Data converter with internal reference delivers lowest power in its class

September 06, 2012 // By Nick Flaherty
Analog Devices has introduced the first product in a series of ultra-low-power, 12bit, 1MSPS SAR (successive approximation register) A/D converters with an internal 2.5V reference.

The AD7091R allows industrial and medical equipment designers to optimise operating and static power budgets and is designed for USB or battery powered data acquisition modules, handheld meters, field instruments, energy harvesting applications and devices such as portable electrocardiograms and heart rate monitors. The most power-efficient converter in its class, the device dissipates over 70 percent lower power than the closest SAR A/D converter competitor, in a package that is 33 percent smaller than competing 12-bit converters with internal reference.
“The AD7091R operates at over 3.5 times the power efficiency of competing A/D converters, and of discrete ADC and reference two-chip alternatives,” said Mike Britchfield, vice president, Industrial and Instrumentation Group, Analog Devices. “The significant power performance advantage was designed specifically for system engineers working within stringent system power constraints.”
The AD7091R core draws 349 μA typical at 3 V when operating at 1MSPS. The device’s power automatically scales with throughput. It draws 264-nA power down current and 21.6µA standby current, which allows designers to further optimise energy consumption for intermittent or one-shot conversions. The new device also achieves a 4.5 ppm/˚C reference temperature coefficient.
The EVAL-AD7091RSDZ evaluation board for the AD7091R is now available and priced at $59.00. The EVAL-SDP-CB1Z controller board must be ordered with the evaluation board and is priced at $99.00.
For ease of design in, IBIS models and software drivers are also now available. When coupled with low-power amplifiers, the AD7091R A/D converter is part of a chipset that reduces signal chain power dissipation. When used with the AD8031 op amp with rail-to-rail inputs and output, power is reduced by over 45 percent compared to previous offerings. For low-bandwidth applications, the AD8420 instrumentation amplifier used together with the AD7091R A/D converter provides a cost-sensitive solution that dissipates more than 60 percent lower power than previous solutions.
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