LTC1966 - Precision Micropower ΔΣ RMS-to-DC Converter

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 simpler 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. Differential input range is 1VPEAK, and offers unprecedented linearity. 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.

  • Simple to Use, Requires One Capacitor
  • True RMS DC Conversion Using ∆Σ 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: 2.7V to 5.5V Single Supply Up to ±5.5V Dual Supply
  • Flexible Inputs: Differential or Single-Ended Rail-to-Rail Common Mode Voltage Range Up to 1VPEAK Differential Voltage
  • Flexible Output: Rail-to-Rail Output Separate Output Reference Pin Allows Level Shifting
  • Wide Temperature Range: –55°C to 125°C
  • Small Size: Space Saving 8-Pin MSOP Package
Typical Application
LTC1966 Typical Application
LTC1966 Typical Application
  • True RMS Digital Multimeters and Panel Meters
  • True RMS AC + DC Measurements
LTC1966 Package Drawing
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
Demo Boards
Part NumberDescriptionPrice
DC427B-ALTC1966CMS8 | RMS to DC Converter$50.00
Application Note
Design Note
Reliability Data
LT Journal
CAD Symbol
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R448 Reliability Data
Mar 2002 Delta Sigma Breakthrough: LTC1966 True RMS-to-DC Converter Uses No Diodes, Heaters or Logarithms
LTC1966 Footprints and Symbols
LTC1966 Demo Circuit - AC Current Measurement