Reference
2-3
Analog Interface
2.2
Reference
The ADS8383EVM provide an onboard 4.096-V reference circuit. The EVM
also has the provision for users to supply a reference voltage via connecter P1
pin 20. This reference voltage may be filtered by installing amplifier U1. The
converter itself has onboard reference buffer, therefore it is not necessary to
buffer externally. The reference buffer circuit on the EVM is not populated with
an amplifier. 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
Description
Jumper Setting
Reference
Designator
Description
1−2
2−3
SJP1
Select REF3040 output for reference voltage
Installed
†
Not installed
Select buffered reference voltage
Not installed
Installed
SJP2
Select U3, REF3040, as 4.096V reference
Installed
†
Buffer User supplied reference voltage
Not Installed
Installed
SJP3
Short (−)IN pin to ground
Installed
†
N/A
SJP4
Apply offset voltage to A/D buffer
Not Installed
N/A
SJP5
Set amplifier U1 negative supply to ground
Installed
SJP5
Set amplifier U1 negative supply to −V
CC
Not Installed
Installed
†
SJP6
Set amplifier U2 negative supply to ground
Installed
Not Installed
SJP6
Set amplifier U2 negative supply to −V
CC
Not Installed
Installed
†
† Factory set condition