AD549JHZ

AD549JHZ FEATURES

Ultralow input bias current60 fA maximum (AD549L)100 fA maximum (AD549K)250 fA maximum (AD549J)Input bias current guaranteed over the common-modevoltage rangeLow offset voltage0.50 mV maximum (AD549K)1.00 mV maximum (AD549J)Low offset drift15 μV/°C maximum (AD549K)20 μV/°C maximum (AD549J)Low power700 μA maximum supply currentLow input voltage noise4 μV (typ) p-p over 0.1 Hz to 10 HzMIL-STD-883B parts available

AD549JHZ GENERAL DESCRIPTION

The AD549 is a monolithic electrometer operational amplifierwith very low input bias current. Input offset voltage and inputoffset voltage drift are laser trimmed for precision performance.The ultralow input current of the part is achieved with Topgate™JFET technology, a process development exclusive to AnalogDevices, Inc. This technology allows fabrication of extremelylow input current JFETs compatible with a standard junctionisolated bipolar process. The 1015 Ω common-mode impedance,which results from the bootstrapped input stage, ensures thatthe input current is essentially independent of the common-mode voltage.The AD549 is suited for applications requiring very low inputcurrent and low input offset voltage. It excels as a preamp for awide variety of current output transducers, such as photodiodes,photomultiplier tubes, or oxygen sensors. The AD549 can alsobe used as a precision integrator or low droop sample-and-hold.The AD549 is pin compatible with standard FET and electrometerop amps, allowing designers to upgrade the performance ofpresent systems at little additional cost.The AD549 is available in a TO-99 hermetic package. The caseis connected to Pin 8, thus, the metal case can be independentlyconnected to a point at the same potential as the input terminals,minimizing stray leakage to the case. The AD549 is available infour performance grades. The J, K, and L versions are rated overthe commercial temperature range of 0°C to +70°C. The S gradeis specified over the military temperature range of −55°C to +125°Cand is available processed to MIL-STD-883B, Rev. C. Extendedreliability plus screening is also available. Plus screening includes168 hour burn-in, as well as other environmental and physicaltests derived from MIL-STD-883B, Rev. C.

AD549JHZ APPLICATIONS

Electrometer amplifierPhotodiode preamppH electrode buffer