Texas Instruments ADS8364EVM, User Manual, Page: 12 / 28

2-2
2.1 Dual Supply—Input Buffer
The analog input to the ADS8364EVM board is comprised of six independent
OPA2132 operational amplifiers. The OPA2132s are powered from the
±
12-V
analog supply and connected as inverting amplifiers with a gain of 1. The
internal 2.5-V reference voltage is applied to the noninverting input of the
OPA2132s for level shifting.
Even though the ADS8364EVM board is configured at the factory for
±
12-V
analog operation, the EVM can tolerate maximum power supplies of
±
15 VDC.
However, care must be taken to ensure the
±
15 VDC limit is not exceeded or
potential damage to the op-amp circuits can occur.
Figure 2 - 1. ADS8364EVM Schematic—Analog Input Section
_
+
4
2
3
8
1
- V
IN
V
IN
U1A
TP9
R25
49.9
Ω
C56
A0+
R13
4.99 k
Ω
C1
330 pF
R1
4.99 k
Ω
W2
R2
4.99 k
Ω
V
ref
C7
*
R14
*
_
+
6
5
7
U1B
TP10
R26
49.9
Ω
C57
A0 -
R58
4.99 k
Ω
C32
330 pF
R45
4.99 k
Ω
W1
R56
4.99 k
Ω
C38
*
R59
*
V
ref
OPA2132
OPA2132
1
2
3
J1
A0
IN
C21
100 pF
1 nF
100 pF
Note: Components marked with an asterisk (*) are NOT INSTALLED.
This configuration allows single-ended signals of
±
2.5 V (5 V
pp
) to be applied
to either input of channels A, B, or C (JX pin 1 or 3 referenced to pin 2).
Differential signal inputs of
±
1.25 V (2.5 V
pp
) can be applied to the channel
input pairs (JX pin 1 and 3).