National Semiconductor Launches Single-Wire 16-Bit DAC for 4-20mA Loops
Supports single-isolation data transfer with a low-power 16-bit delta-sigma DAC

August 16, 2011 – National Semiconductor Korea (CEO: Choi Choong-won) today announced the introduction of a 16-bit digital-to-analog converter (DAC) featuring a single-wire interface and 4 to 20 mA current loop drive that simplifies the design of smart transmitters used in industrial two-wire sensor systems.

The highly integrated DAC161P997 reduces the number of components and costs required during manufacturing, enabling the use of a single isolation component across the isolation boundary, enabling the construction of automated control systems. National's DAC161P997 also exchanges information directly with microcontrollers, enabling detection and monitoring in applications that do not require galvanic isolation.

The low-power DAC161P997 allows system designers to optimize accuracy, ease of use, performance, and system cost. This delta-sigma DAC delivers 16-bit accuracy while maintaining a minimum temperature coefficient of 29 ppm and long-term output current drift of 90 ppm, consuming less than 190 uA of supply current.

The DAC161P997's loop drive supports FSK modular digital data transfer to a 4 to 20 mA current loop via an interface with a Highway Addressable Remote Transducer (HART) modulator. The DAC operates over the industrial temperature range of −40 °C to 85 °C.

Key Features and Benefits of the DAC161P997
• Single-wire interface: Improves system accuracy compared to discrete PWM implementations and reduces system cost compared to 4-wire SPI solutions.
• Low-power operation: Reduces system power consumption to less than 30 mW or 3.5 mA via 190 uA.
• User-programmable startup conditions and automatic data rate detection: System configuration allows balancing the trade-off between update rate and power consumption
• Error detection and reporting: Various error conditions can be automatically detected to improve system stability.

The DAC161P997 is applicable to smart transmitter designs, including a variety of gas, temperature, and pressure sensor applications, and complements National's innovative sensor AFE family.

Pricing and Availability
The DAC161P997 is available in a 16-pin, 4 mm x 4 mm LLP® package and is priced at $4 each in 1,000-unit quantities. Additional information and to order samples and evaluation boards can be found at the link below.
http://www.national.com/pf/DA/DAC161P997.html