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 AD549's ultralow input current is achieved with "Topgate" JFET technology, a process development exclusive to Analog Devices. This technology allows the fabrication of extremely low input current JFETs compatible with a standard junctionisolated bipolar process. The 1015W common-mode impedance, a result of the bootstrapped input stage, insures that the input current is essentially independent of common-mode voltage.
The AD549 is suited for applications requiring very low input current and low input offset voltage. It excels as a preamp for a wide variety of current output transducers such as photodiodes, 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 0 to +70. The S grade is specified over the military temperature range of 55 to +125 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.
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·Electrometer Amplifiers·Photodiode Preamp·pH Electrode Buffer·Vacuum lon Gage Measurement
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Ultralow Bias Current: 60 fA max (AD549L) 250 fA max (AD549J)Input Bias Current Guaranteed Over Common-Mode Voltage RangeLow Offset Voltage: 0.25 V max (AD549K) 1.00 V max (AD549J)Low Offset Drift: 5 mV/8C max (AD549K)20 mV/8C max (AD549J)Low Power: 700 A max Supply CurrentLow Input Voltage Noise: 4 mV p-p 0.1 Hz to 10 HzMIL-STD-883B Parts Available
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Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V
Internal Power Dissipation . . . . . . . . . . . . . . . . . . . . . . 500 mW
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V2
Output Short Circuit Duration . . . . . . . . . . . . . . . . . Indefinite
Differential Input Voltage . . . . . . . . . . . . . . . . . . +VS and VS
Storage Temperature Range (H) . . . . . . . . . .65 to +125
Operating Temperature Range
AD549J (K, L) . . . . . . . . . . . . . . . . . . . . . . . . 0 to +70
AD549S . . . . . . . . . . . . . . . . . . . . . . . . . . 55 to +125
Lead Temperature Range (Soldering 60 sec) . . . . . . . . +300
Post a Buying Lead
Required Field 
