Datasheet AD549 (Analog Devices)

Ultralow Input Bias Current Operational Amplifier Data Sheet AD549 FEATURES CONNECTION DIAGRAM GUARD PIN, Ultralow input bias current CONNECTED TO CASE 60 fA maximum (AD549L) OFFSET NULL 100 fA maximum (AD549K) 8 V+ 1 AD549 7 250 fA maximum (AD549J) Input bias current guaranteed over the common-mode INVERTING 2 6 OUTPUT INPUT voltage range Low offset voltage 3 5 NONINVERTING OFFSET 0.50 mV maximum (AD549K) INPUT 4 NULL V– 1.00 mV maximum (AD549J) Low offset drift 10kΩ 1 5 15 μV/°C maximum (AD549K) 4 –15V 20 μV/°C maximum (AD549J) VOS TRIM
01 0
Low power
1- 051 0
700 μA maximum supply current
Figure 1.
Low input voltage noise 4 μV (typ) p-p over 0.1 Hz to 10 Hz MIL-STD-883B parts available APPLICATIONS Electrometer amplifier Photodiode preamp pH electrode buffer GENERAL DESCRIPTION
connected to a point at the same potential as the input terminals, The AD549 is a monolithic electrometer operational amplifier minimizing stray leakage to the case. The AD549 is available in with very low input bias current. Input offset voltage and input four performance grades. The J, K, and L versions are rated over offset voltage drift are laser trimmed for precision performance. the commercial temperature range of 0°C to +70°C. The S grade The ultralow input current of the part is achieved with Topgate™ is specified over the military temperature range of −55°C to +125°C JFET technology, a process development exclusive to Analog and is available processed to MIL-STD-883B, Rev. C. Extended Devices, Inc. This technology allows fabrication of extremely reliability plus screening is also available. Plus screening includes low input current JFETs compatible with a standard junction 168 hour burn-in, as well as other environmental and physical isolated bipolar process. The 1015 Ω common-mode impedance, tests derived from MIL-STD-883B, Rev. C. which results from the bootstrapped input stage, ensures that
PRODUCT HIGHLIGHTS
the input current is essentially independent of the common- 1. The AD549 input currents are specified, 100% tested, and mode voltage. guaranteed after the device is warmed up. They are guaran- The AD549 is suited for applications requiring very low input teed over the entire common-mode input voltage range. current and low input offset voltage. It excels as a preamp for a 2. The AD549 input offset voltage and drift are laser trimmed wide variety of current output transducers, such as photodiodes, to 0.50 mV and 15 μV/°C (AD549K), and to 1 mV and photomultiplier tubes, or oxygen sensors. The AD549 can also 20 μV/°C (AD549J). be used as a precision integrator or low droop sample-and-hold. The AD549 is pin compatible with standard FET and electrometer 3. A maximum quiescent supply current of 700 μA minimizes op amps, allowing designers to upgrade the performance of heating effects on input current and offset voltage. present systems at little additional cost. 4. AC specifications include 1 MHz unity-gain bandwidth The AD549 is available in a TO-99 hermetic package. The case and 3 V/μs slew rate. Settling time for a 10 V input step is is connected to Pin 8, thus, the metal case can be independently 5 μs to 0.01%.
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Document Outline FEATURES APPLICATIONS CONNECTION DIAGRAM GENERAL DESCRIPTION PRODUCT HIGHLIGHTS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS FUNCTIONAL DESCRIPTION MINIMIZING INPUT CURRENT CIRCUIT BOARD NOTES OFFSET NULLING AC RESPONSE WITH HIGH VALUE SOURCE AND FEEDBACK RESISTANCE COMMON-MODE INPUT VOLTAGE OVERLOAD DIFFERENTIAL INPUT VOLTAGE OVERLOAD INPUT PROTECTION SAMPLE-AND-DIFFERENCE CIRCUIT TO MEASURE ELECTROMETER LEAKAGE CURRENTS PHOTODIODE INTERFACE Photodiode Preamp Noise LOG RATIO AMPLIFIER TEMPERATURE COMPENSATED pH PROBE AMPLIFIER OUTLINE DIMENSIONS ORDERING GUIDE