Datasheet

AD7864
Rev. D | Page 12 of 28
nominal source impedance for this output. The tolerance on the
internal reference is ±10 mV at 25°C with a typical temperature
coefficient of 25 ppm/°C and a maximum error overtemperature
of ±20 mV.
If the application requires a reference with a tighter tolerance or
the AD7864 needs to be used with a system reference, the user
has the option of connecting an external reference to this V
REF
pin. The external reference effectively overdrives the internal
reference and thus provides the reference source for the ADC.
The reference input is buffered before being applied to the ADC
with the maximum input current of ±100 μA. Suitable reference
sources for the AD7864 include the AD680, AD780, REF192,
and REF43 precision 2.5 V references.