ANALOG DEVICES AD7949-EP Service Manual

14-Bit, 8-Channel,

AD7949-EP

REF

GND

VDD

VIO

DIN

SCK SDO

CNV

1.8V TO VDD

2.3V TO 5. 5V

SEQUENCER

SPI SERIAL INTERFACE

MUX

14-BIT SAR

ADC

BAND GAP

REF

TEMP

SENSOR

REFIN

IN0 IN1

IN4 IN5 IN6 IN7

IN3

IN2

COM

0.5V TO VDD

10µF

ONE-POLE

LPF

0.5V TO VDD – 0.5V

0.1µF

09822-001

FEATURES

14-bit resolution with no missing codes 8-channel multiplexer with choice of inputs

Throughput: 250 kSPS INL/DNL: ±0.5/±0.25 LSB typical SINAD: 85 dB @ 20 kHz THD: −100 dB @ 20 kHz Analog input range: 0 V to V Multiple reference types

Internal temperature sensor (TEMP) Channel sequencer, selectable 1-pole filter, busy indicator No pipeline delay, SAR architecture Single-supply 2.3 V to 5.5 V operation with

Serial interface compatible with SPI, MICROWIRE,

Power dissipation

Standby current: 50 nA 20-lead 4 mm × 4 mm LFCSP package Supports defense and aerospace applications (AQEC

Military temperature range (−55°C to +125°C) Controlled manufacturing baseline Enhanced product change notification Qualification data available on request

APPLICATIONS

Multichannel system monitoring Battery-powered equipment Medical instruments: ECG/EKG Mobile communications: GPS Power line monitoring Data acquisition Seismic data acquisition systems Instrumentation Process control

Rev. 0

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Unipolar single-ended Differential (GND sense) Pseudobipolar

with V

REF

Internal selectable 2.5 V or 4.096 V External buffered (up to 4.096 V) External (up to VDD)

1.8 V to 5.5 V logic interface

QSPI, and DSP

2.9 mW @ 2.5 V/200 kSPS

10.8 mW @ 5 V/250 kSPS

standard)

up to VDD

REF

250 kSPS PulSAR ADC

FUNCTIONAL BLOCK DIAGRAM

Figure 1.

Table 1. Multichannel 14-/16-Bit PulSAR® ADCs

Type Channels 250 kSPS 500 kSPS ADC Driver 14-Bit 8 AD7949 ADA4841-x 16-Bit 4 AD7682 ADA4841-x 16-Bit 8 AD7689 AD7699 ADA4841-x

GENERAL DESCRIPTION

The AD7949-EP is an 8-channel, 14-bit, charge redistribution successive approximation register (SAR) analog-to-digital converter (ADC) that operates from a single power supply, VDD.

The AD7949-EP contains all components for use in a multichannel, low power data acquisition system, including a true 14-bit SAR ADC with no missing codes; an 8-channel, low crosstalk multiplexer that is useful for configuring the inputs as single-ended (with or without ground sense), differential, or bipolar; an internal low drift reference (selectable 2.5 V or

4.096 V) and buffer; a temperature sensor; a selectable one-pole filter; and a sequencer that is useful when channels are continuously scanned in order.

The AD7949-EP uses a simple SPI interface for writing to the configuration register and receiving conversion results. The SPI interface uses a separate supply, VIO, which is set to the host logic level. Power dissipation scales with throughput.

The AD7949-EP is housed in a tiny 20-lead LFCSP with operation specified from −55°C to +125°C. Full details about this enhanced product are available in the AD7949 data sheet, which should be consulted in conjunction with this data sheet.

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