AD7927 datasheet(19/29 Pages) AD

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AD7927

Data Sheet

Rev. D | Page 18 of 28

VDRIVE

The AD7927 also has the VDRIVE feature. VDRIVE controls the volt-

age at which the serial interface operates. VDRIVE allows the ADC

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

if the AD7927 were operated with an AVDD of 5 V, the VDRIVE pin

could be powered from a 3 V supply. The AD7927 has a larger

dynamic range with an AVDD of 5 V while still being able to

interface to 3 V processors. Take care to ensure VDRIVE does not

exceed AVDD by more than 0.3 V (see the Absolute Maximum

Ratings section).

THE REFERENCE

An external reference source should be used to supply the

2.5 V reference to the AD7927. Errors in the reference source

result in gain errors in the AD7927 transfer function and add

to the specified full-scale errors of the part. A capacitor of at

least 0.1 μF should be placed on the REFIN pin. Suitable refer-

ence sources for the AD7927 include the AD780, REF192, and

the AD1582.

If 2.5 V is applied to the REFIN pin, the analog input range can

be either 0 V to 2.5 V or 0 V to 5 V, depending on the setting of

the RANGE bit in the control register.

AD7927 Datasheet(PDF) 19 Page - Analog Devices