CONNECTION DIAGRAM

8-Pin Plastic

Mini-DIP Package

REV. A

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reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

a

1 pA Monolithic Electrometer

Operational Amplifier

AD546*

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

Fax: 617/326-8703

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

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 10

15

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.

*Covered by Patent No. 4,639,683.

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.