AD7949 Datasheet, PDF (1/28 Pages) Analog Devices – 14-Bit, 8-Channel, 250 kSPS PulSAR ADC

FEATURES
14-bit resolution with no missing codes
8-channel multiplexer with choice of inputs
Unipolar single ended
Differential (GND sense)
Pseudobipolar
Throughput: 250 kSPS
INL/DNL: ±0.5 LSB typical
SINAD: 85 dB @ 20 kHz
THD: 100 dB @ 20 kHz
Analog input range: 0 V to VREF with VREF up to VDD
Multiple reference types
Internal selectable 2.5 V or 4.096 V
External buffered (up to 4.096 V)
External (up to VDD)
Internal temperature sensor
Channel sequencer, selectable 1-pole filter, busy indicator
No pipeline delay, SAR architecture
Single-supply 2.7 V to 5.5 V operation with
1.8 V to 5 V logic interface
Serial interface compatible with SPI, MICROWIRE,
QSPI, and DSP
Power dissipation
2.9 mW @ 2.5 V/200 kSPS
10.8 mW @ 5 V/250 kSPS
Standby current: 50 nA
20-lead 4 mm × 4 mm LFCSP package
APPLICATIONS
Battery-powered equipment
Medical instruments: ECG/EKG
Mobile communications: GPS
Personal digital assistants
Power line monitoring
Data acquisition
Seismic data acquisition systems
Instrumentation
Process control
14-Bit, 8-Channel,
250 kSPS PulSAR ADC
AD7949
FUNCTIONAL BLOCK DIAGRAM
0.5V TO 4.096V
0.1µF
0.5V TO VDD
22µF
2.7V TO 5V
REFIN
REF
VDD
BAND GAP
REF
IN0
IN1
IN2
IN3
IN4
IN5
IN6
IN7
COM
TEMP
SENSOR
AD7949
MUX
16-BIT SAR SPI SERIAL
ADC
INTERFACE
ONE-POLE
LPF
SEQUENCER
GND
1.8V
VIO _TO
VDD
CNV
SCK
SDO
DIN
Figure 1.
Table 1. Multichannel 14-/16-Bit PulSAR® ADC
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 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 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 multi-
plexer 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 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.
Rev. A
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