: Width 3.3, Depth 1.5, Height 4.3
• Weight: 2.117 g

Handling

This device has limited built-in ESD protection, so care should be taken during storage and handling. Its specifications make it suited to precision analogue designs where accurate sampling and holding of a signal is required.