16-Bit, 1.2 MSPS CMOS,
Sigma-Delta ADC
AD7723
16-bit Σ-∆ ADC
1.2 MSPS output word rate
32×/16× oversampling ratio
Low-pass and band-pass digital filter
Linear phase
On-chip 2.5 V voltage reference
Standby mode
Flexible parallel or serial interface
Crystal oscillator
Single 5 V supply
GENERAL DESCRIPTION
The AD7723 is a complete 16-bit, sigma-delta ADC. The part
operates from a 5 V supply. The analog input is continuously
sampled, eliminating the need for an external sample-and-hold.
The modulator output is processed by a finite impulse response
(FIR) digital filter. The on-chip filtering combined with a high
oversampling ratio reduces the external antialias requirements
to first order in most cases. The digital filter frequency response
can be programmed to be either low-pass or band-pass.
The AD7723 provides 16-bit performance for input bandwidths
up to 460 kHz at an output word rate up to 1.2 MHz. The
sample rate, filter corner frequencies, and output word rate are
set by the crystal oscillator or external clock frequency.
Data can be read from the device in either serial or parallel
format. A stereo mode allows data from two devices to share a
single serial data line. All interface modes offer easy, high speed
connections to modern digital signal processors.
FUNCTIONAL BLOCK DIAGRAM
AVDD
2.5V
REFERENCE
AD7723
AGND
VIN(+)
VIN(–)
MODULATOR
FIR
FILTER
UNI
HALF_PWR
STBY
MODE 1
MODE 2
SYNC
DVDD/ CS
CFMT/RD
DGND/DRDY
DGND/DB0
REF2
REF1
DVDD
DGND
XTAL
CLOCK
XTAL_OFF
XTAL
CLKIN
DGND/DB15
DGND/DB14
CONTROL
LOGIC
SCR/DB13
SLDR/DB12
SLP/DB11
TSI/DB10
FSO/DB9
DGND/ DGND/ DGND/ DOE/ SFMT/ FSI/ SCO/ SDO/
DB1
DB2 DB3 DB4 DB5 DB6 DB7 DB8
Figure 1.
The part provides an on-chip 2.5 V reference. Alternatively, an
external reference can be used.
A power-down mode reduces the idle power consumption
to 200 µW.
The AD7723 is available in a 44-lead MQFP package and is
specified over the industrial temperature range from
–40°C to +85°C.
Two input modes are provided, allowing both unipolar and
bipolar input ranges.
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other rights of third parties that may result from its use.
Specifications subject to change without notice. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices. Trademarks and
registered trademarks are the property of their respective owners.
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Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2005 Analog Devices, Inc. All rights reserved.
01186-001
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