4-Channel, ±10 V Input Range, High
Throughput, 24-Bit Sigma-Delta ADC
AD7734
Data Sheet
FEATURES
FUNCTIONAL BLOCK DIAGRAM
REFIN(–)
AIN0
REFIN(+)
REFERENCE
DETECT
AIN1
BUFFER
MUX
24-BIT
Σ-∆ ADC
AIN2
AIN3
AD7734
BIASHI
BIASLO
SCLK
CALIBRATION
CIRCUITRY
SERIAL
INTERFACE
DOUT
DIN
CS
P0
SYNC/P1
I/O PORT
CLOCK
GENERATOR
AGND AVDD MCLKOUT MCLKIN
CONTROL
LOGIC
DGND DVDD
RDY
RESET
03071-001
High resolution analog-to-digital converter (ADC)
24 bits no missing codes
±0.0025% nonlinearity
Optimized for fast channel switching
18-bit p-p resolution (21 bits effective) at 500 Hz
16-bit p-p resolution (19 bits effective) at 2 kHz
14-bit p-p resolution (18 bits effective) at 15 kHz
On-chip per channel system calibration
4 single-ended analog inputs
Input ranges +5 V, ±5 V, +10 V, ±10 V
Overvoltage tolerant
Up to ±16.5 V not affecting adjacent channel
Up to ±50 V absolute maximum
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
Figure 1.
APPLICATIONS
PLCs/DCS
Multiplexing applications
Process control
Industrial instrumentation
GENERAL DESCRIPTION
The AD7734 is a high precision, high throughput analog front
end. True 16-bit p-p resolution is achievable with a total conversion
time of 500 μs (2 kHz channel switching), making it ideally suitable
for high resolution multiplexing applications.
3-wire operation and is compatible with microcontrollers and
digital signal processors. All interface inputs are Schmitt triggered.
The device can be configured via a simple digital interface, which
allows users to balance the noise performance against data
throughput up to 15.4 kHz.
Other devices in the AD7734 family are the AD7732 and the
AD7738.
The 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 device has an overrange
and underrange detection capability and accepts an analog
input overvoltage to ±16.5 V without degrading the
performance of the adjacent channels.
The differential reference input features “No-Reference” detect
capability. The ADC also supports per channel system calibration options. The digital serial interface can be configured for
Rev. B
The device is specified for operation over the extended industrial
temperature range of –40°C to +105°C.
The AD7732 is similar to the AD7734, but its analog front end
features two fully differential input channels.
The AD7738 analog front end is configurable for four fully
differential or eight single-ended input channels, features
0.625 V to 2.5 V bipolar/unipolar input ranges, and accepts a
common-mode input voltage from 200 mV to AVDD – 300 mV.
The AD7738 multiplexer output is pinned out externally, allowing
the user to implement programmable gain or signal conditioning
before being applied to the ADC.
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