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AD7400: Isolated Sigma-Delta Modulator

AD7400: Isolated Sigma-Delta Modulator
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AD7400: Isolated Sigma-Delta Modulator - 1

Isolated Sigma-Delta Modulator AD7400 Rev. C 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. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2006–2011 Analog Devices, Inc. All rights reserved. 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.

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AD7400: Isolated Sigma-Delta Modulator - 3

AD7400 Rev. C | Page 3 of 20 SPECIFICATIONS VDD1 = 4.5 V to 5.25 V, VDD2 = 3 V to 5.5 V, VIN+ = -200 mV to +200 mV, and VIN- = 0 V (single-ended); TA = TMIN to TMAX, fMCLK = 10 MHz, tested with Sinc3 filter, 256 decimation rate, as defined by Verilog code, unless otherwise noted.1 Table 1. Parameter Y Version1, 2 Unit Test Conditions/Comments STATIC PERFORMANCE Resolution 16 Bits min Filter output truncated to 16 bits Integral Nonlinearity3 ±15 LSB max -40°C to +85°C; ±2 LSB typical ±25 LSB max >85°C to 105°C Differential Nonlinearity3 ±0.9 LSB max Guaranteed no missing codes to 16 bits...

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AD7400: Isolated Sigma-Delta Modulator - 4

AD7400 Rev. C | Page 4 of 20 TIMING SPECIFICATIONS VDD1 = 4.5 V to 5.25 V, VDD2 = 3 V to 5.5 V, TA = TMAX to TMIN, unless otherwise noted.1 Table 2. Parameter Limit at TMIN, TMAX Unit Description fMCLKOUT2 10 MHz typ Master clock output frequency 9/11 MHz min/MHz max Master clock output frequency t13 40 ns max Data access time after MCLK rising edge t23 10 ns min Data hold time after MCLK rising edge t3 0.4 × tMCLKOUT ns min Master clock low time t4 0.4 × tMCLKOUT ns min Master clock high time 1 Sample tested during initial release to ensure compliance. 2 Mark space ratio for clock output...

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AD7400: Isolated Sigma-Delta Modulator - 5

AD7400 Rev. C | Page 5 of 20 INSULATION AND SAFETY-RELATED SPECIFICATIONS Table 3. Parameter Symbol Value Unit Conditions Input-to-Output Momentary Withstand Voltage VISO 5000 min V rms 1-minute duration Minimum External Air Gap (Clearance) L(I01) 7.46 min mm Measured from input terminals to output terminals, shortest distance through air Minimum External Tracking (Creepage) L(I02) 8.1 min mm Measured from input terminals to output terminals, shortest distance path along body Minimum Internal Gap (Internal Clearance) 0.017 min mm Insulation distance through insulation Tracking Resistance...

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AD7400: Isolated Sigma-Delta Modulator - 6

AD7400 Rev. C | Page 6 of 20 DIN V VDE V 0884-10 (VDE V 0884-10) INSULATION CHARACTERISTICS This isolator is suitable for reinforced electrical isolation only within the safety limit data. Maintenance of the safety data is ensured by means of protective circuits. Table 5. Description Symbol Characteristic Unit INSTALLATION CLASSIFICATION PER DIN VDE 0110 For Rated Mains Voltage 300 V rms I–IV For Rated Mains Voltage 450 V rms I–II For Rated Mains Voltage 600 V rms I–II CLIMATIC CLASSIFICATION 40/105/21 POLLUTION DEGREE (DIN VDE 0110, Table 1) 2 MAXIMUM WORKING INSULATION VOLTAGE VIORM 891 V...

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AD7400: Isolated Sigma-Delta Modulator - 7

AD7400 Rev. C | Page 7 of 20 ABSOLUTE MAXIMUM RATINGS TA = 25°C, unless otherwise noted. All voltages are relative to their respective ground. Table 6. Parameter Rating VDD1 to GND1 -0.3 V to +6.5 V VDD2 to GND2 -0.3 V to +6.5 V Analog Input Voltage to GND1 -0.3 V to VDD1 + 0.3 V Output Voltage to GND2 -0.3 V to VDD2 + 0.3 V Input Current to Any Pin Except Supplies1 ±10 mA Operating Temperature Range -40°C to +105°C Storage Temperature Range -65°C to +150°C Junction Temperature 150°C SOIC Package èJA Thermal Impedance 89.2°C/W èJC Thermal Impedance 55.6°C/W Resistance (Input-to-Output),...

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AD7400: Isolated Sigma-Delta Modulator - 8

AD7400 Rev. C | Page 8 of 20 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 04718-004NC = NO CONNECTAD7400TOP VIEW(Not to Scale)VDD1VDD2VIN+VIN–GND2GND2VDD1GND1123NC4NC5NCMCLKOUTNC161514NC678MDATNC111091312 Figure 5. Pin Configuration Table 8. Pin Function Descriptions Pin No. Mnemonic Description 1, 7 VDD1 Supply Voltage. 4.5 V to 5.25 V. This is the supply voltage for the isolated side of the AD7400 and is relative to GND1. 2 VIN+ Positive Analog Input. Specified range of ±200 mV. 3 VIN- Negative Analog Input. Normally connected to GND1. 4 to 6, 10, 12, 15 NC No Connect. 8 GND1 Ground 1....

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