LTC1966 internal delta-sigma circuitry of the LTC1966 makes it sim- Application Circuit

Linear Technology Corporation

find LTC1966 datasheet
LTC1966 circuit
FEATURES
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LTC1966
Precision Micropower,
∆Σ
RMS-to-DC Converter
DESCRIPTIO
The LTC
®
1966 is a true RMS-to-DC converter that utilizes
an innovative patented
∆Σ
computational technique. The
internal delta-sigma circuitry of the LTC1966 makes it sim-
pler to use, more accurate, lower power and dramatically
more flexible than conventional log-antilog RMS-to-DC
converters.
The LTC1966 accepts single ended or differential input
signals (for EMI RFI rejection) and supports crest factors
up to 4. Common mode input range is rail-to-rail. Differ-
ential input range is 1V
PEAK
, and offers unprecedented lin-
earity. Unlike previously available RMS-to-DC converters,
the superior linearity of the LTC1966 allows hassle-free
system calibration at any input voltage.
The LTC1966 also has a rail-to-rail output with a separate
output reference pin providing flexible level shifting. The
LTC1966 operates on a single power supply from 2.7V to
5.5V or dual supplies up to
±5.5V.
A low power shutdown
mode reduces supply current to 0.5µA.
The LTC1966 is insensitive to PC board soldering and
stresses, as well as operating temperature. The LTC1966
is packaged in the space-saving MSOP package which is
ideal for portable applications.
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APPLICATIO S
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True RMS Digital Multimeters and Panel Meters
True RMS AC + DC Measurements
, LTC and LT are registered trademarks of Linear Technology Corporation.
Protected under U.S. Patent Numbers 6,359,576 and 6,362,677
TYPICAL APPLICATIO
Quantum Leap in Linearity Performance
LINEARITY ERROR (V
OUT
mV DC – V
IN
mV AC
RMS
)
0.2
0
LTC1966
∆Σ
Single Supply RMS-to-DC Converter
2.7V TO 5.5V
V
DD
IN1
DIFFERENTIAL
INPUT
0.1µF
OPT. AC
COUPLING
IN2
EN
OUTPUT
LTC1966
OUT RTN
V
SS
GND
C
AVE
1µF
1966 TA01
–0.2
–0.4
–0.6
–0.8
–1.0
0
60Hz SINEWAVES
50 100 150 200 250 300 350 400 450 500
V
IN
(mV AC
RMS
)
1966 TA01b
CONVENTIONAL
LOG/ANTILOG
+
V
OUT
U
No-Hassle Simplicity:
True RMS-DC Conversion with Only One External
Delta Sigma Conversion Technology
High Accuracy:
0.1% Gain Accuracy from 50Hz to 1kHz
0.25% Total Error from 50Hz to 1kHz
High Linearity:
0.02% Linearity Allows Simple System Calibration
Low Supply Current:
155µA Typ, 170µA Max
Ultralow Shutdown Current:
0.1µA
Constant Bandwidth:
Independent of Input Voltage
800kHz –3dB, 6kHz
±1%
Flexible Supplies:
Up to
±5.5V
Dual Supply
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
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sn1966 1966fas
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