AD7769

The AD7769 is a complete, two-channel, 8-bit, analog I/O port. It has versatile input and output signal conditioning features that make it ideal for use in head-positioning servos in Winches- ter disk systems. It is equally suitable for floppy disk microstep-ping head positioning, other closed loop digital servo systems and general purpose 8-bit data acquisition.

The AD7769 contains a high speed successive approximation ADC, preceded by a two-channel multiplexer and signal condi-tioning circuits. The input span of the ADC and the offset of the zero point from ground can be independently set by apply- ing ground referenced voltages. The AD7769 also contains two independent, fast settling, 8-bit DACs with output amplifiers.The output span and offset voltage of the DACs can be set inde-pendently of those of the ADC. This makes the AD7769 espe-cially useful in disk drives, where only a positive supply rail is available and the ranges of the ADC and DACs must be refer- enced to some positive voltage less than the supply.

The AD7769 is easily interfaced to a standard 8-bit mpu bus via an 8-bit data port and standard microprocessor control lines.The AD7769 is fabricated in Linear Compatible CMOS (LC² MOS), an advanced, mixed technology process that com-bines precision bipolar circuits with low power CMOS logic. The part is available in a 28-lead plastic DIP and 28-terminal
PLCC package.