16-Bit, Isolated Sigma-Delta Modulator
10 MHz internal clock rate
16 bits, no missing codes
Signal-to-noise ratio (SNR): 87 dB typical
Effective number of bits (ENOB): 13.5 bits typical
Typical offset drift vs. temperature: 1.7 µV/°C
On-board digital isolator
Full-scale analog input range: ±320 mV
−40°C to +105°C operating range
High common-mode transient immunity: >25 kV/µs
8-lead, wide-body SOIC, with increased creepage package
Slew rate limited output for low electromagnetic
Safety and regulatory approvals
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
VIORM = 1250 VPEAK
Shunt current monitoring
AC motor controls
Power and solar inverters
Wind turbine inverters
Data acquisition systems
Analog-to-digital and opto-isolator replacements
The AD74021 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 AD7402 operates from
a 4.5 V to 5.5 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 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 10 MHz. The original
FUNCTIONAL BLOCK DIAGRAM
REF BUF CLOCK
information can be reconstructed with an appropriate digital
filter to achieve 87 dB signal to noise ratio (SNR) at 39 kSPS. The
serial input/output can use a 3 V to 5.5 V or a 3.3 V supply (VDD2).
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 AD7402 device is
offered in an 8-lead, wide body SOIC package and has an
operating temperature range of −40°C to +105°C.
1 Protected by U.S. Patents 5,952,849; 6,873,065; and 7,075,329.
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