
18-Bit, 2.5 LSB INL, 570 kSPS SAR ADC
AD7679
Rev. A
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FEATURES
18-bit resolution with no missing codes
No pipeline delay (SAR architecture)
Differential input range: ±VREF (VREF up to 5 V)
Throughput: 570 kSPS
INL: ±2.5 LSB max (±9.5 ppm of full scale)
Dynamic range : 103 dB typ (VREF = 5 V)
S/(N+D): 100 dB typ @ 2 kHz (VREF = 5 V)
Parallel (18-,16-, or 8-bit bus) and serial 5 V/3 V interface
SPI
/QSPI/MICROWIRE/DSP compatible
On-board reference buffer
Single 5 V supply operation
Power dissipation: 76 mW @ 500 kSPS
150 μW @ 1 kSPS
48-lead LQFP or 48-lead LFCSP package
Pin-to-pin compatible upgrade of AD7674/AD7676/AD7678
APPLICATIONS
CT scanners
High dynamic data acquisition
Geophone and hydrophone sensors
Σ-Δ replacement (low power, multichannel)
Instrumentation
Spectrum analysis
Medical instruments
FUNCTIONAL BLOCK DIAGRAM
SWITCHED
CAP DAC
18
CONTROL LOGIC AND
CALIBRATION CIRCUITRY
CLOCK
AD7679
D[17:0]
BUSY
RD
CS
MODE0
OGND
OVDD
DGND
DVDD
AVDD
AGND
REF REFGND
IN+
IN–
PD
RESET
SERIAL
PORT
PARALLEL
INTERFACE
CNVST
PDBUF
REFBUFIN
MODE1
03085–0–001
Figure 1. Functional Block Diagram
Table 1. PulSAR Selection
Type/kSPS
100–250
500–570
800–
1000
Pseudo-
Differential
True Bipolar
True
Differential
18-Bit
Multichannel/
Simultaneous
GENERAL DESCRIPTION
The AD7679 is an 18-bit, 570 kSPS, charge redistribution SAR,
fully differential analog-to-digital converter that operates on a
single 5 V power supply. The part contains a high speed 18-bit
sampling ADC, an internal conversion clock, an internal
reference buffer, error correction circuits, and both serial and
parallel system interface ports.
The part is available in a 48-lead LQFP or 48-lead LFCSP with
operation specified from –40°C to +85°C.
PRODUCT HGHLIGHTS
1.
High Resolution, Fast Throughput.
The AD7679 is a 570 kSPS, charge redistribution, 18-bit
SAR ADC (no latency).
2.
Excellent Accuracy.
The AD7679 has a maximum integral nonlinearity of
2.5 LSB with no missing 18-bit codes.
3.
Serial or Parallel Interface.
Versatile parallel (18-, 16-, or 8-bit bus) or 3-wire serial
interface arrangement compatible with both 3 V and
5 V logic.