AD7400: Isolated Sigma-Delta Modulator 0 pages

Isolated Sigma-Delta Modulator
AD7400
Rev. C
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FEATURES
10 MHz clock rate
Second-order modulator
16 bits no missing codes
±2 LSB INL typical at 16 bits
3.5 ìV/°C maximum offset drift
On-board digital isolator
On-board reference
Low power operation: 18 mA maximum at 5.25 V
-40°C to +105°C operating range
16-lead SOIC package
Safety and regulatory approvals
UL recognition
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 = 891 V peak
APPLICATIONS
AC motor controls
Data acquisition systems
A/D + opto-isolator replacements
GENERAL DESCRIPTION
The AD74001 is a second-order, sigma-delta (Ó-Ä) modulator that converts an analog input signal to a high speed, 1-bit data stream with on-chip digital isolation based on Analog Devices, Inc. iCoupler® technology. The AD7400 operates from a 5 V power supply and accepts a differential input signal of ±200 mV (±320 mV full scale). The analog input is continuously sampled by the analog modulator, eliminating the need for external sample-and-hold circuitry. The input information is contained in the output stream as a density of ones with a data rate of 10 MHz. The original information can be reconstructed with an appropriate digital filter. The serial I/O can use a 5 V or a 3 V supply (VDD2).
The serial interface is digitally isolated. High speed CMOS, combined with monolithic air core transformer technology, means the on-chip isolation provides outstanding performance characteristics superior to alternatives such as optocoupler devices. The part contains an on-chip reference. The AD7400 is offered in a 16-lead SOIC and has an operating temperature range of -40°C to +105°C.
An external clock version, AD7401, is also available.
1 Protected by U.S. Patents 5,952,849; 6,873,065; and 7,075,329. Other patents pending.
FUNCTIONAL BLOCK DIAGRAM 04718-001VIN+VDD1VDD2VIN–Ó-Ä ADCCONTROL LOGICAD7400BUFT/HREFUPDATEGND1GND2MDATMCLKOUTENCODEENCODEDECODEDECODEWATCHDOGWATCHDOGUPDATE
Figure 1.