Designers of multichannel current and voltage monitoring systems deal with a complex host of circuit design challenges, such as dual supply requirements, limited analog input range, input impedance dependent on speed, and high costs due to implementation of expensive discrete components.

The AD7606 ADC simplifies substation automation design with its 8-channel, 16-bit, simultaneously sampling, true bipolar inputs. Integrating multiple channels enables the measurement of three-phase current, voltage, and neutral monitoring for substation automation equipment. The ±5 V and ±10 V input ranges allow for the preservation of phase information while sampling bipolar voltages and currents over a wide dynamic range. The AD7606's bipolar input capability from a single 5 V supply, high impedance analog inputs, and on-board reference eliminate the need for external components and allow for single supply systems.

This ADC, combined with other system components, provides a complete power line monitoring solution for multichannel systems, as shown in the diagram below. The AD7606 family is capable of achieving a sampling rate of up to 200 kSPS per channel. The part contains low noise, high impedance inputs (independent of sample rate), and signal scaling amplifiers that can handle input frequencies of up to 10 kHz. The AD7606 features a front-end antialiasing filter with attenuation of approximately 40 dB at 100 kHz input frequency. The conversion process and data acquisition are controlled using CONVST signals and an internal oscillator. Two CONVST pins allow the simultaneous sampling of all eight analog inputs or two groups of four analog input channels to allow for phase differences between transformers. Both high speed parallel and serial interface modes are available. The AD7606 SNR performance is 90 dB with the optional use of oversampling mode to further improve SNR performance, reduce code spread, and enhance antialias rejection.

The 16-bit AD7606 is available in 8-, 6-, and 4-channel versions; a 14-bit version with the same options is found in AD7607.

AD7606 Features

• 8/6/4 simultaneously sampled inputs
• True bipolar analog input ranges: ±10 V, ±5 V
• Single 5 V analog supply, 1.8 V to 5 V_DRIVE
• 1 MΩ analog input impedance
• Analog input clamp protection
• Fast throughput rate: up to 200 kSPS
• Low power: 100 mW typical at 200 kSPS
• 0.1% gain and 0.01% offset error

Highest Accuracy 3 V to 5 V Digital Variable Resistors Save Space in Tiny 3 mm × 3 mm LFCSP (SON) Package

The AD5270/AD5271/AD5272/AD5274 members of ADI's DigiPOT+™ family of digital variable resistors are single-channel, 1024-/256-position digitally controlled resistors with less than 1% end-to-end resistor tolerance error and 50-time programmable memory. The devices perform the same electronic adjustment function as a mechanical rheostat with enhanced resolution, solid state reliability, and superior low temperature coefficient performance. These devices are well-suited for high precision applications across industrial, communications, and consumer markets.

The AD527x digital potentiometers offer guaranteed industryleading low resistor tolerance errors of ±1% with a nominal temperature coefficient of 35 ppm/°C. The low resistor tolerance feature simplifies open-loop applications, as well as precision calibration and tolerance matching applications. Serial interface options include SPI (AD5270/AD5271) and I²C® (AD5272/AD5274).

These digipot ICs are available in thin 3 mm × 3 mm LFCSP (SON) and compact 10-lead MSOP packages. The parts are guaranteed to operate over the extended industrial temperature range of –40°C to +105°C.

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