An eight-channel 8 bit microprocessor compatible NMOS D/A converter with programmable scaling

Abstract

A single-chip multiple-channel D/A converter is described. The NMOS chip contains a combination of digital and analog functions. Eight output channels with 8 bit accuracy are provided and each channel has programmable end points. The values for the data and the end points are stored in an internal RAM. Sample and-hold functions are completely on-chip. Only one multiplexed opamp is required for the analog functions. The entire control logic is incorporated in an easily testable PLA. The active chip area is 8 mm/SUP 2/. There are three power supplies (15,5,-5) with a total power dissipation of 120 mW. Updating of the eight channels occurs at a 16 kHz rate (5 MHz clock). The circuit aims at applications in microprocessor driven control systems in the industrial and consumer products field.