AD7294 datasheet(27/48 Pages) AD

27 / 48 page

AD7294

Data Sheet

Rev. I | Page 26 of 47

The AD7294 can also operate with an external reference.

Suitable reference sources for the AD7294 include the AD780,

AD1582, ADR431, REF193, and ADR391. In addition, choosing

a reference with an output trim adjustment, such as the ADR441,

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 low long-term drift specification

ensures that the overall solution remains stable during its entire

lifetime. If an external reference is used, select a low temperature

coefficient specification to reduce the temperature dependence

of the system output voltage on ambient conditions.

VDRIVE FEATURE

The AD7294 also has a VDRIVE feature to control the voltage at

which the I2C interface operates. The VDRIVE pin is connected to

the supply to which the I2C bus is pulled. This pin sets the input

and output threshold levels for the digital logic pins and the

ISENSE OVERRANGE pins. The VDRIVE feature allows the AD7294

to easily interface to both 3 V and 5 V processors. For example,

if the AD7294 is operated with a VDD of 5 V, the VDRIVE pin can

be powered from a 3 V supply, allowing a large dynamic range

with low voltage digital processors. Thus, the AD7294 can be

used with the 2 × VREF input range with a VDD of 5 V, yet remains

capable of interfacing to 3 V digital devices. Decouple this pin to

DGND with a 100 nF and a 1 μF capacitor.

AD7294 Datasheet(PDF) 27 Page - Analog Devices