Texas Instruments ADS8364EVM, Руководство пользователя, Страница: 15 / 28

2-5 Analog Interface
2.5 Reference Voltage
The ADS8364 has an internal 2.5-V reference source, which is accessed by
placing a shunt jumper on W13 pins 2 and 3 (factory default). If an external
reference is desired, the shunt jumper on W13 must be moved to cover pins 1
and 2. The ADS8364EVM provides two test-points, TP20 and TP22, as a
means to connect an external source. An external source should be applied
to TP20, referenced to TP22. The voltage input range on this node is 1.5 VDC
to 2.6 VDC. This voltage is buffered through the unity-gain noninverting buffer
and fed to the REFIN pin as well as the analog input circuitry.
Figure 2 - 3. ADS8364EVM Reference Circuit
_
+
_
+
5
6
U7B
OPA2350
OPA2350
3
2
7
1
4
8
C72
0.1
µ
F
C25
0.1
µ
F
C24
10
µ
F
+
TP19
AV
DD
U7A
C27
0.1
µ
F
W13
TP20
TP22
External
Reference
From REFOUT
To REFIN
V
ref
To Analog
Inputs