Datasheet AD7949 (Analog Devices)

14-Bit, 8-Channel, 250 kSPS PulSAR ADC Data Sheet AD7949 FEATURES FUNCTIONAL BLOCK DIAGRAM 14-bit resolution with no missing codes 0.5V TO VDD – 0.5V 0.5V TO VDD 2.3V TO 5.5V 0.1µF 10µF 8-channel multiplexer with choice of inputs Unipolar single-ended REFIN REF VDD Differential (GND sense) 1.8V BAND GAP Pseudobipolar VIO TO REF AD7949 VDD Throughput: 250 kSPS TEMP INL/DNL: ±0.5/±0.25 LSB typical SENSOR SINAD: 85 dB @ 20 kHz IN0 CNV IN1 THD: −100 dB @ 20 kHz SCK IN2 SPI SERIAL MUX 14-BIT SAR IN3 ADC INTERFACE Analog input range: 0 V to V SDO REF with VREF up to VDD IN4 IN5 ONE-POLE DIN Multiple reference types IN6 LPF SEQUENCER Internal selectable 2.5 V or 4.096 V IN7 External buffered (up to 4.096 V) COM
001
External (up to VDD) GND
07351-
Internal temperature sensor (TEMP)
Figure 1.
Channel sequencer, selectable 1-pole filter, busy indicator No pipeline delay, SAR architecture Table 1. Multichannel 14-/16-Bit PulSAR® ADCs Single-supply 2.3 V to 5.5 V operation with Type Channels 250 kSPS 500 kSPS ADC Driver 1.8 V to 5.5 V logic interface
14-Bit 8 AD7949 ADA4841-1
Serial interface compatible with SPI, MICROWIRE,
16-Bit 4 AD7682 ADA4841-1
QSPI, and DSP
16-Bit 8 AD7689 AD7699 ADA4841-1
Power dissipation 2.9 mW @ 2.5 V/200 kSPS GENERAL DESCRIPTION 10.8 mW @ 5 V/250 kSPS
The AD7949 is an 8-channel, 14-bit, charge redistribution
Standby current: 50 nA
successive approximation register (SAR) analog-to-digital
20-lead 4 mm × 4 mm LFCSP package
converter (ADC) that operates from a single power supply, VDD.
APPLICATIONS
The AD7949 contains all components for use in a multichannel,
Multichannel system monitoring
low power data acquisition system, including a true 14-bit SAR
Battery-powered equipment
ADC with no missing codes; an 8-channel, low crosstalk
Medical instruments: ECG/EKG
multiplexer that is useful for configuring the inputs as single-
Mobile communications: GPS
ended (with or without ground sense), differential, or bipolar;
Power line monitoring
an internal low drift reference (selectable 2.5 V or 4.096 V) and
Data acquisition
buffer; a temperature sensor; a selectable one-pole filter; and a
Seismic data acquisition systems
sequencer that is useful when channels are continuously
Instrumentation
scanned in order.
Process control
The AD7949 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 is housed in a tiny 20-lead LFCSP with operation specified from −40°C to +85°C.
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION REVISION HISTORY SPECIFICATIONS TIMING SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TERMINOLOGY THEORY OF OPERATION OVERVIEW CONVERTER OPERATION TRANSFER FUNCTIONS TYPICAL CONNECTION DIAGRAMS Unipolar or Bipolar Bipolar Single Supply ANALOG INPUTS Input Structure Selectable Low-Pass Filter Input Configurations Sequencer Source Resistance DRIVER AMPLIFIER CHOICE VOLTAGE REFERENCE OUTPUT/INPUT Internal Reference/Temperature Sensor External Reference and Internal Buffer External Reference Reference Decoupling POWER SUPPLY SUPPLYING THE ADC FROM THE REFERENCE DIGITAL INTERFACE READING/WRITING DURING CONVERSION, FAST HOSTS READING/WRITING AFTER CONVERSION, ANY SPEED HOSTS READING/WRITING SPANNING CONVERSION, ANY SPEED HOST CONFIGURATION REGISTER, CFG GENERAL TIMING WITHOUT A BUSY INDICATOR GENERAL TIMING WITH A BUSY INDICATOR CHANNEL SEQUENCER Examples READ/WRITE SPANNING CONVERSION WITHOUT A BUSY INDICATOR READ/WRITE SPANNING CONVERSION WITH A BUSY INDICATOR APPLICATION HINTS LAYOUT EVALUATING AD7949 PERFORMANCE OUTLINE DIMENSIONS ORDERING GUIDE