AD7643

Rev. 0

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FEATURES

Throughput: 1.25 MSPS

INL: ±1.5 LSB typical, ±3 LSB maximum (±11 ppm of full scale)

18-bit resolution with no missing codes

Dynamic range: 95 dB typical

2.048 V internal reference: typical drift 8 ppm/°C; TEMP output

No pipeline delay (SAR architecture)

Parallel (18-, 16-, or 8-bit bus) and serial 5 V/3.3 V/2.5 V interface

SPI®/QSPI™/MICROWIRE™/DSP compatible

Single 2.5 V supply operation

Power dissipation

65 mW typical @ 1.25 MSPS with internal REF

2 μW in power-down mode

Pb-free, 48-lead LQFP and 48-lead LFCSP_VQ

Pin compatible with the AD7641 and other PulSAR ADC’s

APPLICATIONS

Medical instruments

High speed data acquisition/high dynamic data acquisition

Digital signal processing

Spectrum analysis

Instrumentation

Communications

ATE

GENERAL DESCRIPTION

The AD7643 is an 18-bit, 1.25 MSPS, charge redistribution

SAR, fully differential, analog-to-digital converter (ADC) that

operates from a single 2.5 V power supply. The part contains a

high speed, 18-bit sampling ADC, an internal conversion clock,

an internal reference (and buffer), error correction circuits, and

both serial and parallel system interface ports. The part has no

latency and can be used in asynchronous rate applications. The

AD7643 is hardware factory calibrated and tested to ensure ac

parameters, such as signal-to-noise ratio (SNR), in addition to

the more traditional dc parameters of gain, offset, and linearity.

The AD7643 is only available in Pb-free packages with

operation specified from −40°C to +85°C.

FUNCTIONAL BLOCK DIAGRAM

18

CONTROL LOGIC AND

CALIBRATION CIRCUITRY

CLOCK

AD7643

DGND

DVDD

AVDD

AGND

REF REFGND

IN+

IN–

PD

RESET

PDBUF

REFBUFIN

PDREF

REF

TEMP

D[17:0]

BUSY

RD

CS

D0/OB/2C

OGND

OVDD

MODE1

MODE0

REF AMP

CNVST

SERIAL

PORT

PARALLEL

INTERFACE

SWITCHED

CAP DAC

Figure 1.

Table 1. PulSAR 48-Lead Selection

Type/kSPS

100 to

250

500 to

570

650 to

1000

>1000

Pseudo

Differential

AD7651,

AD7660,

AD7661

AD7650,

AD7652,

AD7664,

AD7666

AD7653,

AD7667

True Bipolar

AD7610,

AD7663

AD7665

AD7612,

AD7671

True

Differential

AD7675

AD7676

AD7677

AD7621,

AD7622,

AD7623

18-Bit

Multichannel/

AD7631,

AD7678

AD7679

AD7634,

AD7674

AD7641,

AD7643

Simultaneous

AD7654

AD7655

PRODUCT HIGHLIGHTS

1.

Fast Throughput.

The AD7643 is a 1.25 MSPS, charge redistribution,

18-bit SAR ADC.

2.

Superior Linearity.

The AD7643 has no missing 18-bit code.

3.

Internal Reference.

The AD7643 has a 2.048 V internal reference with a typical

drift of ±8 ppm/°C and an on-chip TEMP sensor.

4.

Single-Supply Operation.

The AD7643 operates from a 2.5 V single supply.

5.

Serial or Parallel Interface.

Versatile parallel (18-, 16-, or 8-bit bus) or 2-wire serial

interface arrangement compatible with 2.5 V, 3.3 V, or

5 V logic.