Datasheet

_
+
_
+
Vref
R
R
100E
100E
5E
5E
1nF
+IN
-IN
ADS8318
Vref/2
Bipolar
Analog
Input
±Vref
OPA Shownis THS4031orOPA211
ADS8318
www.ti.com SLAS568A –MAY 2008–REVISED MARCH 2011
Figure 58. Unipolar Differential Input Drive Configuration
Configuration for Bipolar Single-Ended Input
The following circuit shows a way to convert a single-ended bipolar input to the unipolar differential input needed
for for converter. Note that the higher values of the resistors at the input of the top OPA may reduce power
consumption of the circuit but increase noise in the driving circuit. One can choose these components based on
application needs.
Figure 59. Bipolar Single-Ended Input Drive Configuration
REFERENCE
The ADS8318 can operate with an external reference with a range from 2.048 V to V
DD
+ 0.1 V. A clean, low
noise, well-decoupled reference voltage on this pin is required to ensure good performance of the converter. A
low noise band-gap reference like the REF5050 can be used to drive this pin as shown in Figure 60 and
Figure 61. The capacitor should be placed as close as possible to the pins of the device.
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