Analog And Digital ICs Mate To Deliver High-Resolution ADC

An 18-bit dual-slope integrating A/D converter that is said to minimize mixed-signal crosstalk and noise has been formed by combining separate analog and digital chips. The ALD500R analog IC with on-chip precision voltage reference functions as the dual-slope integrator, while the ALD521D pre-programmed (digital) microprocessor provides the necessary control and handshake functions for outputting a 24-bit serial binary data word. The ALD521D also features separate control inputs for power-down, chip select and integration time select operations.
In power-down mode, the two-chip set consumes less than 28 µA. Applications for the ADC include PC-based digital panel meters, process monitors, dataloggers, and more. The set costs $6.91 each/1,000. A circuit board containing the ADC chips plus a 25-pin connector for interfacing the module to a PC is also available for $99.