16-Bit, Isolated Sigma-Delta Modulator
Data Sheet
AD7403
FEATURES
FUNCTIONAL BLOCK DIAGRAM
V
V
DD1
DD2
5 MHz to 20 MHz external clock input rate
16 bits, no missing codes
Signal-to-noise ratio (SNR): 88 dB typical
Effective number of bits (ENOB): 14.2 bits typical
Offset drift vs. temperature
BUF
CLK
DECODER
CLK
ENCODER
MCLKIN
(5MHz
TO 20MHz)
REF
AD7403: 1.6 µV/°C typical
AD7403-8: 2 µV/°C typical
On-board digital isolator
V
V
IN+
Σ-Δ ADC
DATA
ENCODER
DATA
DECODER
IN–
MDAT
On-board reference
Full-scale analog input range: 320 mV
Operating range
AD7403
AD7403: −40°C to + 125°C
AD7403-8: −40°C to + 105°C
GND
GND
1
2
High common-mode transient immunity: >25 kV/µs
Wide-body SOIC with increased creepage package
Slew rate limited output for low EMI
Safety and regulatory approvals
UL recognition
Figure 1.
5000 V rms for 1 minute per UL 1577
CSA Component Acceptance Notice 5A
VDE Certificate of Conformity
DIN V VDE V 0884-10 (VDE V 0884-10):2006-12
V
IORM = 1250 VPEAK
APPLICATIONS
Shunt current monitoring
AC motor controls
Power and solar inverters
Wind turbine inverters
Data acquisition systems
Analog-to-digital and optoisolator replacements
information can be reconstructed with an appropriate digital
filter to achieve 88 dB signal to noise ratio (SNR) at 78.1 kSPS.
The serial input/output can use a 5 V or a 3 V supply (VDD2).
GENERAL DESCRIPTION
The AD74031 is a high performance, second-order, Σ-Δ modulator
that converts an analog input signal into a high speed, single-bit
data stream, with on-chip digital isolation based on Analog
Devices, Inc., iCoupler® technology. The device operates from a
5 V (VDD1) power supply and accepts a differential input signal
of 250 mV ( 320 mV full-scale). The differential input is ideally
suited to shunt voltage monitoring in high voltage applications
where galvanic isolation is required.
The serial interface is digitally isolated. High speed complementary
metal oxide semiconductor (CMOS) technology, combined with
monolithic transformer technology, means the on-chip isolation
provides outstanding performance characteristics, superior to
alternatives such as optocoupler devices. The AD7403 device is
offered in a 16-lead, wide-body SOIC package and has an oper-
ating temperature range of −40°C to +125°C. The AD7403-8
device is offered in an 8-lead, wide-body SOIC package and has
an operating temperature range of −40°C to +105°C.
The analog input is continuously sampled by a high performance
analog modulator, and converted to a ones density digital output
stream with a data rate of up to 20 MHz. The original
1 Protected by U.S. Patents 5,952,849; 6,873,065; and 7,075,329.
Rev. B
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