Rainbow Electronics ADC10D020 - Manual (Page 26)

Applications Information
(Continued)
The V
CMO
output can be used as the ADC reference source
as long as care is taken to prevent excessive loading of this
pin. However, the V
CMO
output was not designed to be a
precision reference and has more variability than does a
precision reference. Refer to V
CMO
, Common Mode Voltage
Output, in the Electrical Characteristics table. Since the ref-
erence input of the ADC10D020 is buffered, there is virtually
no loading on the V
CMO
output by the V
REF
pin. While the
ADC10D020 will work with a 1.5V reference voltage, it is fully
specified for a 1.0V reference. To use the V
CMO
for a refer-
ence voltage at 1.0V, the 1.5V V
CMO
output needs to be
divided down. The divider resistor values need to be care-
fully chosen to prevent excessive V
CMO
loading. See Figure
7. While the average temperature coefficient of V
CMO
is 20
ppm/˚C, that temperature coefficient can be broken down to
a typical 50 ppm/˚C between −40˚C and +25˚C and a typical
−12 ppm/˚C between +25˚C and +85˚C.
20025572
FIGURE 5. Improved Low Component Count Reference Biasing
ADC10D020
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