24-Bit, 625 kSPS, 109 dB Sigma-Delta
ADC with On-Chip Buffers, Serial Interface
Data Sheet
Rev. B
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FEATURES
120 dB dynamic range at 78 kHz output data rate
109 dB dynamic range at 625 kHz output data rate
112 dB SNR at 78 kHz output data rate
107 dB SNR at 625 kHz output data rate
625 kHz maximum fully filtered output word rate
Programmable oversampling rate (32× to 256×)
Flexible serial interface
Fully differential modulator input
On-chip differential amplifier for signal buffering
Low-pass finite impulse response (FIR) filter with default
or user-programmable coefficients
Overrange alert bit
Digital offset and gain correction registers
Low power and power-down modes
Synchronization of multiple devices via SYNC pin
I2S interface mode
APPLICATIONS
Data acquisition systems
Vibration analysis
Instrumentation
FUNCTIONAL BLOCK DIAGRAM
05476-
00
1
AD7763
VIN+
VIN–
AVDD1
AGND
MCLK
DGND
VDRIVE
AVDD2
AVDD3
AVDD4
DVDD
DECAPA
RBIAS
DECAPB
MCLKGND
SYNC
RESET
SH2:0
ADR2:0
CDIV
I2
S
SC
P
SC
R
SDL
DRD
Y
SC
O
FSO
SD
O
SD
I
FS
I
CONTROL LOGIC
I/O
OFFSET AND GAIN
REGISTERS
DIFF
MULTIBIT
-
MODULATOR
RECONSTRUCTION
VREF+
REFGND
FIR FILTER
ENGINE
PROGRAMMABLE
DECIMATION
BUF
Figure 1.
GENERAL DESCRIPTION
converter (ADC) combines wide input bandwidth and high
speed with the benefits of Σ-Δ conversion, as well as performance
of 107 dB SNR at 625 kSPS, making it ideal for high speed data
acquisition. A wide dynamic range, combined with significantly
reduced antialiasing requirements, simplifies the design process.
An integrated buffer to drive the reference, a differential ampli-
fier for signal buffering and level shifting, an overrange flag,
internal gain and offset registers, and a low-pass, digital FIR
filter make the
AD7763 a compact, highly integrated data
acquisition device requiring minimal peripheral component
selection. In addition, the device offers programmable
decimation rates and a digital FIR filter, which can be user-
programmed to ensure that its characteristics are tailored for the
user’s application. Th
e AD7763 is ideal for applications demanding
high SNR without necessitating the design of complex, front-
end signal processing.
The differential input is sampled at up to 40 MSPS by an analog
modulator. The modulator output is processed by a series of
low-pass filters, the final filter having default or user-programmable
coefficients. The sample rate, filter corner frequencies, and
output word rate are set by a combination of the external clock
frequency and the configuration registers of the
AD7763.analog input range. With a 4 V reference, the analog input range
is ±3.2 V differential-biased around a common mode of 2 V.
This common-mode biasing can be achieved using the on-chip
differential amplifiers, further reducing the external signal
conditioning requirements.
Th
e AD7763 is available in an exposed paddle, 64-lead TQFP_EP
and is specified over the industrial temperature range from
40°C to +85°C.
Table 1. Related Devices
Part No.
Description
24-bit, 2.5 MSPS, 100 dB Σ-Δ, parallel interface
24-bit, 625 kSPS, 109 dB Σ-Δ, parallel interface