AD694JN

Product Details

The AD693 is a single-chip signal conditioning circuit that accepts low-level inputs from various sensors to control a standard 4-20 mA two-wire current loop. It provides an on-chip voltage reference and auxiliary amplifier for sensor excitation; excitation current can be up to 3.5 mA when the device operates in loop-powered mode. Alternatively, when a 0-20 mA supply is required, the device can be locally powered for 3-wire applications.

Pre-calibrated 30 mV and 60 mV input ranges can be programmed with simple pin binding. External resistors can also be added for additional ranges from 1 mV to 100 mV. Auxiliary amplifiers can be combined with on-chip voltages to provide six pre-calibrated ranges for 100Ω RTDs. Output ranges and zero outputs are also pin-strapped for standard ranges: 4-20mA, 12 ± 8 mA, and 0-20 mA.

After active laser trimming of the AD693's thin-film resistors, high accuracy is achieved without additional trimming and calibration. All devices are tested and the total unregulated error is less than 0.5% of full scale at +25°C and less than 0.75% over the industrial temperature range. The residual nonlinearity is less than 0.05%. The AD693 can also use an external pass tube to further reduce self-heating errors.

The AD693 provides a cost-effective signal conditioning solution for low-level signaling of RTDs, bridges, and pressure sensors. It is recommended to replace discrete circuit designs in various applications such as process control, factory automation, and system monitoring.

The AD693 is available in 20-lead ceramic side-soldered DIP, 20-lead Cerdip, and 20-lead LCCC packages, and is specified over the industrial temperature range of ?40°C to +85°C.

Features and Benefits

Instrumentation Amplifier Front End

loop power supply

Independently adjustable output span and zero output

Pre-calibrated output ranges: 4-12 mA unipolar 0-20 mA unipolar 12 ± 8mA bipolar

Pre-calibrated 20 mV or 60mV input range

Pre-calibrated 100 O RTD interface

6.2 V reference that can source up to 3.5 mA

Non-dedicated auxiliary amplifier for greater flexibility

Optional external pass tube to reduce self-heating errors