LF198QML datasheet(2/20 Pages) TI1

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LF198QML

Monolithic Sample-and-Hold Circuits

General Description

The LF198 is a monolithic sample-and-hold circuit which

utilizes BI-FET technology to obtain ultra-high dc accuracy

with fast acquisition of signal and low droop rate. Operating

as a unity gain follower, dc gain accuracy is 0.002% typical

and acquisition time is as low as 6 µs to 0.01%. A bipolar

input stage is used to achieve low offset voltage and wide

bandwidth. Input offset adjust is accomplished with a single

pin, and does not degrade input offset drift. The wide band-

width allows the LF198 to be included inside the feedback

loop of 1 MHz op amps without having stability problems.

Input impedance of 10

Ω allows high source impedances to

be used without degrading accuracy.

P-channel junction FET’s are combined with bipolar devices

in the output amplifier to give droop rates as low as 5 mV/min

witha1µF hold capacitor. The JFET’s have much lower

noise than MOS devices used in previous designs and do

not exhibit high temperature instabilities. The overall design

guarantees no feed-through from input to output in the hold

mode, even for input signals equal to the supply voltages.

Features

Operates from ±5V to ±18V supplies

Less than 10 µs acquisition time

TTL, PMOS, CMOS compatible logic input

0.5 mV typical hold step at C

h = 0.01 µF

Low input offset

0.002% gain accuracy

Low output noise in hold mode

Input characteristics do not change during hold mode

High supply rejection ratio in sample or hold

Wide bandwidth

Logic inputs on the LF198 are fully differential with low input

current, allowing direct connection to TTL, PMOS, and

CMOS. Differential threshold is 1.4V. The LF198 will operate

from ±5V to ±18V supplies.

Ordering Information

NSC Part Number

JAN Part Number

NSC Package Number

Package Description

LF198H/883

5962–8760801GA

H08C

8LD Metal Can

LF198WG-QMLV

5962–8760801VZA

WG14A

14LD Ceramic SOIC

LF198WG/883

5962–8760801QZA

WG14A

14LD Ceramic SOIC

Connection Diagrams

Small-Outline Package

Metal Can Package

20122215

See NS Package Number WG14A

20122214

See NS Package Number H08C

February 2005

DS201222

LF198QML Datasheet(PDF) 2 Page - Texas Instruments

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