Rainbow Electronics ADC10D020 - Manual (Page 24)

Applications Information
(Continued)
2.0 REFERENCE INPUTS
The V
RP
and V
RN
pins should each be bypassed with a 5 µF
(or larger) tantalum or electrolytic capacitor and a 0.1 µF
ceramic capacitor. Use these pins only for bypassing. DO
NOT connect anything else to these pins.
Figure 4 shows a simple reference biasing scheme with
minimal components. While this circuit will suffice for many
applications, the value of the reference voltage will depend
upon the supply voltage.
The circuit of Figure 5 is an improvement over the circuit of
Figure 4 because the reference voltage is independent of
supply voltage. This reduces problems of reference voltage
variability. The reference voltage at the V
REF
pin should be
bypassed to AGND with a 5 µF (or larger) tantalum or
electrolytic capacitor and a 0.1 µF ceramic capacitor.
The circuit of Figure 6 may be used if it is desired to obtain
a precise reference voltage not available with a fixed refer-
ence source. The 240
Ω
and 1k resistors can be replaced
with a potentiometer, if desired.
20025569
FIGURE 2. The ADC10D020 is designed for use with
differential signals of 1.0 V
P-P
with a common mode
voltage of 1.5V. The signal swing should not cause any
pin to experience a swing more than 300 mV beyond
the supply rails.
20025570
FIGURE 3. Use of an input transformer for
single-ended to differential conversion can simplify
circuit design for single-ended signals.
ADC10D020
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