AD7578: CMOS 12-Bit Siccessive Approximation ADC0 pages

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ANALOG

DEVICES

CMOS

12-Bit Successive Approximation ADC

AD7578

FEATURES

12-Bit Successive Approximation ADC

No Missed Codes Over Full Temperature Range

Low Total Unadjusted Error ± 1LSB max

High Impedance Analog Input

Autozero Cycle for Low Offset Voltage

Low Power, 75mW typ

Small Size: 0.3", 24-Pin Package

Conversion Time of 100(xs

GENERAL DESCRIPTION

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 lOOjxs. An auto-zero cycle occurs

at the start of each conversion resulting in very low system

offset voltages, typically less than lOOp-V. 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 OV to + 5V when using a

reference voltage of +5V.

FUNCTIONAL BLOCK DIAGRAM

12-BIT DAC —I

CLK

OSC

M \ DATA

<20) BUSY

PRODUCT HIGHLIGHTS

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

package requiring only a few passive components and a voltage

reference.

2. Autozero cycle realizes very low offset voltages, typically

100>V.

3. Standard microprocessor control signals to allow easy inter-

facing to most popular 8- and 16-bit microprocessors.

4. Monolithic construction for increased reliability and small

0.3", 24-pin package.

REV. B

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