AD546 Datasheet, PDF (1/12 Pages) Analog Devices – 1 pA Monolithic Electrometer Operational Amplifier

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FEATURES
DC PERFORMANCE
1 mV max Input Offset Voltage
Low Offset Drift: 20 ␮V/؇C
1 pA max Input Bias Current
Input Bias Current Guaranteed Over Full
Common-Mode Voltage Range
AC PERFORMANCE
3 V/␮s Slew Rate
1 MHz Unity Gain Bandwidth
Low Input Voltage Noise: 4 ␮V p-p, 0.1 Hz to 10 Hz
Available in a Low Cost, 8-Pin Plastic Mini-DIP
Standard Op Amp Pinout
APPLICATIONS
Electrometer Amplifiers
Photodiode Preamps
pH Electrode Buffers
Log Ratio Amplifiers
1 pA Monolithic Electrometer
Operational Amplifier
AD546*
CONNECTION DIAGRAM
8-Pin Plastic
Mini-DIP Package
PRODUCT DESCRIPTION
The AD546 is a monolithic electrometer combining the virtues
of low (1 pA) input bias current with the cost effectiveness of a
plastic mini-DIP package. Both input offset voltage and input
offset voltage drift are laser trimmed, providing very high perfor-
mance for such a low cost amplifier.
Input bias currents are reduced significantly by using “topgate”
JFET technology. The 10¹⁵ Ω common-mode impedance,
resulting from a bootstrapped input stage, insures that input
bias current is essentially independent of common-mode voltage
variations.
The AD546 is suitable for applications requiring both minimal
levels of input bias current and low input offset voltage. Appli-
cations for the AD546 include use as a buffer amplifier for cur-
rent output transducers such as photodiodes and pH probes. It
may also be used as a precision integrator or as a low droop rate
sample and hold amplifier. The AD546 is pin compatible with
standard op amps; its plastic mini-DIP package is ideal for use
with automatic insertion equipment.
The AD546 is available in two performance grades, all rated
over the 0°C to +70°C commercial temperature range, and
packaged in an 8-pin plastic mini-DIP.
PRODUCT HIGHLIGHTS
1. The input bias current of the AD546 is specified, 100%
tested and guaranteed with the device in the fully warmed-up
condition.
2. The input offset voltage of the AD546 is laser trimmed to
less than 1 mV (AD546K).
3. The AD546 is packaged in a standard, low cost, 8-pin
mini-DIP.
4. A low quiescent supply current of 700 µA minimizes any
thermal effects which might degrade input bias current and
input offset voltage specifications.
*Covered by Patent No. 4,639,683.
REV. A
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