National Semiconductor has introduced a 16bit DAC featuring a single-wire interface and 4 to 20mA current loop drive that is claimed to simplify the design of smart transmitters used in industrial two-wire sensor systems. The DAC161P997 reduces component count in factory and building automation control systems by enabling the use of a single isolation component to cross the isolation boundary, says the company. For sensing and detecting applications where galvanic isolation is not required, the DAC is claimed to directly interface to a microcontroller. The delta-sigma DAC has a temperature coefficient of 29ppm and output current drift of 90ppm, while consuming less than 190µA of supply current. The DAC's loop drive interfaces to a HART (highway addressable remote transducer) modulator, allowing injection of FSK-modulated digital data into the current loop. The DAC operates between -40 and 125°C. According to the company, the low power operation enables total system power consumption below 30mW or 3.5mA. It has user-programmable start up conditions, data rate auto detect which allows system configuration for trade-off between update-rate versus power consumption, and automatic error detection and reporting features. The DAC is suitable for gas, temperature and pressure sensor applications and is offered in a 4x4mm LLP package.
