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AD598:  LVDT Signal Conditioner

Product Details

The AD598 is a complete, monolithic Linear Variable Differential Transformer (LVDT) signal conditioning subsystem. It is used in conjunction with LVDTs to convert transducer mechanical position to a unipolar or bipolar dc voltage with a high degree of accuracy and repeatability. All circuit functions are included on the chip. With the addition of a few external passive components to set frequency and gain, the AD598 converts the raw LVDT secondary output to a scaled dc signal. The device can also be used with RVDT transducers.

The AD598 contains a low distortion sine wave oscillator to drive the LVDT primary. The LVDT secondary output consists of two sine waves that drive the AD598 directly. The AD598 operates upon the two signals, dividing their difference by their sum, producing a scaled unipolar or bipolar dc output.

The AD598 uses a unique ratiometric architecture (patent pending) to eliminate several of the disadvantages associated with traditional approaches to LVDT interfacing. The benefits of this new circuit are: no adjustments are necessary, transformer null voltage and primary to secondary phase shift does not affect system accuracy, temperature stability is improved, and transducer interchangeability is improved.


  • Single Chip Solution, Contains Internal Oscillator and Voltage Reference
  • No Adjustments Required
  • Insensitive to Transducer Null Voltage
  • Insensitive to Primary to Secondary Phase Shifts
  • DC Output Proportional to Position
  • 20 Hz to 20 kHz Frequency Range
  • Single or Dual Supply Operation
  • Unipolar or Bipolar Output
  • Will Operate a Remote LVDT at Up to
    300 Feet
  • Position Output Can Drive Up to
    1000 Feet of Cable
  • Will Also Interface to an RVDT
  • Outstanding Performance
    Linearity: 0.05% of FS max
    Output Voltage: ±11 V min
    Gain Drift: 50 ppm/°C of FS max
    Offset Drift: 50 ppm/°C of FS max

Functional Block Diagram for AD598

Of Note . . .

The AD598 is also available processed to MIL-STD-883B, for the military range of -55°C to +125°C .


Title Content Type File Type
AD598: LVDT Signal Conditioner Data Sheet  (Rev A, 10/1989) (pdf, 553 kB) Data Sheets PDF
AD598: Military Data Sheet  (Rev B, 09/1989) (pdf) Data Sheets PDF
CN0288: LVDT Signal Conditioning Circuit  (pdf, 284 kB) Circuit Note PDF
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

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Price, packaging, availability

AD598 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
5962-9067101MRA Status: Production 20 ld CerDIP 20 Mil Tube, 19 $87.41 $78.67 N  Material Info PCN Purchase
AD598AD Status: Production 20 ld Side-Brazed CerDip 20 Ind Tube, 19 $43.27 $36.05 N  Material Info PCN Purchase
AD598JR Status: Production 20 ld SOIC - Wide 20 Comm. Tube, 37 $29.25 $26.32 N  Material Info PCN Purchase
AD598JRZ Status: Production 20 ld SOIC - Wide 20 Comm. Tube, 37 $26.65 $23.97 Y  Material Info PCN Purchase
AD598SD/883B Status: Production 20 ld Side-Brazed CerDip 20 Mil Tube, 19 $90.02 $81.03 N  Material Info PCN Purchase
Price Table Help

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

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