AD7294 datasheet(20/45 Pages) AD

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AD7294

Preliminary Technical Data

Rev. PrB | Page 20 of 45

is preferred. In addition, choosing a reference with an output

trim adjustment, such as the on-chip internal reference or the

AD431, allows a system designer to trim system errors by

setting a reference voltage to a voltage other than the nominal.

Long-term drift is a measure of how much the reference drifts

over time. A reference with a tight long-term drift specification

ensures that the overall solution remains stable during its entire

lifetime. If choosing an external reference, consider a tight tem-

perature coefficient specification to reduce the temperature

dependence of the system output voltage on ambient conditions.

ANALOG COMPARATOR LOOP

The AD7294 consists of two set-point comparators that are

used for independent analog control. The advantage of using

analog control for current sensing is the dynamic speed of the

analog loop vs. the speed of the digital loop, in that the analog

control loop does not have the digital delays inherent in ADC-

to-DAC signal processing. The ISENSEOVERRANGE pins signal

whether the instrumentation amplifiers voltage from the

current sense is greater then or less then the set point 240 mV.

The 240 mV is the fixed threshold voltage of the over-range

comparator and the current sense amplifier will saturate above

this.

AD7294 Datasheet(PDF) 20 Page - Analog Devices