Analog Devices, Inc. today introduced a 24-bit data acquisition system-on-chip (SoC) series designed to improve the performance of protection, monitoring, and power quality measurement equipment used to manage transmission and distribution (T&D) within smart grid systems. The AD7770 enables higher performance and smaller form factor protection relays, while the AD7771 enables power quality measurement equipment to provide early detection of power grid electrical faults. The third SoC in the series, the AD7779, ensures fast power-up in circuit breaker equipment.
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All three devices in the AD777x series claim the industry’s best combination of dynamic range and data throughput and feature eight simultaneous sampling channels that measure the output from current and voltage sensors in three-phase power applications. Each SoC channel achieves 112-dB of dynamic range at 8 kSPS, enabling the consolidation of protection and measurement functions on a single A/D converter channel. The AD777x series also includes an integrated sample rate converter, which simplifies the design challenge associated with making the power quality equipment compliant with the IEC61000-4-30 Class A standard.
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Additionally, the AD777x series lowers total system cost by eliminating the need for external components such as signal conditioning amplifiers and phase-locked loops (PLLs). The entire AD777x series incorporates sample rate converters that enable the fine adjustment of the sampling rate and maintain coherency to a 0.01Hz change in line frequency over a 50Hz (-15%) to 60Hz (+15%) range. This is a requirement for the IEC61000-4-30 Class A power quality standard.
The new devices also incorporate a number of on-chip diagnostic features that ease the design process for end-equipment safety integrity level (SIL) certification. An additional low-resolution SAR A/D converter channel operates from a separate power supply and provides data for system and chip diagnostics, improving confidence in data integrity and boosting overall system reliability.
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The AD7771’s high dynamic range, coupled with a high sampling rate, enables the reduction of the fast Fourier transform (FFT) noise floor. This enhances the detection of abnormal frequency spurs, which can signal a developing electrical fault, and enables early warning detection and preventative maintenance by power quality measurement equipment.
All three SoCs are packaged in 64-lead LFCSP and are sampling now, the AD7779 is scheduled for full production in January 2016 while the AD7770 and AD7771 are scheduled to enter production in May 2016. The AD7770 has an input bias of +/- 4 nA, an output data rate of 32kSPS, and a unit cost of $6.97 in lots of 1,000. The AD7771 has an input bias of +/- 4 nA, an output data rate of 128kSPS, and a unit cost of $7.94 in lots of 1,000. The AD7779 has an input bias of +/- 2nA, an output data rate of 16kSPS, and a unit cost of $5.90 in lots of 1,000.
source: http://www.powerpulse.net/story.php?storyID=33324
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