AD7641 Datasheet, PDF (1/24 Pages) Analog Devices – 18-Bit, 2 MSPS SAR ADC

Preliminary Technical Data
FEATURES
18-bit resolution with no missing codes
2.5V internal low drift refernce
Throughput:
2 MSPS (Warp mode)
1.5 MSPS (Normal mode)
INL: ±2 LSB typical
S/(N+D): 93 dB typical @ 100 kHz ( VREF = 2.5 V )
THD: −100 dB typical @ 100 kHz
Differential input range: ±VREF (VREF up to 2.5 V)
No pipeline delay ( SAR architecture )
Parallel (18-, 16-, or 8-bit bus)
Serial 5 V/3.3 V/2.5 V interface
SPI®/QSPI™/MICROWIRE™/DSP compatible
On-board low drift reference with buffer and
temperature sensor
Single 2.5 V supply operation
Power dissipation: 100 mW typical @ 2 MSPS
Power-down mode
48-LQFP and LFCSP packages
Speed upgrade of the AD7674
Pin-to-pin compatible with the AD7621
APPLICATIONS
Medical instruments
High dynamic data acquisition
Instrumentation
Spectrum analysis
ATE
GENERAL DESCRIPTION
The AD7641 is a 18-bit, 2 MSPS, charge redistribution SAR,
fully differential analog-to-digital converter that operates from
a single 2.5 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. It features a very high sampling
rate mode (Warp) and a fast mode (Normal) for asynchronous
conversion rate applications. The AD7641 is hardware factory
calibrated and comprehensively tested to ensure ac parameters
such as signal-to-noise ratio (SNR) and total harmonic
distortion (THD) in addition to the more traditional dc
parameters of gain, offset and linearity. Operation is specified
from −40°C to +85°C.
Rev. Pr E
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Specifications subject to change without notice. No license is granted by implication
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18-Bit, 2 MSPS SAR ADC
AD7641
FUNCTIONAL BLOCK DIAGRAM
TEMP
REF REFGND
DVDD DGND
AGND
AVDD
REFBUFIN
REF
AD7641
SERIAL
PORT
OVDD
OGND
IN+
IN-
PDREF
PDBUF
PD
RESET
SWITCHED
CAP DAC
CLOCK
CONTROL LOGIC AND
CALIBRATION CIRCUITRY
18
PARALLEL
INTERFACE
D[17:0]
BUSY
RD
CS
MODE0
MODE1
WARP IMPULSE CNVST
Figure 1.
Table 1. PulSAR Selection
kSPS
Type
800 to
100 to 250 500 to 570 1000
Pseudo
Differential
AD7651
AD7650/52 AD7653
AD7660/61 AD7664/66 AD7667
True Bipolar
AD7663
AD7665
AD7671
True Differential AD7675 AD7676 AD7677
18 Bit
AD7678
AD7679
AD7674
Multichannel/
Simultaneous
AD7654 AD7655
>1000
AD7621
AD7641
PRODUCT HIGHLIGHTS
1. High resolution and Fast Throughput.
The AD7641 is a 2 MSPS, charge redistribution, 18-bit
SAR ADC (no latency).
2. Superior INL.
The AD7641 has a maximum integral nonlinearity of
2 LSB with no missing 18-bit codes.
3. Single-Supply Operation.
Operates from a single 2.5 V supply. Also features a
power-down mode.
4. Serial or Parallel Interface.
Versatile parallel (18-, 16-, or 8-bit bus) or 2-wire
serial interface arrangement compatible with either
2.5 V, 3.3 V, or 5 V logic.
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