Datasheet

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NI
THS4031
(+)IN
(−)IN
W2
U5
C31
C17
C4
C18
R8
C38
R15
R16
C40
R11
NI
R7 49.9 
−V
CC
C3
0.1 F
4.7 F
−
+
0 
5 
6800 pF
C0G
4.7 F
0.1 F
+V
CC
1
0 
+V
IN
0 to
2REFin
4.1 Reference
Analog Interface
Table 1. Analog Input Connector (continued)
Description Signal Name Connector.Pin# Signal Name Description
Pin tied to ground AGND J1.11 J1.12 N/A Reserved
Reserved N/A J1.13 J1.14 N/A Reserved
Pin tied to ground AGND J1.15 J1.16 N/A Reserved
Pin tied to ground AGND J1.17 J1.18 N/A Reserved
Reserved N/A J1.19 J1.20 REF+ External reference input
The factory recommends that the analog input to any SAR-type converter be buffered and low-pass
filtered. The recommended circuit is shown in Figure 1 . This circuit was tested to ensure that the ac
specifications listed in the data sheet of the converter could be met, given a quality input signal.
Figure 1. ADS8322 Input Buffer Circuit
The ADS8322EVM can be configured to use its on-chip reference, or external reference voltage applied at
J1 pin 20 via W1. The EVM is shipped with the on-chip reference (REFout) shorted to REFin of the
converter.
Table 2. Jumper Setting
Reference Description Jumper Settings
Designator
1-2 2-3
W1 Short REFout (on-chip reference) to REFin pin Installed
(1)
Short user’s external reference to REFin pin Not installed
W2 Short R11 to U4 pin 2 Installed N/A
W3 Short R12 to U6 pin 2 Installed N/A
W4 Short U6 output to –IN Installed
Short REFout to –IN Installed
(1)
Factory-installed setting
ADS8322EVMSLAU086A – July 2002 – Revised December 2004 3