LF198QML_14 Datasheet, PDF (1/22 Pages) Texas Instruments – Monolithic Sample-and-Hold Circuits

LF198QML
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SNOSAH9A – FEBRUARY 2005 – REVISED MARCH 2013
LF198QML Monolithic Sample-and-Hold Circuits
Check for Samples: LF198QML
FEATURES
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•2 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
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
bandwidth allows the LF198 to be included inside the
feedback loop of 1 MHz op amps without having
stability problems. Input impedance of 10¹⁰Ω 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 with a 1 μF 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 specifies
no feed-through from input to output in the hold
mode, even for input signals equal to the supply
voltages.
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.
Connection Diagrams
Figure 1. Small-Outline Package (CGLA)
See Package Number NAC0014A
Figure 2. Metal Can Package (TO-99)
See Package Number LMC0008C
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2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
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