LTC1968_15 Datasheet, PDF (1/28 Pages) Linear Technology – Precision Wide Bandwidth, RMS-to-DC Converter

LTC1968
Precision Wide Bandwidth,
RMS-to-DC Converter
FEATURES
■ _{High Linearity:}
0.02% Linearity Allows Simple System Calibration
■ _{Wide Input Bandwidth:}
Bandwidth to 1% Additional Gain Error: 500kHz
Bandwidth to 0.1% Additional Gain Error: 150kHz
3dB Bandwidth Independent of Input Voltage
Amplitude
■ _{No-Hassle Simplicity:}
True RMS-DC Conversion with Only One External
Capacitor
Delta Sigma Conversion Technology
■ _{Ultralow Shutdown Current:}
0.1µA
■ _{Flexible Inputs:}
Differential or Single Ended
Rail-to-Rail Common Mode Voltage Range
Up to 1V_PEAK Differential Voltage
■ _{Flexible Output:}
Rail-to-Rail Output
Separate Output Reference Pin Allows Level Shifting
■ _{Small Size:}
Space Saving 8-Pin MSOP Package
U
APPLICATIO S
■ _{True RMS Digital Multimeters and Panel Meters}
■ _{True RMS AC + DC Measurements}
DESCRIPTIO
The LTC^®1968 is a true RMS-to-DC converter that uses an
innovative delta-sigma computational technique. The ben-
efits of the LTC1968 proprietary architecture, when com-
pared to conventional log-antilog RMS-to-DC converters,
are higher linearity and accuracy, bandwidth independent
of amplitude and improved temperature behavior.
The LTC1968 operates with single-ended or differential in-
put signals and accurately supports crest factors up to 4.
Common mode input range is rail-to-rail. Differential in-
put range is 1V_PEAK, and offers unprecedented linearity. The
LTC1968 allows hassle-free system calibration at any in-
put voltage.
The LTC1968 has a rail-to-rail output with a separate out-
put reference pin providing flexible level shifting; it oper-
ates on a single power supply from 4.5V to 5.5V. A low power
shutdown mode reduces supply current to 0.1µA.
The LTC1968 is packaged in the space-saving MSOP pack-
age, which is ideal for portable applications.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Protected under U.S. Patent Numbers 6,359,576, 6,362,677 and 6,516,291
TYPICAL APPLICATIO
Single Supply RMS-to-DC Converter
4.5V TO 5.5V
DIFFERENTIAL
INPUT
0.1µF
OPT. AC
COUPLING
V⁺
IN1
OUTPUT
LTC1968
IN2 OUT RTN
EN GND
1968 TA01
C_AVE
10µF
+
–
V_OUT
Linearity Performance
0.2
LTC1968, ∆Σ
0
–0.2
–0.4
–0.6
CONVENTIONAL
LOG/ANTILOG
–0.8
60Hz SINEWAVE
–1.0
0 100 200 300
V_IN (mV AC_RMS)
400 500
1968 TA01b
1968f
1