Single-Supply, Rail-to-Rail, Low Power FET-Input Op Amp

The AD820 is a precision, low power FET input op amp that can operate from a single supply of 5 V to 36 V, or dual supplies of ±2.5 V to ±18 V. It has true single-supply capability, with an input voltage range extending below the negative rail, allowing the AD820 to accommodate input signals below ground in the single-supply mode. Output voltage swing extends to within 10 mV of each rail, providing the maximum output dynamic range.

Offset voltage of 800 μV maximum, offset voltage drift of 2 μV/°C, typical input bias currents below 25 pA, and low input voltage noise provide dc precision with source impedances up to 1 GΩ. 1.8 MHz unity gain bandwidth, −93 dB THD at 10 kHz, and 3 V/μs slew rate are provided for a low supply current of 800 μA. The AD820 drives up to 350 pF of direct capacitive load and provides a minimum output current of 15 mA. This allows the amplifier to handle a wide range of load conditions. This combination of ac and dc performance, plus the outstanding load drive capability, results in an exceptionally versatile amplifier for the single-supply user.

The AD820 is available in two performance grades. The A and B grades are rated over the industrial temperature range of −40°C to +85°C. The AD820 is offered in three 8-lead package options: plastic DIP (PDIP), surface mount (SOIC) and (MSOP).

Applications

* Battery-powered precision instrumentation

* Photodiode preamps

* Active filters

* 12-bit to 14-bit data acquisition systems

* Medical instrumentation

* Low power references and regulators

Data Sheet, Rev. F, 11/08

* True single-supply operation

Output swings rail-to-rail

Input voltage range extends below ground

Single-supply capability from 5 V to 36 V

Dual-supply capability from ±2.5 V to ±18 V

* Excellent load drive

Capacitive load drive up to 350 pF

Minimum output current of 15 mA

* Excellent ac performance for low power

800 μA maximum quiescent current

Unity-gain bandwidth: 1.8 MHz

Slew rate of 3 V/μs

* Excellent dc performance

800 μV maximum input offset voltage

2 μV/°C typical offset voltage drift

25 pA maximum input bias current

* Low noise: 13 nV/√Hz @ 10 kHz