CMOS 12-Bit Successive Approximation ADC

The AD7578 is a medium speed, monolithic 12-bit CMOS A/D converter which uses the successive approximation technique to provide a conversion time of 100µs. An auto-zero cycle occurs at the start of each conversion resulting in very low system offset voltages, typically less than 100µV. The device is designed for easy microprocessor interfacing using standard control signals; CS (decoded device address), RD (READ) and WR (WRITE).

Conversion results are available in two bytes, 8LSBs and 4MSBs, over an 8-bit three state output bus. Either byte can be read first. Two converter busy flags are available to facilitate polling of the converter's status.

The analog input voltage range is 0V to +5V when using a reference voltage of +5V.

PRODUCT HIGHLIGHTS

* The AD7578 is a complete 12-bit A/D converter in a 24-pin

package requiring only a few passive components and a voltge reference

* Autozero cycle realizes very low offset voltages, typically 100µV

* Standard microprocessor control signals to allow easy interfacing

to most popular 8- and 16-bit processors.

* Monolithic construction for increased reliability and small 0.3", 24-pin package.

* 12-Bit Successive Approximation ADC

* No Missed Codes Over Full Temperature Range

* Low Total Unadjusted Error ±1LSB max

* High Impedance Analog Input