AD7764 Datasheet, PDF (1/21 Pages) Analog Devices – 24-Bit 312 kSPS 109dB ADC With On-Chip Buffers Serial Interface

Preliminary Technical Data
24-Bit, 312 kSPS,109dB Σ∆ ADC,
With On-Chip Buffers, Serial Interface
AD7764
FEATURES
High performance 24-bit Sigma-Delta ADC
112dB SNR at 78kHz output data rate
106dB SNR at 312 kHz output data rate
312 kHz maximum fully filtered output word rate
Pin-selectable over-sampling rate (64x to 256x)
Flexible SPI serial interface
Fully differential modulator input
On-chip differential amplifier for signal buffering
On-chip Reference Buffer
Low pass FIR filter
Over-range alert pin
Digital gain correction registers
Power down mode
Synchronization of multiple devices via SYNC pin
Daisy Chaining
FUNCTIONAL BLOCK DIAGRAM
VOUTA- VOUTA+ VIN+ VIN-
MCLK
VINA+
VINA-
VREF+
REFGND
SYNC
RESET/PWRDN
DIFF
+
B_ UF
AD7764
Interface Logic
and
Offset & Gain Correction
Registers
Multi-Bit
Sigma-Delta
Modulator
Reconstruction
Decimation
FIR Filter
Engine
AVDD1
AVDD2
AVDD3
AVDD3
DVDD
OVERRANGE
DEC_RATE
DECAP
RBIAS
Figure 1.
APPLICATIONS
Data acquisition systems
Vibration analysis
Instrumentation
PRODUCT OVERVIEW
The AD7764 high performance, 24-bit, sigma delta analog to
digital converter combines wide input bandwidth, high speed
and performance of 109dB at a 312Khz output data rate with
the benefits of sigma delta conversion, while, also offering
excellent DC specifications which make the converter ideal for
high speed data acquisition of AC signals where DC data is also
a requirement.
A wide dynamic range combined with significantly reduced
anti-aliasing requirements simplifies the design process. The
AD7764 offers pin-selectable decimation rates of 64x, 128x,
and 256x. Other features include an integrated buffer to drive
the reference, a differential amplifier for signal buffering and
level shifting.
The addition of an internal gain register, an over-range alert
pin, and a low-pass digital FIR filter make the AD7764 a
compact highly integrated data acquisition device requiring
minimal peripheral component selection. The AD7764 is
ideally suited to applications demanding high SNR without
necessitating design of complex front end signal processing.
The differential input is sampled at up to 40MS/s by an analog
modulator. The modulator output is processed by a series of
low-pass filters. The sample rate, filter corner frequencies and
output word rate are determined by the external clock
frequency supplied to the AD7764.
The reference voltage supplied to the AD7764 determines the
analog input range. With a 4V reference, the analog input range
is ±3.2V differential biased around a common mode of 2V. This
common mode biasing can be achieved using the on-chip
differential amplifiers, further reducing the external signal
conditioning requirements.
The AD7764 is available in a 28-lead TSSOP package and is
specified over the industrial temperature range from -40°C to
+85°C
RELATED DEVICES
Part no.
AD7760
AD7762
AD7763
AD7765
Description
24-bit, 2.5MSPS, 100dB Σ∆, parallel interface
24-bit, 625ksps, 109dB Σ∆, parallel interface
24-bit, 625ksps, 109dB Σ∆, serial interface
24-bit, 156kSPS, 109dB Σ∆, serial interface
Rev. PrC
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