500 kSPS, 2-Channel, Software-Selectable,

True Bipolar Input, 12-Bit Plus Sign ADC

Data Sheet

AD7321

Rev. B

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FEATURES

12-bit plus sign SAR ADC

True bipolar input ranges

Software-selectable input ranges

±10 V, ±5 V, ±2.5 V, 0 V to +10 V

500 kSPS throughput rate

2 analog input channels with channel sequencer

Single-ended, true differential, and pseudo differential

analog input capability

High analog input impedance

Low power: 18 mW

Full power signal bandwidth: 22 MHz

Internal 2.5 V reference

High speed serial interface

Power-down modes

14-lead TSSOP package

i

CMOS™ process technology

FUNCTIONAL BLOCK DIAGRAM

DOUT

SCLK

CS

DIN

REFIN/OUT

AGND

DGND

CONTROL LOGIC

AND REGISTERS

13-BIT

SUCCESSIVE

APPROXIMATION

ADC

T/H

2.5V

VREF

I/P

MUX

CHANNEL

SEQUENCER

AD7321

Figure 1.

GENERAL DESCRIPTION

The AD73211 is a 2-channel, 12-bit plus sign successive

approximation ADC designed on the iCMOS (industrial

CMOS) process. iCMOS is a process combining high voltage

silicon with submicron CMOS and complementary bipolar

technologies. It enables the development of a wide range of high

performance analog ICs capable of 33 V operation in a footprint

that no previous generation of high voltage parts could achieve.

Unlike analog ICs using conventional CMOS processes, iCMOS

components can accept bipolar input signals while providing

increased performance, dramatically reduced power consumption,

and reduced package size.

The AD7321 can accept true bipolar analog input signals. The

AD7321 has four software-selectable input ranges, ±10 V, ±5 V,

±2.5 V, and 0 V to +10 V. Each analog input channel is indepen-

dently programmed to one of the four input ranges. The analog

input channels on the AD7321 are programmed to be single-ended,

true differential, or pseudo differential.

The ADC contains a 2.5 V internal reference. The AD7321 also

allows for external reference operation. If a 3 V reference is applied

to the REFIN/OUT pin, the AD7321 can accept a true bipolar

are required for the ±12 V input range. The ADC has a high speed

serial interface that can operate at throughput rates up to 500 kSPS.

PRODUCT HIGHLIGHTS

1. The AD7321 can accept true bipolar analog input signals,

±10 V, ±5 V, ±2.5 V, and 0 V to +10 V unipolar signals.

2. The two analog inputs are configured as two single-ended

inputs, one true differential input pair, or one pseudo

differential input.

3. A 500 kSPS serial interface. SPI®-/QSPI™-/DSP-/

MICROWIRE™-compatible interface.

4. Low power, 18 mW, at a maximum throughput rate of

500 kSPS.

5. Channel sequencer.

Table 1. Similar Devices

Device

Number

Throughput

Rate

Number of bits

Number of

Channels

AD7329

1000 kSPS

12-bit plus sign

8

AD7328

1000 kSPS

12-bit plus sign

8

AD7327

500 kSPS

12-bit plus sign

8

AD7324

1000 kSPS

12-bit plus sign

4

AD7323

500 kSPS

12-bit plus sign

4

AD7322

1000 kSPS

12-bit plus sign

2

1

Protected by U.S. Patent No. 6,731,232.