Product category:
Analogue and Mixed Signal ICs
News Release from: Analog Devices | Subject: AD779x family
Edited by the Electronicstalk Editorial
Team on 10 June 2004
Convertors claim no compromise
A new family of sigma-delta analogue-to-digital convertors is claimed as an unprecedented low-noise and low-power solution for applications in industrial and medical instrumentation markets.
A new family of sigma-delta analogue-to-digital convertors (ADCs) is claimed as an unprecedented low-noise and low-power solution for applications in industrial and medical instrumentation markets Unlike traditional precision data-convertor solutions, which compromise on either power or noise, the new ADCs feature both low noise (40nV RMS) and low power (400uA), while offering a complete range of analogue functions in less board area
This article was originally published on Electronicstalk on 2 Jul 2008 at 8.00am (UK)
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This combination of features is ideal for applications where noise performance is critical, such as industrial process control and weigh scales, and space-constrained, low-power applications, such as portable instrumentation and medical equipment.
"Designers of instrumentation equipment are continually striving to find new ways to simplify their designs, while achieving the optimal balance of low noise and power", said Leo McHugh, Marketing Manager for Precision Convertors at Analog Devices.
"Our new data-convertor family solves these design challenges by delivering the best possible performance levels within a highly integrated, yet easy-to-use solution".
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The AD779x family of analogue-to-digital convertors, which include the AD7792 (16bit), AD7793 (24bit), AD7794 (24bit), AD7798 (16bit) and AD7799 (24bit), outperform comparable solutions - which trade low power for noise or vice versa - by delivering both low noise and low power.
Operating with a 2.7 to 5.25V power supply, these convertors consume only 400uA.
With noise of only 40nV RMS, they enable more accurate measurements in power-sensitive applications.
The output datarate from the devices is software programmable and can be varied from 4 to 500Hz.
At 16.6Hz they offer simultaneous rejection of 50 and 60Hz signals.
In addition to these performance advantages, the devices provide all the functionality required for instrumentation applications, reducing design work and eliminating many external components.
The AD779x data convertors include a high performance sigma-delta ADC, low-noise instrumentation programmable gain amplifier (PGA), multiplexer, current sources, clock, calibration registers, SPI interface, and a precision low-noise, low-drift reference (except the AD7798 and AD7799, which use an external reference for ratiometric measurements).
Designers have the flexibility to turn off the internal reference, and use an external reference instead.
The PGA, multiplexer, excitation current sources, and input bias voltages allow the AD779x family to connect directly to sensors in myriad applications including PLC/DCS analogue I/O measurement; temperature measurement using thermocouples, RTDs or thermistors; weigh scales; pressure and flow measurement; and general-purpose measurement equipment.
For pressure and weigh scale applications, a low-side power switch is available to power down the bridge between conversions, minimising system power consumption; the AD7799 features lower noise (30nV RMS) for these applications.
The AD7794 can accommodate six differential sensor channels, making it ideal for the higher channel requirements of industrial and factory PLC/DCS applications.
The other parts in the family can accommodate two or three differential channels.
The AD779x family of devices is sampling now and will be available in production quantities in November 2004.
The AD7792 (16bit), AD7793 (24bit), AD7798 (16bit) and AD7799 (24bit) are available in 16-lead TSSOPs (thin shrink small outline packages), with prices ranging from $3.80 to $5.10 per unit in 1000-piece quantities.
The AD7794 (24bit) is available in 24-lead TSSOPs, and priced at $5.80 per unit in 1000-piece quantities.
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