AD694AQ (ANALOG DEVICES)

The AD694AQ is a monolithic Current Transmitter accepts high level signal inputs to drive a standard 4 to 20mA current loop for the control of valves, actuators and other devices commonly used in process control. The input signal is buffered by an input amplifier that can be used to scale the input signal or buffer the output from a current mode DAC. Pre-calibrated input spans of 0 to 2V and 0 to 10V are selected by simple pin strapping, other spans may be programmed with external resistors. The output stage compliance extends to within 2V of VS and its special design allows the output voltage to extend below common in dual supply operation. An alarm warns of an open 4 to 20mA loop or noncompliance of the output stage. Active laser trimming of the AD694's thin film resistors results in high levels of accuracy without the need for additional adjustments and calibration.