Datasheet

AD5590
Rev. A | Page 29 of 44
Reference Section
An external reference source should be used to supply the 2.5 V
reference to the ADC. Errors in the reference source results in
gain errors in the ADC transfer function and adds to the specified
full-scale errors of the ADC. A capacitor of at least 0.1 µF should
be placed on the V
REFA
pin. Suitable reference sources for the
ADC include the AD780, REF193, and the AD1852.
If 2.5 V is applied to the V
REFA
pin, the analog input range can
either be 0 V to 2.5 V or 0 V to 5 V, depending on the range bit
in the control register.
AMPLIFIER SECTION
The operational amplifiers in the AD5590 are micropower,
rail-to-rail input and output amplifiers that feature low supply
current, low input voltage, and low current noise.
The parts are fully specified to operate from a single 5.0 V
supply, or ±2.5 V dual supplies. The ability to swing rail-to-rail
at both the input and output enables designers to buffer CMOS
ADCs, DACs, ASICs, and other wide output swing devices in
low power, single-supply systems. The amplifiers in the AD5590
are fully independent of the DAC and ADC sections. If some or
all of the amplifiers are not required, connect them as a
grounded unity-gain buffer, as shown in Figure 59.
07691-059
Figure 59. Configuration for Unused Amplifiers