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 operation specified from −40°C to +85°C.

FEATURES
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: 95dB typical
SINAD: 93.5dB typical @ 20 kHz (VREF= 2.5 V)
THD: −113dB typical @ 20 kHz (VREF= 2.5 V)
2.048 V internal reference: typical drift 8ppm/°C; TEMP output
Differential input range: ±VREF(VREFup 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
Power dissipation
   65mW typical @ 1.25MSPS with internal REF
   2 μW in power-down mode
Pb-free, 48-lead LQFP and 48-lead LFCSP_VQ
Pin compatible with the AD7641and other PulSAR ADC’s

APPLICATIONS
Medical instruments
High speed data acquisition/high dynamic data acquisition
Digital signal processing
Spectrum analysis
Instrumentation
Communications
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