Texas Instruments ADS8381EVM, User Manual, Page: 13 / 30

Reference
2-3 Analog Interface
2.2 Reference
The ADS8381EVM provides an onboard 4.096-V reference circuit.
This reference voltage can be applied directly to the VREF pin of the
converter; it does not need to be buffered. The EVM also has provi-
sion for a user-supplied external reference voltage. This voltage can
be filtered, as needed, by routing the signal through amplifier U1.
The EVM allows users to select from two reference sources. Set
SJP1 and SJP2 to select onboard reference voltage (REF3040), or
a user-supplied reference voltage via P1 pin 20. See Table 2−2 for
jumper settings. See Chapter 6 for the full schematic.
Table 2−2. Solder Short Jumper Setting
Reference
Jumper Setting
Reference
Designator
Description
1−2 2−3
SJP1 Select REF3040 output for reference voltage Installed
†
Select buffered reference voltage Installed
SJP2 Select U3, REF3040, as 4.096-V reference Installed
†
Buffer the user−supplied reference voltage Installed
SJP3 Short (−)IN pin to ground Installed
†
N/A
SJP4 Apply offset voltage to A/D buffer Installed
†
N/A
SJP5 Set amplifier U1 negative supply to ground Installed
Set amplifier U1 negative supply to −V
CC
Installed†
SJP6 Set amplifier U2 negative supply to ground Installed
Set amplifier U2 negative supply to −V
CC
Installed
†
†
Factory-set condition