Analog Devices, Inc. introduces its ADR29x family of low-noise, micropower, precision voltage references. The family's new XFET architecture provides better temperature coefficient linearity, lower noise, and lower thermal hysteresis than bandgap voltage references.

The ADR290, ADR291, ADR292 and ADR293 feature low supply voltage, low quiescent current, low noise, and excellent stability, making them particularly attractive for use in low-power applications, such as hand-held, battery-operated devices. Their high accuracy, low drift, and low-power consumption are key features for instrumentation, communications, and loop-current-powered transducers.

Analog Devices' ADR29x family provides output reference voltages of 2.048, 2.5, 4.096 and 5.0 Volts, for the ADR290/1/2/3, respectively. When operating at the same current as traditional bandgap references, these new XFET references produce only 6 ıV (peak-to-peak) of noise, compared with 24 ıV or more for bandgaps. Temperature drift for the E grade is a maximum of only 8 ppm/ıC, and long-term stability is 0.2 ppm per thousand hours at 25ıC. Lower cost grades F and G guarantee drift of 15 and 25 ppm/ıC, respectively. Initial reference voltage output is highly accurate with a maximum deviation of +/-2 mV, and quiescent current consumption is a maximum of 12 ıA.

These products didn't make the Product of the Week status, but it was a difficult decision. They are going to be a significant commercial success but the volume is not, I believe, going to get there real fast. Design engineers are extraordinarily reluctant to adopt new technologies in reference devices unless there was no previous option. The numbers from this family are good, however, and the basic 12 dB reduction in noise compared to equivalent bandgaps suggests to me that there are design problems out there just waiting for this solution. This is probably a part that you would seriously want to look at for your reference, unless you are in need of one at 1 V. Whether the technology is capable of lower references I have not yet investigated.

If you don't need the lower thermal drift of the E-graded devices you probably won't want to pay the price premium. The initial voltage deviation is extremely good although we seem to expect quiescents of 12 ıA and less these days for a non-processing part: it is odd how our frames of reference change so continually, and permanently. The first three devices in the family are available now, while the ADR293 will be available next month. Supply-voltage requirements range from 2.7 V for the ADR290, to 3.0 V for the ADR291, and 5 V for the ADR292. Pricing depends on package and thermal-drift rating and ranges from $1.95 to $6.06 in 1000 piece lots. The packages available are 8-pin SOIC, 8-pin TSSOP and 3-pin TO-92.