4-Channel, 1.5 MSPS, 12-Bit and 10-Bit

Parallel ADCs with a Sequencer

Preliminary Technical Data

AD7933/AD7934

FEATURES

Fast throughput rate: 1.5 MSPS

Low power

8 mW max at 1.5 MSPS with 3 V supplies

16 mW max at 1.5 MSPS with 5 V supplies

4 analog input channels with a sequencer

Software configurable analog inputs

4-channel single-ended inputs

2-channel fully differential inputs

2-channel pseudo-differential inputs

Accurate on-chip 2.5 V reference

Wide input bandwidth

70 dB SNR at 50 kHz input frequency

No pipeline delays

High speed parallel interface—word/byte modes

Full shutdown mode: 1 µA max

28 lead TSSOP package

FUNCTIONAL BLOCK DIAGRAM

T/H

PARALLEL INTERFACE/CONTROL REGISTER

SEQUENCER

12-/10-BIT

SAR ADC

AND

CONTROL

I/P

MUX

2.5V

VREF

DB0 DB11

AD7933/AD7934

AGND

CLKIN

BUSY

CONVST

CS

DGND

RD WR W/B

Figure 1.

GENERAL DESCRIPTION

The AD7933/AD7934 are 12-bit and 10-bit, high speed, low

power, successive approximation (SAR) ADCs. The parts

operate from a single 2.7 V to 5.25 V power supply and feature

throughput rates to 1.5 MSPS. The parts contain a low noise,

wide bandwidth, differential track-and-hold amplifier that can

handle input frequencies up to 20 MHz.

The AD7933/AD7934 feature 4 analog input channels with a

channel sequencer to allow a consecutive sequence of channels

to be converted on. These parts can accept either single-ended,

fully differential, or pseudo-differential analog inputs.

The conversion process and data acquisition are controlled

using standard control inputs, which allows for easy interfacing

to microprocessors and DSPs. The input signal is sampled on

the falling edge of CONVST and the conversion is also initiated

at this point.

The AD7933/AD7934 has an accurate on-chip 2.5 V reference

that can be used as the reference source for the analog-to-digital

conversion. Alternatively, this pin can be overdriven to provide

an external reference.

These parts use advanced design techniques to achieve very low

power dissipation at high throughput rates. They also feature

flexible power management options. An on-chip control register

allows the user to set up different operating conditions,

including analog input range and configuration, output coding,

power management, and channel sequencing.

PRODUCT HIGHLIGHTS

1.

High throughput with low power consumption.

2.

Four analog inputs with a channel sequencer.

3.

Accurate on-chip 2.5 V reference.

4.

Software configurable analog inputs. Single-ended, pseudo-

differential, or fully differential analog inputs that are

software selectable.

5.

function allows the parallel interface to connect directly to

6.

No pipeline delay.

7.

Accurate control of the sampling instant via a CONVST

input and once off conversion control.

PrG

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© 2004 Analog Devices, Inc. All rights reserved.

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