18-Bit, 1.25 MSPS PulSAR® ADC
AD7643
FUNCTIONAL BLOCK DIAGRAM
FEATURES
TEMP REFBUFIN REF REFGND
DVDD DGND
Throughput: 1.25 MSPS
INL: 1.5 LSB typical, 3 LSB maximum ( 11 ppm of full scale)
18-bit resolution with no missing codes
Dynamic range: 95 dB typical
AGND
AVDD
OVDD
OGND
AD7643
REF
REF AMP
SINAD: 93.5 dB typical @ 20 kHz (VREF = 2.5 V)
THD: −113 dB typical @ 20 kHz (VREF = 2.5 V)
2.048 V internal reference: typical drift 8 ppm/°C; TEMP output
Differential input range: VREF (VREF up to 2.5 V)
No pipeline delay (SAR architecture)
Parallel (18-, 16-, or 8-bit bus) and serial 5 V/3.3 V/2.5 V interface
SPI®/QSPI™/MICROWIRE™/DSP compatible
Single 2.5 V supply operation
SERIAL
PORT
18
IN+
IN–
SWITCHED
CAP DAC
D[17:0]
MODE0
MODE1
BUSY
RD
PARALLEL
INTERFACE
PDREF
PDBUF
PD
CLOCK
CONTROL LOGIC AND
CALIBRATION CIRCUITRY
CS
RESET
D0/OB/2C
Power dissipation
65 mW typical @ 1.25 MSPS with internal REF
2 μW in power-down mode
CNVST
Figure 1.
Pb-free, 48-lead LQFP and 48-lead LFCSP_VQ
Pin compatible with the AD7641 and other PulSAR ADC’s
Table 1. PulSAR 48-Lead Selection
100 to
250
500 to
570
650 to
1000
Type/kSPS
>1000
APPLICATIONS
Medical instruments
High speed data acquisition/high dynamic data acquisition
Pseudo
Differential
AD7651,
AD7660,
AD7661
AD7650,
AD7652,
AD7664,
AD7666
AD7653,
AD7667
Digital signal processing
Spectrum analysis
Instrumentation
Communications
ATE
True Bipolar
AD7610,
AD7663
AD7675
AD7665
AD7612,
AD7671
AD7677
True
Differential
AD7676
AD7621,
AD7622,
AD7623
AD7641,
AD7643
18-Bit
Multichannel/
Simultaneous
AD7631,
AD7678
AD7679
AD7654
AD7634,
AD7674
AD7655
GENERAL DESCRIPTION
The AD7643 is an 18-bit, 1.25 MSPS, charge redistribution
SAR, fully differential, analog-to-digital converter (ADC) 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 (and buffer), error correction circuits, and
both serial and parallel system interface ports. The part has no
latency and can be used in asynchronous rate applications. The
AD7643 is hardware factory calibrated and tested to ensure ac
parameters, such as signal-to-noise ratio (SNR), in addition to
the more traditional dc parameters of gain, offset, and linearity.
The AD7643 is only available in Pb-free packages with
PRODUCT HIGHLIGHTS
1. Fast Throughput.
The AD7643 is a 1.25 MSPS, charge redistribution,
18-bit SAR ADC.
2. Superior Linearity.
The AD7643 has no missing 18-bit code.
3. Internal Reference.
The AD7643 has a 2.048 V internal reference with a typical
drift of 8 ppm/°C and an on-chip TEMP sensor.
4. Single-Supply Operation.
operation specified from −40°C to +85°C.
The AD7643 operates from a 2.5 V single supply.
5. Serial or Parallel Interface.
Versatile parallel (18-, 16-, or 8-bit bus) or 2-wire serial
interface arrangement compatible with 2.5 V, 3.3 V, or
5 V logic.
Rev. 0
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rights of third parties that may result from its use. Specifications subject to change without notice. No
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