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AD549:  Ultralow Input-Bias Current Operational Amplifier

Product Details


The AD549 is a monolithic electrometer operational amplifier with very low input bias current. Input offset voltage and input offset voltage drift are laser trimmed for precision performance. The part's ultralow input current is achieved with "Topgate" JFET technology, a process development exclusive to Analog Devices, Inc. This technology allows fabrication of extremely low input current JFETs compatible with a standard junction isolated bipolar process. The 1015 Ω common-mode impedance, which results from the bootstrapped input stage, ensures that the input current is essentially independent of common-mode voltage.

The AD549 is suited for applications that require very low input current and low input offset voltage. It excels as a preamp for a wide variety of current output transducers, such as photo-diodes, photomultiplier tubes, or oxygen sensors. The AD549 can also be used as a precision integrator or low droop sample and hold. The AD549 is pin compatible with standard FET and electrometer op amps, allowing designers to upgrade the performance of present systems at little additional cost.

The AD549 is available in a TO-99 hermetic package. The case is connected to Pin 8 so that the metal case can be independently connected to a point at the same potential as the input terminals, minimizing stray leakage to the case. The AD549 is available in four performance grades. The J, K, and L versions are rated over the commercial temperature range of 0°C to +70°C. The S grade is specified over the military temperature range of −55°C to +125°C and is available processed to MIL-STD-883B, Rev. C. Extended reliability plus screening is also available. Plus screening includes 168 hour burn-in, as well as other environmental and physical tests derived from MIL-STD-883B, Rev. C.

Product Highlights

  1. The AD549 input currents are specified, 100% tested, and guaranteed after the device is warmed up. They are guaranteed over the entire common-mode input voltage range.
  2. The AD549 input offset voltage and drift are laser trim-med to 0.25 mV and 5 μV/°C (AD549K), and to 1 mV and 20 μV/°C (AD549J).
  3. A maximum quiescent supply current of 700 μA minimizes heating effects on input current and offset voltage.
  4. AC specifications include 1 MHz unity gain bandwidth and 3 V/μs slew rate. Settling time for a 10 V input step is 5 μs to 0.01%.

Applications

  • Electrometer amplifier
  • Photodiode preamp
  • pH electrode buffer
  • Vacuum ion gauge measurement

FEATURES and BENEFITS

  • Ultralow input-bias current
    60 fA maximum (AD549L)

    250 fA maximum (AD549J)
  • Input-bias current guaranteed over common-mode voltage range
  • Low offset voltage
    0.25 mV maximum (AD549K)

    1.00 mV maximum (AD549J)
  • Low offset drift
    5 μV/°C maximum (AD549K)

    20 μV/°C maximum (AD549J)
  • Low power
    700 μA maximum supply current

    Low input voltage noise
  • 4 μV p-p 0.1 Hz to 10 Hz
  • MIL-STD-883B parts available

Connection Diagram for AD549

Documentation

Title Content Type File Type
AD549: Ultralow Input-Bias Current Operational Amplifier Data Sheet (Rev H, 03/2008) (pdf, 1220 kB) Data Sheets PDF
AN-649: Using the Analog Devices Active Filter Design Tool  (pdf, 5301 kB) Application Notes PDF
AN-357: Operational Integrators  (pdf, 272 kB) Application Notes PDF
AN-356: User's Guide to Applying and Measuring Operational Amplifier Specifications  (pdf, 538 kB) Application Notes PDF
AN-253: Find Op Amp Noise with Spreadsheet  (pdf, 77 kB) Application Notes PDF
Printed Circuit Board Design (PCB) Issues  (pdf) Design Handbooks PDF
ADI Warns Against Misuse of COTS Integrated Circuits  (pdf, 13 kB)
(Revised 1/03)
Invites Customer Participation in Creative Mil/Aero System Solutions
Recommended Reading PDF
Ask The Applications Engineer-25
Op Amps Driving Capacitive Loads

(Analog Dialogue, Vol. 31, No. 2, 1997)
Analog Dialogue HTML
Low-Power, Low-Voltage IC Choices for ECG System Requirements
(Analog Dialogue, Vol. 29, No. 3, 1995)
Analog Dialogue HTML
Ask The Applications Engineer-6
Op-Amp Issues

(Analog Dialogue, 30th Anniversary Reader Bonus)
Analog Dialogue HTML
Low-Power, Low-Voltage IC Choices for ECG System Requirements
(Analog Dialogue, Vol. 29, No. 3, 1995)
Technical Articles HTML
Space Qualified Parts List  (pdf, 93 kB)
This document lists 67 (240+) space level products that are available from Analog Devices. Many of the products listed are state-of-the-art data conversion and signal processing products that were previously only available as commercial or military Class B products. Through our Space Products Group and MIL-PRF-38535 certified Level V (Class S) facility, we are pleased to offer these products to the space marketplace.
Aerospace Information PDF
What do I do with the "null pins" on the amplifier if I don't plan to use them? FAQs/RAQs HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD549 SPICE Macro Model SPICE Models HTML

Evaluation Kits & Symbols & Footprints

Symbols and Footprints— Analog Devices offers Symbols & Footprints which are compatible with a large set of today’s CAD systems for broader and easier support.

SampleSample & Buy

Price, packaging, availability

AD549 Model Options
Model Package Pins Temp.
Range
Packing,
Qty
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
Purchase/Sample
AD549JH Status: Contact ADI 8 ld Header 8 Comm. Tube, 100 - - N  Material Info PCN Contact ADI
AD549JHZ Status: Production 8 ld Header 8 Comm. Tube, 100 $16.72 $15.90 Y  Material Info PCN Purchase
AD549KH Status: Contact ADI 8 ld Header 8 Comm. Tube, 100 - - N  Material Info PCN Contact ADI
AD549KHZ Status: Production 8 ld Header 8 Comm. Tube, 100 $24.70 $23.48 Y  Material Info PCN Purchase
AD549LH Status: Contact ADI 8 ld Header 8 Comm. Tube, 100 - - N  Material Info PCN Contact ADI
AD549LHZ Status: Contact ADI 8 ld Header 8 Comm. Tube, 100 - - Y  Material Info PCN Contact ADI
AD549SH/883B Status: Production 8 ld Header 8 Mil Tube, 100 $73.84 $70.15 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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