AD7761 datasheet(31/76 Pages) AD

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AD7761

Data Sheet

Rev. A | Page 30 of 75

APPLICATIONS INFORMATION

The AD7761 offers users a multichannel platform measurement

solution for ac and dc signal processing.

Flexible filtering allows the AD7761 to be configured to

simultaneously sample ac and dc signals on a per channel basis.

Power scaling allows users to trade off the input bandwidth of

the measurement vs. the current consumption. This ability,

coupled with the flexibility of the digital filtering, allows the

user to optimize the energy efficiency of the measurement,

while still meeting power, bandwidth, and performance targets.

Key capabilities that allow users to choose the AD7761 as their

platform high resolution ADC are highlighted as follows:

•

Eight fully differential or pseudo differential analog inputs.

•

Fast throughput simultaneous sampling ADCs catering for

input signals up to 110.8 kHz.

•

Three selectable power modes (fast, median, and low

power) for scaling the current consumption and input

bandwidth of the ADC for optimal measurement

efficiency.

•

Analog input precharge and reference precharge buffers

reduce the drive requirements of external amplifiers.

•

Control of reference and analog input precharge buffers on

a per channel basis.

•

Wideband, low ripple, digital filter for ac measurement.

•

Fast sinc5 filter for precision low frequency measurement.

•

Two channel modes, defined by the user selected filter choice,

and decimation ratios, can be defined for use on different

ADC channels. This enables optimization of the input

bandwidth versus the signal of interest.

•

Option of SPI or pin strapped control and configuration.

•

Offset, gain, and phase calibration registers per channel.

•

Common-mode voltage output buffer for use by a driver

amplifier.

•

On-board AVDD2 and IOVDD LDOs for the low power,

1.8 V, internal circuitry.

Refer to Figure 48 and Table 12 for the typical connections

and minimum requirements to get started using the AD7761.

Table 13 shows the typical power and performance of the

AD7761 for the available power modes, for each filter type.

ADC

DATA

SERIAL

INTERFACE

SPI

CONTROL

INTERFACE

VOUT

VIN

ADR4540

AVDD1A,

AVDD1B

AVSS

AVDD2A,

AVDD2B

REGCAPA,

REGCAPB

PRECHARGE

BUFFERS

AIN7+

AIN7–

AIN0+

AIN0–

VCM

AD7761

DREGCAP

IOVDD

REFx–

REFx+

ADA4940-1/

ADA4940-2

Σ-Δ

ADC

SINC5

LOW LATENCY FILTER

WIDEBAND

LOW RIPPLE FILTER

SYNC_IN

DRDY

SYNC_OUT

START

RESET

FORMATx

DCLK

DOUT6

DOUT7

ST0/CS

ST1/SCLK

DEC0/SDO

DEC1/SDI

FILTER/GPIO4

MODE3/GPIO3

MODE0/GPIO0

XTAL2/MCLK

XTAL1

PIN/SPI

DOUT0

DOUT1

DOUT2

DOUT3

DOUT4

DOUT5

ADA4841-1

–

SUGGESTED OP AMPS:

FAST MODE: ADA4896-2 OR ADA4807-2

MEDIAN MODE: ADA4940-2 OR ADA4807-2

LOW POWER MODE: ADA4805-2

Figure 48. Typical Connection Diagram

AD7761 Datasheet(PDF) 31 Page - Analog Devices

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