描述 Description

The AD7769 is a complete, two-channel, 8-bit, analog I/O port.It has versatile input and output signal conditioning featuresthat make it ideal for use in head-positioning servos in Winchesterdisk systems. It is equally suitable for floppy disk microsteppinghead positioning, other closed loop digital servo systemsand general purpose 8-bit data acquisition.The AD7769 contains a high speed successive approximationADC, preceded by a two-channel multiplexer and signal conditioningcircuits. The input span of the ADC and the offset ofthe zero point from ground can be independently set by applyingground referenced voltages. The AD7769 also contains twoindependent, fast settling, 8-bit DACs with output amplifiers.The output span and offset voltage of the DACs can be set independentlyof those of the ADC. This makes the AD7769 especiallyuseful in disk drives, where only a positive supply rail isavailable and the ranges of the ADC and DACs must be referencedto some positive voltage less than the supply.The AD7769 is easily interfaced to a standard 8-bit mpu bus viaan 8-bit data port and standard microprocessor control lines.The AD7769 is fabricated in Linear Compatible CMOS(LC2MOS), an advanced, mixed technology process that combinesprecision bipolar circuits with low power CMOS logic.The part is available in a 28-lead plastic DIP and 28-terminalPLCC package.