AD7738BRUZ-REEL7 Datasheet, PDF (1/28 Pages) Analog Devices – 8-Channel, High Throughput 24-Bit ADC

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FEATURES
High Resolution ADC
24 Bits No Missing Codes
؎0.0015% Nonlinearity
Optimized for Fast Channel Switching
18-Bits p-p Resolution (21 Bits Effective) at 500 Hz
16-Bits p-p Resolution (19 Bits Effective) at 8.5 kHz
15-Bits p-p Resolution (18 Bits Effective) at 15 kHz
On-Chip Per Channel System Calibration
Configurable Inputs
8 Single-Ended or 4 Fully Differential
Input Ranges
+625 mV, +1.25 V, +2.5 V, ؎625 mV, ؎1.25 V, ؎2.5 V
3-Wire Serial Interface
SPI™, QSPI™, MICROWIRE™ and DSP Compatible
Schmitt Trigger on Logic Inputs
Single-Supply Operation
5 V Analog Supply
3 V or 5 V Digital Supply
Package: 28-Lead TSSOP
APPLICATIONS
PLCs/DCS
Multiplexing Applications
Process Control
Industrial Instrumentation
8-Channel, High Throughput,
24-Bit ⌺-⌬ ADC
AD7738
FUNCTIONAL BLOCK DIAGRAM
MUXOUT ADCIN
REFIN– REFIN+
AIN0
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
AINCOM/P0
MUX
REFERENCE
DETECT
BUFFER
24-BIT
⌺-⌬ ADC
AD7738
CALIBRATION
CIRCUITRY
SERIAL
INTERFACE
SCLK
DOUT
DIN
CS
SYNC/P1
I/O PORT
CLOCK
GENERATOR
CONTROL
LOGIC
RDY
RESET
AGND AV_DD MCLKOUT MCLKIN DGND DV_DD
GENERAL DESCRIPTION
The AD7738 is a high precision, high throughput analog front
end. True 16-bit p-p resolution is achievable with a total con-
version time of 117 µs (8.5 kHz channel switching), making it
ideally suitable for high resolution multiplexing applications.
The part can be configured via a simple digital interface, which
allows users to balance the noise performance against data
throughput up to a 15.4 kHz.
The analog front end features eight single-ended or four fully
differential input channels with unipolar or bipolar 625 mV,
1.25 V, and 2.5 V input ranges and accepts a common-mode
input voltage from 200 mV above AGND to AV_DD – 300 mV.
The multiplexer output is pinned out externally, allowing the
user to implement programmable gain or signal conditioning
before applying the input to the ADC.
SPI and QSPI are trademarks of Motorola, Inc.
MICROWIRE is a trademark of National Semiconductor Corporation
REV. 0
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. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
The differential reference input features “No-Reference” detect
capability. The ADC also supports per channel system calibra-
tion options.
The digital serial interface can be configured for 3-wire opera-
tion and is compatible with microcontrollers and digital signal
processors. All interface inputs are Schmitt triggered.
The part is specified for operation over the extended industrial
temperature range of –40؇C to +105؇C.
Other parts in the AD7738 family are the AD7734 and the
AD7732.
The AD7734 analog front end features four single-ended input
channels with unipolar or true bipolar input ranges to ± 10 V
while operating from a single 5 V analog supply. The AD7734
accepts an analog input overvoltage to ± 16.5 V while not
degrading the performance of the adjacent channels.
The AD7732 is similar to AD7734, but its analog front end
features two fully differential input channels.
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© Analog Devices, Inc., 2002